IM Board Review

A 75-year-old man with type 2 diabetes and hypothyroidism underwent bilateral total knee replacement at our hospital.

His functional capacity had been moderately limited by knee pain, but he could easily climb one flight of stairs without symptoms. His medications at that time included levothyroxine (Synthroid) and metformin (Glucophage). He had no known cardiac or pulmonary disease. The preoperative evaluation, including laboratory tests and electrocardiography, was within normal limits.

Spinal anesthesia was used for surgery, and he was given 2 mg of midazolam (Versed) intravenously for sedation. No additional sedation was given. He was given oxygen via nasal cannula at 2 L/min.

All vital signs were stable at the start of the procedure. However, about halfway through, when the thigh tourniquet was released, his oxygen saturation dropped abruptly from 100% to 92%. All other vital signs remained stable, and he was asymptomatic, was oriented to person, time, and place, was conversing freely, and was in no distress. The oxygen flow was increased to 6 L/min, his oxygen saturation improved, and the procedure was then completed as planned.

At the conclusion of the surgery, before the patient was transported to the postanesthesia care unit (PACU) and while his oxygen flow rate was still 6 L/min, his oxygen saturation again dropped to 92%. A simple face mask was placed, and the oxygen flow rate was increased to 10 L/min. His oxygen saturation stayed low, near 90%.

Bleeding during surgery had been nominal. He had received 2 L of lactated Ringer’s solution and 500 mL of hetastarch (Hextend) during surgery. He continued to be asymptomatic in the PACU.

1. What is the most likely cause of oxygen desaturation during bilateral total knee arthroplasty?

• Fat embolism
• Intraoperative pneumonia
• Venous thromboembolism with pulmonary embolism
• Acute myocardial infarction
• Acute pulmonary edema
• Excessive sedation

The differential diagnosis of oxygen desaturation during orthopedic procedures is listed in Table 1.

Fat embolism is the most likely cause, particularly given the greater fatty embolic load that occurs with bilateral total knee arthroplasty than with unilateral total knee arthroplasty.

At what point the maximal showering of fat emboli occurs is not known. Fat may be released into the circulation with pressurization of the medullary canal during surgery or with manipulation of a fracture. The emboli may collect in the leg veins and then be released in a shower when the thigh tourniquet is released. Vasoactive mediators and methylmethacrylate cement released into the circulatory system after tourniquet deflation may also cause vasodilation, hypotension, and increased dead-space ventilation, resulting in hypoxia and a drop in end-tidal CO₂.

Pneumonia during surgery is rare without an apparent aspiration event.

Venous thromboembolism is possible but is more likely later in the postoperative period after major orthopedic surgery.

Acute myocardial infarction could present with hypoxia, particularly in a diabetic patient, who may not experience chest pain. However, intraoperative electrocardiographic changes would likely be seen. If myocardial infarction is suspected, postoperative serial electrocardiograms and measuring troponin and cardiac enzyme levels aid in the diagnosis.

Acute pulmonary edema is possible but not as highly suspected, as the patient had no history of congestive heart failure and received an appropriate amount of fluid for this type of surgery.

Excessive sedation could cause hypoventilation and, thus, oxygen desaturatation. However, this patient’s oxygen desaturatation began more than an hour after the midazolam was given. Midazolam is a short-acting benzodiazepine. It is unlikely that the patient would show signs of hypoventilation and oversedation an hour after the drug was given. Our patient also did not show any signs of excessive sedation, as he was awake and conversing during the surgery.

Fat emboli vs fat embolism syndrome

Fat embolism is the presence of fat drops within the systemic and pulmonary microcirculation, with or without clinical sequelae.¹ Fat embolism syndrome, on the other hand, is defined as injury to and dysfunction of one or more organs as a result of the embolization of fat, usually within 24 hours of injury or orthopedic surgery.²

Fat embolism syndrome is an unpredictable condition with a varied presentation. Fat droplets are thought to embolize via the venous circulation into the pulmonary arteries, occluding small blood vessels in the lung. However, they also get into the arterial circulation and occlude arteries in the brain, kidney, heart, and liver (more on this phenomenon below).

Fat embolism is reported to originate primarily from fractures of the femur, tibia, and pelvis.^2,3 As many as 90% of trauma patients have been shown to have evidence of fat embolism on autopsy.⁴ However, only a small number of patients develop the classic fat embolism syndrome,^2,3,5 Why some develop the syndrome and others do not is still unknown.

Orthopedic procedures associated with fat embolization include knee arthroplasty and hip arthroplasty, particularly if it involves intramedullary manipulation or medullary fixation.⁶ It has also been reported during spinal procedures in which pedicular screws are used.⁷ The syndrome occurs in 0.25% to 30% of patients following multiple fractures and in 0.1% to 12% of patients during or following knee or hip arthroplasty.

One study⁸ showed evidence of fat on transesophageal echocardiography in 88% of patients undergoing medullary reaming of lower-extremity fractures and hip hemiarthroplasty. Blood sampling from the right atrium confirmed that fat was responsible for the echocardiographic abnormalities. The study also showed that the severity of the embolic showering correlated with the severity of hypoxia and the decrease in end-tidal CO₂.⁸

 

CASE CONTINUED

On arrival at the PACU, our patient’s oxygen saturation was 94% while he was breathing oxygen via a simple face mask at a flow rate of 10 L/min. His heart rate was 60 bpm, blood pressure 110/60 mm Hg, and temperature 37.5°C (96.3°F). Chest sounds were normal on auscultation.

However, 3 hours later, his mental status rapidly deteriorated. He was oriented only to person, and he was drowsy. He had escalating respiratory distress with a rapid respiratory rate and decreasing oxygen saturation. At this point, auscultation of his chest wall revealed bilateral crackles and rales.

He was promptly intubated. Profuse fluid and secretions were noted to be coming from his lungs, filling the endotracheal tube. Arterial blood gas measurement showed a pH of 7.22, Pao₂ 64 mm Hg, and Paco₂ 56 mm Hg on 100% fraction of inspired oxygen, with no increased anion gap.

2. Which consequence of fat embolism is most likely at this time in this patient?

• Coexisting sepsis
• Fat embolism syndrome
• Acute cardioembolic stroke
• Anaphylaxis

Fat embolism syndrome should be highly suspected in this patient. As mentioned, it can affect many different organs. It is the most serious condition resulting from fat embolization after surgery or trauma.

Sepsis was unlikely in our patient, since he presented for his surgery in good health and with no preexisting signs or symptoms of infection. Acute cardioembolic stroke could have caused the neurologic signs, but this would not necessarily explain the coexisting hypoxia. An anaphylactic reaction to drugs or surgical cement would most likely present intraoperatively, shortly after exposure occurred, rather than several hours after surgery.

How common is fat embolism syndrome?

The occurrence rate of fat embolism syndrome has been reported to be 0.25% to 30% after multiple fractures and 0.1% to 12% after knee and hip joint surgery, with a mortality rate of 13% to 36%.^2,9–14 The rate of occurrence after unilateral total knee joint replacement has been reported to be 1.8% to 5%, and 4% to 12% after bilateral total knee replacement.^15–19

The syndrome is relatively more common with traumatic fractures of the lower extremities. However, it has also been reported with liposuction, total parenteral nutrition, bone marrow harvest and transplantation, burns, and acute pancreatitis, to mention a few.¹⁰

The broad range of reported incidence rates can be attributed to the fact that many studies were in patients with multiple trauma, whose concomitant injuries may have made it difficult to clearly define the contribution of fat embolism syndrome to the overall rates of morbidity and mortality. Also, different studies used different criteria to define the syndrome.

How does fat embolism syndrome occur?

Two hypotheses for how this syndrome occurs were proposed nearly a century ago.^20,21

The “mechanical” theory is that fat emboli are formed as a result of trauma and disruption of adipose tissue and other cells in the bone marrow. Increases in intramedullary pressure force the fat emboli through damaged medullary venous channels in the bone and into the circulation of the lower extremities. This embolization of fat causes an initial mechanical pulmonary obstruction. Mechanical obstruction by fat emboli in the pulmonary system leads to increased pulmonary pressures and an increase in right heart outflow pressure. The right heart becomes strained, leading to a decreased right-sided cardiac output. As a result, the left heart filling pressures diminish and hypotension ensues.²⁰

The “biochemical” theory, on the other hand, is that chylomicrons within the vascular system are modified and their stability is compromised as a result of stress. These traumatized chylomicrons then coalesce to form droplets of fat that accumulate in the pulmonary circulation and produce a mechanical obstruction. This would explain why nontraumatic, nonorthopedic insults can produce this syndrome.

Autopsy studies show that there is little correlation between the presence and quantity of intravascular fat and the severity of clinical symptoms, thus implying that the syndrome is caused by more than just mechanical obstruction. The biochemical theory postulates that fat globules within the circulatory system then cause the release of lipase from the pulmonary alveolar cells, which then hydrolyses the fat into free fatty acids. These free fatty acids cause an inflammatory reaction, complementmediated leukocyte aggregation, chemotoxin release, and subsequently endothelial damage. These vasoactive substances damage type 2 pneumocytes and lead to an increased permeability of the pulmonary capillary beds. Acute respiratory distress syndrome (ARDS) may ensue. Disseminated intravascular coagulation may occur as a result of the formation of microthrombi involving lipids, platelets, and fibrin.^21,22

Embolization of fat to the central nervous system can occur as fat globules cross into the systemic circulation via a patent foramen ovale, an atrioventricular shunt, or the pulmonary capillaries. This can then result in cerebral ischemia.²³

Although patent foramen ovale may seem the most direct route for cerebral embolization, the neurologic impairment and signs of cerebral emboli in fat embolism syndrome may occur in the absence of patent foramen ovale.^24,25 The fat globules may actually go through the lung capillaries, being flexible and forced through by increased pulmonary pressure.

But whether the cause of fat embolism syndrome is occlusion by globules, the release of biochemical mediators, or a combination of both is unknown. Both mechanisms are likely responsible. We can only suspect that the degree of fat load and intrinsic metabolic differences between individuals account for the variation in susceptibility.

 

FAT EMBOLI AFFECT THE LUNGS, SKIN, AND BRAIN

3. Where on the body is the rash associated with fat embolism syndrome usually seen?

• Face
• Near a site of fracture or surgery
• Chest, axilla, conjunctiva
• Distal extremities

Petechiae are part of the classic presenting triad of fat embolism syndrome, which also includes pulmonary and cerebral dysfunction.

Petechiae usually appear on the 2nd to 4th day after injury.²⁶ They are usually found across the chest, the anterior axillary folds, and the neck, as well as on the oral mucosa and the conjunctiva. The rash is caused by occlusion of dermal capillaries by fat, which increases their fragility.¹⁰

Pulmonary changes usually begin with tachypnea, dyspnea, and a drop in oxygen saturation, leading to generalized hypoxia. Respiratory symptoms are present in 100% of cases.² Respiratory symptoms can acutely develop with the sudden manipulation of a fracture, reaming of bone, or release of a limb tourniquet.²⁷

Cerebral dysfunction can be variable, from anxiety and confusion to seizures and coma. The neurologic signs are typically diffuse; however, focal symptoms such as hemiplegia or aphasia can occasionally occur. Neurologic signs are present in 80% of cases.^2,28

Body systems affected by fat embolism syndrome are summarized in Table 2.

4. How many hours after injury does fat embolism syndrome typically manifest?

• 1 to 2 hours
• 6 to 12 hours
• 12 to 20 hours
• 24 to 48 hours
• 72 to 84 hours

Most patients develop signs and symptoms 24 to 48 hours after injury. Patients presenting earlier than 12 hours usually have a more fulminant course.²⁹

The time between fat embolization and the development of fat embolism syndrome is thought to be related to the time required for the metabolic conversion of fat to free fatty acids.³⁰ We suspect that the early desaturation seen in our patient was the result of a heavy showering of fat intraoperatively. However, this could only be concluded after we had ruled out other causes of acute hypoxia and hypotension.

Fat embolism syndrome is a diagnosis of exclusion and is based on clinical criteria. No specific sign, symptom, or test is pathognomonic. It may often be confused with other conditions such as systemic inflammatory response syndrome or sepsis. However, the triad of respiratory and neurologic symptoms and petechiae coupled with the clinical picture of recent trauma or orthopedic surgery almost assures the diagnosis.

Fat embolism syndrome can range from subclinical to fulminating, with the more fulminating course attributable to a huge load of fat emboli, which leads to acute cor pulmonale.

The diagnostic criteria established by Gurd and Wilson¹³ are widely accepted and include major, minor, and laboratory criteria (Table 3). According to their criteria, the diagnosis of fat embolism syndrome requires the presence of one major feature plus four minor features plus fat macroglobulinemia. Major signs appear in 60% of patients within 24 hours and in 85% of patients within 48 hours.¹³

Variations on these diagnostic guidelines require two major criteria, one major and three minor criteria, two major and two minor criteria, and one major and two minor criteria.³¹ Other authors, perceiving these criteria to be insensitive, have focused on other factors, including hypoxemia by arterial blood gas monitoring.^12,32 Lindeque at al¹² thus included arterial blood gas analysis in their criteria (Table 4). However, their criteria have been criticized for focusing only on the pulmonary system, and many of these features may be present in patients with ARDS with a cause other than fat embolization, such as burns, septicemia, aspiration, and multiple transfusions.

Schonfeld et al³² created a fat embolism index to diagnose fat embolism syndrome; a score greater than 5 indicates that the syndrome is likely (Table 5).³²

Regardless of the criteria used, one must have a high index of suspicion for fat embolization syndrome in patients undergoing orthopedic procedures, particularly hip and knee surgery, and in patients with fractures, especially fractures of the femur, tibia, or pelvis and multiple, concomitant fractures.

CASE CONTINUED

Our patient was given furosemide (Lasix) empirically for diuresis and to improve oxygenation. However, his oxygen saturation remained low.

Chest radiography 4 hours after surgery showed bilateral pulmonary infiltrates. Serial electrocardiography showed no acute changes. Levels of cardiac enzymes and troponins were normal. Transthoracic echocardiography showed no left ventricular dysfunction, a normal right ventricle, and no evidence of valvular lesions. Urine and blood fat stains were negative, but the sputum stain was positive for copious extracellular fat. The patient became comatose 5 hours postoperatively. Computed tomography of the brain was normal. He was transferred to the surgical intensive care unit.

The clinical course was marked by hemodynamic instability requiring norepinephrine (Levophed) and vasopressin (Pitressin) for hypotension. Right ventricular filling pressures via central venous pressure monitoring showed no evidence of hypovolemia. The hemoglobin concentration and the hematocrit were stable, with no evidence of acute or ongoing bleeding. Blood, urine, and sputum cultures remained negative. Acute myocardial infarction was ruled out by serial electrocardiography, cardiac enzyme testing, and troponin testing.

Magnetic resonance imaging (MRI) of the brain on postoperative day 2 showed foci of acute ischemia suggestive of embolic phenomena consistent with fat embolism syndrome (Figure  1). Transthoracic echocardiography was repeated but again showed no evidence of a patent foramen ovale. Electroencephalography on postoperative day 4 showed severe, diffuse encephalopathy. There was no petechial skin rash. Other laboratory studies showed progressive thrombocytopenia with a platelet count of 53 × 199/L on postoperative day 3.

 

TESTS THAT AID THE CLINICAL DIAGNOSIS

Although no single laboratory test is pathognomonic for fat embolism syndrome, several tests may help raise suspicion of it, especially in the setting of fracture or an orthopedic surgical procedure.

Arterial blood gases must be measured. A Pao₂ of less than 60 mm Hg with no other obvious lung pathology in an orthopedic surgery patient is highly suspicious.¹² An alveolar-arterial gradient of greater than 100 mm Hg may further increase suspicion.

Tests for fat. The blood and urine may be examined for fat, although positive findings are not specific for fat embolism syndrome.³³ Fat in the urine indicates the occurrence of massive fat embolism, but this is not always accompanied by the syndrome.³⁴ Gurd and Wilson¹³ found fat globules larger than 8 μm circulating in the serum in all documented cases. They stated that, even though the relationship of large fat globules to the pathogenesis of the clinical picture remains obscure, the demonstration of their presence can be helpful in the diagnosis.¹³

Also, samples obtained with bronchoalveolar lavage may be examined for fat. The macrophages may be stained for fat using the oil red O stain. Again, this is a nonspecific marker, as fat-stained macrophages are seen in trauma patients,³⁵ but the finding has a very high negative predictive value.³⁶ Anemia, thrombocytopenia, hypofibrinogenemia, an elevated lipase level, and a high erythrocyte sedimentation rate may be found in fat embolism syndrome.¹³

Chest radiography may show bilateral infiltrates, as in ARDS, but this is not diagnostic for fat embolism syndrome.

Electrocardiography may show changes in ST and T waves and signs of right heart strain.

Transesophageal echocardiography may show increased right heart and pulmonary artery pressures.

Computed tomography is often negative,^37,38 but T2-weighted MRI is useful in the diagnosis of cerebral fat embolism syndrome, as it can show intracerebral microinfarcts as early as 4 hours after the onset of neurologic symptoms, and these findings correlate well with the clinical severity of brain injury.

Diffusion-weighted MRI may enhance the sensitivity and specificity of the neuroradiologic diagnosis. Diffusion-weighted MRI typically shows multiple nonconfluent areas of high-intensity signals or bright spots on a dark background, known as a “starfield pattern.” This pattern has been suggested to be pathognomonic of acute cerebral microinfarction. The abnormalities presumably reflect foci of cytotoxic edema that develops immediately, unlike vasogenic edema, seen in T2-weighted images, which may take up to several days to develop. Although these images are not necessarily specific for fat emboli, they are useful in helping make the diagnosis. Thus, diffusionweighted MRI should be done if fat embolism syndrome is suspected.^38,39

CASE CONCLUDED

The patient’s course in the intensive care unit was further complicated by gastrointestinal bleeding and renal failure. His neurologic status did not improve. Repeated MRI of the brain showed evolving bilateral watershed infarction throughout the cortices. The neurologic consult service diagnosed the patient as having severe encephalopathy with a very poor prognosis. The decision was made to withdraw care. He was placed under palliative care and died on postoperative day 22.

DRUG TREATMENT OF FAT EMBOLISM SYNDROME

5. Which of the following drugs has been proven to be effective in treating fat embolism syndrome?

• Intravenous ethanol
• Steroids
• Heparin
• Dextran
• Aspirin
• None of the above

None of the above has been proven to be effective in treating this disorder. The management is largely supportive. Thus, prevention, early diagnosis, and symptom management are vital.

Pulmonary and hemodynamic support are the cornerstones of successful treatment. Aggressive respiratory support is often needed. Management of acute lung injury and ARDS focuses on achieving acceptable gas exchange while preventing ventilator-associated lung injury. Intravascular volume must be supported. Inotropes and pulmonary vasodilators may be required to maintain hemodynamics. Exacerbation of central nervous system ischemia from hypotension or hypoxia should be avoided.

If the thrombocytopenia leads to clinical bleeding, platelet transfusions may be warranted.

Supportive care should include prophylaxis of deep venous thrombosis and of gastrointestinal bleeding, and maintenance of nutrition.⁴⁰ Patients who receive supportive care generally have a favorable outcome, with a mortality rate of less than 10%.²⁸

Drug studies have been inconclusive

Drugs suggested in the treatment of fat embolism syndrome include heparin, aspirin, dextran, hypertonic glucose, and alcohol, but the results have been inconclusive.^{3,11,23,40–43}

Heparin stimulates lipase activity, consequently decreasing the concentration of circulating fat globules. However, the increase in levels of free fatty acids may actually worsen the clinical picture. For this reason, and because of anticoagulation concerns and evidence of increased mortality rates, heparin is now contraindicated in the treatment of fat embolism syndrome.^2,41,43

Alcohol. Patients with a higher blood alcohol level at the time of injury have been reported to have a lower incidence of fat embolism syndrome. Alcohol inhibits lipase, suppressing the rise of free fatty acids. In experimental studies, the incidence of fat embolism syndrome was lower when the blood alcohol level was maintained at 20 mg/dL. However, no prospective randomized trial has been done to determine the clinical efficacy of ethanol as a treatment for this condition.^5,42

Dextran has been advocated, owing to its ability to improve small-vessel perfusion, but bleeding risk and acute renal failure associated with this drug have limited its use.⁵

N-acetylcysteine has been shown to attenuate fat-induced lung injury in a study of rats with induced fat embolism syndrome.⁴⁴

Corticosteroid treatment for this condition is controversial. Studies in patients with femoral and tibial fractures show that steroids reduce the incidence of fat embolism syndrome when given prophylactically, and those treated with steroids had a higher Pao₂ than controls. Doses of methylprednisolone in these studies ranged between 9 mg/kg to 90 mg/kg. A drawback of these studies is their small number of patients.^12,32,45,46

A meta-analysis⁴⁷ of randomized trials of corticosteroids to prevent fat embolism syndrome in patients with long-bone fractures identified 104 such studies. Only 7 of the 104 were considered adequate. In 389 patients with long-bone fractures, prophylactic corticosteroids reduced the risk of fat embolism syndrome by 78% (95% confidence interval 43%–92%) and corticosteroids also significantly reduced the risk of hypoxia with no difference in rates of infection or death. However, the overall quality of the trials was poor, and the authors of the meta-analysis concluded that more study is needed before corticosteroids could be formally recommended.⁴⁷

There is no evidence that steroids improve the overall clinical course of already established fat embolism syndrome.^12,32,45 The dosing and optimal timing of administration have also not been established. High doses pose a risk of septic complications, which may be devastating for the posttrauma or postoperative patient.

A 75-year-old man with type 2 diabetes and hypothyroidism underwent bilateral total knee replacement at our hospital.

His functional capacity had been moderately limited by knee pain, but he could easily climb one flight of stairs without symptoms. His medications at that time included levothyroxine (Synthroid) and metformin (Glucophage). He had no known cardiac or pulmonary disease. The preoperative evaluation, including laboratory tests and electrocardiography, was within normal limits.

Spinal anesthesia was used for surgery, and he was given 2 mg of midazolam (Versed) intravenously for sedation. No additional sedation was given. He was given oxygen via nasal cannula at 2 L/min.

All vital signs were stable at the start of the procedure. However, about halfway through, when the thigh tourniquet was released, his oxygen saturation dropped abruptly from 100% to 92%. All other vital signs remained stable, and he was asymptomatic, was oriented to person, time, and place, was conversing freely, and was in no distress. The oxygen flow was increased to 6 L/min, his oxygen saturation improved, and the procedure was then completed as planned.

At the conclusion of the surgery, before the patient was transported to the postanesthesia care unit (PACU) and while his oxygen flow rate was still 6 L/min, his oxygen saturation again dropped to 92%. A simple face mask was placed, and the oxygen flow rate was increased to 10 L/min. His oxygen saturation stayed low, near 90%.

Bleeding during surgery had been nominal. He had received 2 L of lactated Ringer’s solution and 500 mL of hetastarch (Hextend) during surgery. He continued to be asymptomatic in the PACU.

1. What is the most likely cause of oxygen desaturation during bilateral total knee arthroplasty?

• Fat embolism
• Intraoperative pneumonia
• Venous thromboembolism with pulmonary embolism
• Acute myocardial infarction
• Acute pulmonary edema
• Excessive sedation

The differential diagnosis of oxygen desaturation during orthopedic procedures is listed in Table 1.

Fat embolism is the most likely cause, particularly given the greater fatty embolic load that occurs with bilateral total knee arthroplasty than with unilateral total knee arthroplasty.

At what point the maximal showering of fat emboli occurs is not known. Fat may be released into the circulation with pressurization of the medullary canal during surgery or with manipulation of a fracture. The emboli may collect in the leg veins and then be released in a shower when the thigh tourniquet is released. Vasoactive mediators and methylmethacrylate cement released into the circulatory system after tourniquet deflation may also cause vasodilation, hypotension, and increased dead-space ventilation, resulting in hypoxia and a drop in end-tidal CO₂.

Pneumonia during surgery is rare without an apparent aspiration event.

Venous thromboembolism is possible but is more likely later in the postoperative period after major orthopedic surgery.

Acute myocardial infarction could present with hypoxia, particularly in a diabetic patient, who may not experience chest pain. However, intraoperative electrocardiographic changes would likely be seen. If myocardial infarction is suspected, postoperative serial electrocardiograms and measuring troponin and cardiac enzyme levels aid in the diagnosis.

Acute pulmonary edema is possible but not as highly suspected, as the patient had no history of congestive heart failure and received an appropriate amount of fluid for this type of surgery.

Excessive sedation could cause hypoventilation and, thus, oxygen desaturatation. However, this patient’s oxygen desaturatation began more than an hour after the midazolam was given. Midazolam is a short-acting benzodiazepine. It is unlikely that the patient would show signs of hypoventilation and oversedation an hour after the drug was given. Our patient also did not show any signs of excessive sedation, as he was awake and conversing during the surgery.

Fat emboli vs fat embolism syndrome

Fat embolism is the presence of fat drops within the systemic and pulmonary microcirculation, with or without clinical sequelae.¹ Fat embolism syndrome, on the other hand, is defined as injury to and dysfunction of one or more organs as a result of the embolization of fat, usually within 24 hours of injury or orthopedic surgery.²

Fat embolism syndrome is an unpredictable condition with a varied presentation. Fat droplets are thought to embolize via the venous circulation into the pulmonary arteries, occluding small blood vessels in the lung. However, they also get into the arterial circulation and occlude arteries in the brain, kidney, heart, and liver (more on this phenomenon below).

Fat embolism is reported to originate primarily from fractures of the femur, tibia, and pelvis.^2,3 As many as 90% of trauma patients have been shown to have evidence of fat embolism on autopsy.⁴ However, only a small number of patients develop the classic fat embolism syndrome,^2,3,5 Why some develop the syndrome and others do not is still unknown.

Orthopedic procedures associated with fat embolization include knee arthroplasty and hip arthroplasty, particularly if it involves intramedullary manipulation or medullary fixation.⁶ It has also been reported during spinal procedures in which pedicular screws are used.⁷ The syndrome occurs in 0.25% to 30% of patients following multiple fractures and in 0.1% to 12% of patients during or following knee or hip arthroplasty.

One study⁸ showed evidence of fat on transesophageal echocardiography in 88% of patients undergoing medullary reaming of lower-extremity fractures and hip hemiarthroplasty. Blood sampling from the right atrium confirmed that fat was responsible for the echocardiographic abnormalities. The study also showed that the severity of the embolic showering correlated with the severity of hypoxia and the decrease in end-tidal CO₂.⁸

 

CASE CONTINUED

On arrival at the PACU, our patient’s oxygen saturation was 94% while he was breathing oxygen via a simple face mask at a flow rate of 10 L/min. His heart rate was 60 bpm, blood pressure 110/60 mm Hg, and temperature 37.5°C (96.3°F). Chest sounds were normal on auscultation.

However, 3 hours later, his mental status rapidly deteriorated. He was oriented only to person, and he was drowsy. He had escalating respiratory distress with a rapid respiratory rate and decreasing oxygen saturation. At this point, auscultation of his chest wall revealed bilateral crackles and rales.

He was promptly intubated. Profuse fluid and secretions were noted to be coming from his lungs, filling the endotracheal tube. Arterial blood gas measurement showed a pH of 7.22, Pao₂ 64 mm Hg, and Paco₂ 56 mm Hg on 100% fraction of inspired oxygen, with no increased anion gap.

2. Which consequence of fat embolism is most likely at this time in this patient?

• Coexisting sepsis
• Fat embolism syndrome
• Acute cardioembolic stroke
• Anaphylaxis

Fat embolism syndrome should be highly suspected in this patient. As mentioned, it can affect many different organs. It is the most serious condition resulting from fat embolization after surgery or trauma.

Sepsis was unlikely in our patient, since he presented for his surgery in good health and with no preexisting signs or symptoms of infection. Acute cardioembolic stroke could have caused the neurologic signs, but this would not necessarily explain the coexisting hypoxia. An anaphylactic reaction to drugs or surgical cement would most likely present intraoperatively, shortly after exposure occurred, rather than several hours after surgery.

How common is fat embolism syndrome?

The occurrence rate of fat embolism syndrome has been reported to be 0.25% to 30% after multiple fractures and 0.1% to 12% after knee and hip joint surgery, with a mortality rate of 13% to 36%.^2,9–14 The rate of occurrence after unilateral total knee joint replacement has been reported to be 1.8% to 5%, and 4% to 12% after bilateral total knee replacement.^15–19

The syndrome is relatively more common with traumatic fractures of the lower extremities. However, it has also been reported with liposuction, total parenteral nutrition, bone marrow harvest and transplantation, burns, and acute pancreatitis, to mention a few.¹⁰

The broad range of reported incidence rates can be attributed to the fact that many studies were in patients with multiple trauma, whose concomitant injuries may have made it difficult to clearly define the contribution of fat embolism syndrome to the overall rates of morbidity and mortality. Also, different studies used different criteria to define the syndrome.

How does fat embolism syndrome occur?

Two hypotheses for how this syndrome occurs were proposed nearly a century ago.^20,21

The “mechanical” theory is that fat emboli are formed as a result of trauma and disruption of adipose tissue and other cells in the bone marrow. Increases in intramedullary pressure force the fat emboli through damaged medullary venous channels in the bone and into the circulation of the lower extremities. This embolization of fat causes an initial mechanical pulmonary obstruction. Mechanical obstruction by fat emboli in the pulmonary system leads to increased pulmonary pressures and an increase in right heart outflow pressure. The right heart becomes strained, leading to a decreased right-sided cardiac output. As a result, the left heart filling pressures diminish and hypotension ensues.²⁰

The “biochemical” theory, on the other hand, is that chylomicrons within the vascular system are modified and their stability is compromised as a result of stress. These traumatized chylomicrons then coalesce to form droplets of fat that accumulate in the pulmonary circulation and produce a mechanical obstruction. This would explain why nontraumatic, nonorthopedic insults can produce this syndrome.

Autopsy studies show that there is little correlation between the presence and quantity of intravascular fat and the severity of clinical symptoms, thus implying that the syndrome is caused by more than just mechanical obstruction. The biochemical theory postulates that fat globules within the circulatory system then cause the release of lipase from the pulmonary alveolar cells, which then hydrolyses the fat into free fatty acids. These free fatty acids cause an inflammatory reaction, complementmediated leukocyte aggregation, chemotoxin release, and subsequently endothelial damage. These vasoactive substances damage type 2 pneumocytes and lead to an increased permeability of the pulmonary capillary beds. Acute respiratory distress syndrome (ARDS) may ensue. Disseminated intravascular coagulation may occur as a result of the formation of microthrombi involving lipids, platelets, and fibrin.^21,22

Embolization of fat to the central nervous system can occur as fat globules cross into the systemic circulation via a patent foramen ovale, an atrioventricular shunt, or the pulmonary capillaries. This can then result in cerebral ischemia.²³

Although patent foramen ovale may seem the most direct route for cerebral embolization, the neurologic impairment and signs of cerebral emboli in fat embolism syndrome may occur in the absence of patent foramen ovale.^24,25 The fat globules may actually go through the lung capillaries, being flexible and forced through by increased pulmonary pressure.

But whether the cause of fat embolism syndrome is occlusion by globules, the release of biochemical mediators, or a combination of both is unknown. Both mechanisms are likely responsible. We can only suspect that the degree of fat load and intrinsic metabolic differences between individuals account for the variation in susceptibility.

 

FAT EMBOLI AFFECT THE LUNGS, SKIN, AND BRAIN

3. Where on the body is the rash associated with fat embolism syndrome usually seen?

• Face
• Near a site of fracture or surgery
• Chest, axilla, conjunctiva
• Distal extremities

Petechiae are part of the classic presenting triad of fat embolism syndrome, which also includes pulmonary and cerebral dysfunction.

Petechiae usually appear on the 2nd to 4th day after injury.²⁶ They are usually found across the chest, the anterior axillary folds, and the neck, as well as on the oral mucosa and the conjunctiva. The rash is caused by occlusion of dermal capillaries by fat, which increases their fragility.¹⁰

Pulmonary changes usually begin with tachypnea, dyspnea, and a drop in oxygen saturation, leading to generalized hypoxia. Respiratory symptoms are present in 100% of cases.² Respiratory symptoms can acutely develop with the sudden manipulation of a fracture, reaming of bone, or release of a limb tourniquet.²⁷

Cerebral dysfunction can be variable, from anxiety and confusion to seizures and coma. The neurologic signs are typically diffuse; however, focal symptoms such as hemiplegia or aphasia can occasionally occur. Neurologic signs are present in 80% of cases.^2,28

Body systems affected by fat embolism syndrome are summarized in Table 2.

4. How many hours after injury does fat embolism syndrome typically manifest?

• 1 to 2 hours
• 6 to 12 hours
• 12 to 20 hours
• 24 to 48 hours
• 72 to 84 hours

Most patients develop signs and symptoms 24 to 48 hours after injury. Patients presenting earlier than 12 hours usually have a more fulminant course.²⁹

The time between fat embolization and the development of fat embolism syndrome is thought to be related to the time required for the metabolic conversion of fat to free fatty acids.³⁰ We suspect that the early desaturation seen in our patient was the result of a heavy showering of fat intraoperatively. However, this could only be concluded after we had ruled out other causes of acute hypoxia and hypotension.

Fat embolism syndrome is a diagnosis of exclusion and is based on clinical criteria. No specific sign, symptom, or test is pathognomonic. It may often be confused with other conditions such as systemic inflammatory response syndrome or sepsis. However, the triad of respiratory and neurologic symptoms and petechiae coupled with the clinical picture of recent trauma or orthopedic surgery almost assures the diagnosis.

Fat embolism syndrome can range from subclinical to fulminating, with the more fulminating course attributable to a huge load of fat emboli, which leads to acute cor pulmonale.

The diagnostic criteria established by Gurd and Wilson¹³ are widely accepted and include major, minor, and laboratory criteria (Table 3). According to their criteria, the diagnosis of fat embolism syndrome requires the presence of one major feature plus four minor features plus fat macroglobulinemia. Major signs appear in 60% of patients within 24 hours and in 85% of patients within 48 hours.¹³

Variations on these diagnostic guidelines require two major criteria, one major and three minor criteria, two major and two minor criteria, and one major and two minor criteria.³¹ Other authors, perceiving these criteria to be insensitive, have focused on other factors, including hypoxemia by arterial blood gas monitoring.^12,32 Lindeque at al¹² thus included arterial blood gas analysis in their criteria (Table 4). However, their criteria have been criticized for focusing only on the pulmonary system, and many of these features may be present in patients with ARDS with a cause other than fat embolization, such as burns, septicemia, aspiration, and multiple transfusions.

Schonfeld et al³² created a fat embolism index to diagnose fat embolism syndrome; a score greater than 5 indicates that the syndrome is likely (Table 5).³²

Regardless of the criteria used, one must have a high index of suspicion for fat embolization syndrome in patients undergoing orthopedic procedures, particularly hip and knee surgery, and in patients with fractures, especially fractures of the femur, tibia, or pelvis and multiple, concomitant fractures.

CASE CONTINUED

Our patient was given furosemide (Lasix) empirically for diuresis and to improve oxygenation. However, his oxygen saturation remained low.

Chest radiography 4 hours after surgery showed bilateral pulmonary infiltrates. Serial electrocardiography showed no acute changes. Levels of cardiac enzymes and troponins were normal. Transthoracic echocardiography showed no left ventricular dysfunction, a normal right ventricle, and no evidence of valvular lesions. Urine and blood fat stains were negative, but the sputum stain was positive for copious extracellular fat. The patient became comatose 5 hours postoperatively. Computed tomography of the brain was normal. He was transferred to the surgical intensive care unit.

The clinical course was marked by hemodynamic instability requiring norepinephrine (Levophed) and vasopressin (Pitressin) for hypotension. Right ventricular filling pressures via central venous pressure monitoring showed no evidence of hypovolemia. The hemoglobin concentration and the hematocrit were stable, with no evidence of acute or ongoing bleeding. Blood, urine, and sputum cultures remained negative. Acute myocardial infarction was ruled out by serial electrocardiography, cardiac enzyme testing, and troponin testing.

Magnetic resonance imaging (MRI) of the brain on postoperative day 2 showed foci of acute ischemia suggestive of embolic phenomena consistent with fat embolism syndrome (Figure  1). Transthoracic echocardiography was repeated but again showed no evidence of a patent foramen ovale. Electroencephalography on postoperative day 4 showed severe, diffuse encephalopathy. There was no petechial skin rash. Other laboratory studies showed progressive thrombocytopenia with a platelet count of 53 × 199/L on postoperative day 3.

 

TESTS THAT AID THE CLINICAL DIAGNOSIS

Although no single laboratory test is pathognomonic for fat embolism syndrome, several tests may help raise suspicion of it, especially in the setting of fracture or an orthopedic surgical procedure.

Arterial blood gases must be measured. A Pao₂ of less than 60 mm Hg with no other obvious lung pathology in an orthopedic surgery patient is highly suspicious.¹² An alveolar-arterial gradient of greater than 100 mm Hg may further increase suspicion.

Tests for fat. The blood and urine may be examined for fat, although positive findings are not specific for fat embolism syndrome.³³ Fat in the urine indicates the occurrence of massive fat embolism, but this is not always accompanied by the syndrome.³⁴ Gurd and Wilson¹³ found fat globules larger than 8 μm circulating in the serum in all documented cases. They stated that, even though the relationship of large fat globules to the pathogenesis of the clinical picture remains obscure, the demonstration of their presence can be helpful in the diagnosis.¹³

Also, samples obtained with bronchoalveolar lavage may be examined for fat. The macrophages may be stained for fat using the oil red O stain. Again, this is a nonspecific marker, as fat-stained macrophages are seen in trauma patients,³⁵ but the finding has a very high negative predictive value.³⁶ Anemia, thrombocytopenia, hypofibrinogenemia, an elevated lipase level, and a high erythrocyte sedimentation rate may be found in fat embolism syndrome.¹³

Chest radiography may show bilateral infiltrates, as in ARDS, but this is not diagnostic for fat embolism syndrome.

Electrocardiography may show changes in ST and T waves and signs of right heart strain.

Transesophageal echocardiography may show increased right heart and pulmonary artery pressures.

Computed tomography is often negative,^37,38 but T2-weighted MRI is useful in the diagnosis of cerebral fat embolism syndrome, as it can show intracerebral microinfarcts as early as 4 hours after the onset of neurologic symptoms, and these findings correlate well with the clinical severity of brain injury.

Diffusion-weighted MRI may enhance the sensitivity and specificity of the neuroradiologic diagnosis. Diffusion-weighted MRI typically shows multiple nonconfluent areas of high-intensity signals or bright spots on a dark background, known as a “starfield pattern.” This pattern has been suggested to be pathognomonic of acute cerebral microinfarction. The abnormalities presumably reflect foci of cytotoxic edema that develops immediately, unlike vasogenic edema, seen in T2-weighted images, which may take up to several days to develop. Although these images are not necessarily specific for fat emboli, they are useful in helping make the diagnosis. Thus, diffusionweighted MRI should be done if fat embolism syndrome is suspected.^38,39

CASE CONCLUDED

The patient’s course in the intensive care unit was further complicated by gastrointestinal bleeding and renal failure. His neurologic status did not improve. Repeated MRI of the brain showed evolving bilateral watershed infarction throughout the cortices. The neurologic consult service diagnosed the patient as having severe encephalopathy with a very poor prognosis. The decision was made to withdraw care. He was placed under palliative care and died on postoperative day 22.

DRUG TREATMENT OF FAT EMBOLISM SYNDROME

5. Which of the following drugs has been proven to be effective in treating fat embolism syndrome?

• Intravenous ethanol
• Steroids
• Heparin
• Dextran
• Aspirin
• None of the above

None of the above has been proven to be effective in treating this disorder. The management is largely supportive. Thus, prevention, early diagnosis, and symptom management are vital.

Pulmonary and hemodynamic support are the cornerstones of successful treatment. Aggressive respiratory support is often needed. Management of acute lung injury and ARDS focuses on achieving acceptable gas exchange while preventing ventilator-associated lung injury. Intravascular volume must be supported. Inotropes and pulmonary vasodilators may be required to maintain hemodynamics. Exacerbation of central nervous system ischemia from hypotension or hypoxia should be avoided.

If the thrombocytopenia leads to clinical bleeding, platelet transfusions may be warranted.

Supportive care should include prophylaxis of deep venous thrombosis and of gastrointestinal bleeding, and maintenance of nutrition.⁴⁰ Patients who receive supportive care generally have a favorable outcome, with a mortality rate of less than 10%.²⁸

Drug studies have been inconclusive

Drugs suggested in the treatment of fat embolism syndrome include heparin, aspirin, dextran, hypertonic glucose, and alcohol, but the results have been inconclusive.^{3,11,23,40–43}

Heparin stimulates lipase activity, consequently decreasing the concentration of circulating fat globules. However, the increase in levels of free fatty acids may actually worsen the clinical picture. For this reason, and because of anticoagulation concerns and evidence of increased mortality rates, heparin is now contraindicated in the treatment of fat embolism syndrome.^2,41,43

Alcohol. Patients with a higher blood alcohol level at the time of injury have been reported to have a lower incidence of fat embolism syndrome. Alcohol inhibits lipase, suppressing the rise of free fatty acids. In experimental studies, the incidence of fat embolism syndrome was lower when the blood alcohol level was maintained at 20 mg/dL. However, no prospective randomized trial has been done to determine the clinical efficacy of ethanol as a treatment for this condition.^5,42

Dextran has been advocated, owing to its ability to improve small-vessel perfusion, but bleeding risk and acute renal failure associated with this drug have limited its use.⁵

N-acetylcysteine has been shown to attenuate fat-induced lung injury in a study of rats with induced fat embolism syndrome.⁴⁴

Corticosteroid treatment for this condition is controversial. Studies in patients with femoral and tibial fractures show that steroids reduce the incidence of fat embolism syndrome when given prophylactically, and those treated with steroids had a higher Pao₂ than controls. Doses of methylprednisolone in these studies ranged between 9 mg/kg to 90 mg/kg. A drawback of these studies is their small number of patients.^12,32,45,46

A meta-analysis⁴⁷ of randomized trials of corticosteroids to prevent fat embolism syndrome in patients with long-bone fractures identified 104 such studies. Only 7 of the 104 were considered adequate. In 389 patients with long-bone fractures, prophylactic corticosteroids reduced the risk of fat embolism syndrome by 78% (95% confidence interval 43%–92%) and corticosteroids also significantly reduced the risk of hypoxia with no difference in rates of infection or death. However, the overall quality of the trials was poor, and the authors of the meta-analysis concluded that more study is needed before corticosteroids could be formally recommended.⁴⁷

There is no evidence that steroids improve the overall clinical course of already established fat embolism syndrome.^12,32,45 The dosing and optimal timing of administration have also not been established. High doses pose a risk of septic complications, which may be devastating for the posttrauma or postoperative patient.

A 75-year-old man with type 2 diabetes and hypothyroidism underwent bilateral total knee replacement at our hospital.

His functional capacity had been moderately limited by knee pain, but he could easily climb one flight of stairs without symptoms. His medications at that time included levothyroxine (Synthroid) and metformin (Glucophage). He had no known cardiac or pulmonary disease. The preoperative evaluation, including laboratory tests and electrocardiography, was within normal limits.

Spinal anesthesia was used for surgery, and he was given 2 mg of midazolam (Versed) intravenously for sedation. No additional sedation was given. He was given oxygen via nasal cannula at 2 L/min.

All vital signs were stable at the start of the procedure. However, about halfway through, when the thigh tourniquet was released, his oxygen saturation dropped abruptly from 100% to 92%. All other vital signs remained stable, and he was asymptomatic, was oriented to person, time, and place, was conversing freely, and was in no distress. The oxygen flow was increased to 6 L/min, his oxygen saturation improved, and the procedure was then completed as planned.

At the conclusion of the surgery, before the patient was transported to the postanesthesia care unit (PACU) and while his oxygen flow rate was still 6 L/min, his oxygen saturation again dropped to 92%. A simple face mask was placed, and the oxygen flow rate was increased to 10 L/min. His oxygen saturation stayed low, near 90%.

Bleeding during surgery had been nominal. He had received 2 L of lactated Ringer’s solution and 500 mL of hetastarch (Hextend) during surgery. He continued to be asymptomatic in the PACU.

1. What is the most likely cause of oxygen desaturation during bilateral total knee arthroplasty?

• Fat embolism
• Intraoperative pneumonia
• Venous thromboembolism with pulmonary embolism
• Acute myocardial infarction
• Acute pulmonary edema
• Excessive sedation

The differential diagnosis of oxygen desaturation during orthopedic procedures is listed in Table 1.

Fat embolism is the most likely cause, particularly given the greater fatty embolic load that occurs with bilateral total knee arthroplasty than with unilateral total knee arthroplasty.

At what point the maximal showering of fat emboli occurs is not known. Fat may be released into the circulation with pressurization of the medullary canal during surgery or with manipulation of a fracture. The emboli may collect in the leg veins and then be released in a shower when the thigh tourniquet is released. Vasoactive mediators and methylmethacrylate cement released into the circulatory system after tourniquet deflation may also cause vasodilation, hypotension, and increased dead-space ventilation, resulting in hypoxia and a drop in end-tidal CO₂.

Pneumonia during surgery is rare without an apparent aspiration event.

Venous thromboembolism is possible but is more likely later in the postoperative period after major orthopedic surgery.

Acute myocardial infarction could present with hypoxia, particularly in a diabetic patient, who may not experience chest pain. However, intraoperative electrocardiographic changes would likely be seen. If myocardial infarction is suspected, postoperative serial electrocardiograms and measuring troponin and cardiac enzyme levels aid in the diagnosis.

Acute pulmonary edema is possible but not as highly suspected, as the patient had no history of congestive heart failure and received an appropriate amount of fluid for this type of surgery.

Excessive sedation could cause hypoventilation and, thus, oxygen desaturatation. However, this patient’s oxygen desaturatation began more than an hour after the midazolam was given. Midazolam is a short-acting benzodiazepine. It is unlikely that the patient would show signs of hypoventilation and oversedation an hour after the drug was given. Our patient also did not show any signs of excessive sedation, as he was awake and conversing during the surgery.

Fat emboli vs fat embolism syndrome

Fat embolism is the presence of fat drops within the systemic and pulmonary microcirculation, with or without clinical sequelae.¹ Fat embolism syndrome, on the other hand, is defined as injury to and dysfunction of one or more organs as a result of the embolization of fat, usually within 24 hours of injury or orthopedic surgery.²

Fat embolism syndrome is an unpredictable condition with a varied presentation. Fat droplets are thought to embolize via the venous circulation into the pulmonary arteries, occluding small blood vessels in the lung. However, they also get into the arterial circulation and occlude arteries in the brain, kidney, heart, and liver (more on this phenomenon below).

Fat embolism is reported to originate primarily from fractures of the femur, tibia, and pelvis.^2,3 As many as 90% of trauma patients have been shown to have evidence of fat embolism on autopsy.⁴ However, only a small number of patients develop the classic fat embolism syndrome,^2,3,5 Why some develop the syndrome and others do not is still unknown.

Orthopedic procedures associated with fat embolization include knee arthroplasty and hip arthroplasty, particularly if it involves intramedullary manipulation or medullary fixation.⁶ It has also been reported during spinal procedures in which pedicular screws are used.⁷ The syndrome occurs in 0.25% to 30% of patients following multiple fractures and in 0.1% to 12% of patients during or following knee or hip arthroplasty.

One study⁸ showed evidence of fat on transesophageal echocardiography in 88% of patients undergoing medullary reaming of lower-extremity fractures and hip hemiarthroplasty. Blood sampling from the right atrium confirmed that fat was responsible for the echocardiographic abnormalities. The study also showed that the severity of the embolic showering correlated with the severity of hypoxia and the decrease in end-tidal CO₂.⁸

 

CASE CONTINUED

On arrival at the PACU, our patient’s oxygen saturation was 94% while he was breathing oxygen via a simple face mask at a flow rate of 10 L/min. His heart rate was 60 bpm, blood pressure 110/60 mm Hg, and temperature 37.5°C (96.3°F). Chest sounds were normal on auscultation.

However, 3 hours later, his mental status rapidly deteriorated. He was oriented only to person, and he was drowsy. He had escalating respiratory distress with a rapid respiratory rate and decreasing oxygen saturation. At this point, auscultation of his chest wall revealed bilateral crackles and rales.

He was promptly intubated. Profuse fluid and secretions were noted to be coming from his lungs, filling the endotracheal tube. Arterial blood gas measurement showed a pH of 7.22, Pao₂ 64 mm Hg, and Paco₂ 56 mm Hg on 100% fraction of inspired oxygen, with no increased anion gap.

2. Which consequence of fat embolism is most likely at this time in this patient?

• Coexisting sepsis
• Fat embolism syndrome
• Acute cardioembolic stroke
• Anaphylaxis

Fat embolism syndrome should be highly suspected in this patient. As mentioned, it can affect many different organs. It is the most serious condition resulting from fat embolization after surgery or trauma.

Sepsis was unlikely in our patient, since he presented for his surgery in good health and with no preexisting signs or symptoms of infection. Acute cardioembolic stroke could have caused the neurologic signs, but this would not necessarily explain the coexisting hypoxia. An anaphylactic reaction to drugs or surgical cement would most likely present intraoperatively, shortly after exposure occurred, rather than several hours after surgery.

How common is fat embolism syndrome?

The occurrence rate of fat embolism syndrome has been reported to be 0.25% to 30% after multiple fractures and 0.1% to 12% after knee and hip joint surgery, with a mortality rate of 13% to 36%.^2,9–14 The rate of occurrence after unilateral total knee joint replacement has been reported to be 1.8% to 5%, and 4% to 12% after bilateral total knee replacement.^15–19

The syndrome is relatively more common with traumatic fractures of the lower extremities. However, it has also been reported with liposuction, total parenteral nutrition, bone marrow harvest and transplantation, burns, and acute pancreatitis, to mention a few.¹⁰

The broad range of reported incidence rates can be attributed to the fact that many studies were in patients with multiple trauma, whose concomitant injuries may have made it difficult to clearly define the contribution of fat embolism syndrome to the overall rates of morbidity and mortality. Also, different studies used different criteria to define the syndrome.

How does fat embolism syndrome occur?

Two hypotheses for how this syndrome occurs were proposed nearly a century ago.^20,21

The “mechanical” theory is that fat emboli are formed as a result of trauma and disruption of adipose tissue and other cells in the bone marrow. Increases in intramedullary pressure force the fat emboli through damaged medullary venous channels in the bone and into the circulation of the lower extremities. This embolization of fat causes an initial mechanical pulmonary obstruction. Mechanical obstruction by fat emboli in the pulmonary system leads to increased pulmonary pressures and an increase in right heart outflow pressure. The right heart becomes strained, leading to a decreased right-sided cardiac output. As a result, the left heart filling pressures diminish and hypotension ensues.²⁰

The “biochemical” theory, on the other hand, is that chylomicrons within the vascular system are modified and their stability is compromised as a result of stress. These traumatized chylomicrons then coalesce to form droplets of fat that accumulate in the pulmonary circulation and produce a mechanical obstruction. This would explain why nontraumatic, nonorthopedic insults can produce this syndrome.

Autopsy studies show that there is little correlation between the presence and quantity of intravascular fat and the severity of clinical symptoms, thus implying that the syndrome is caused by more than just mechanical obstruction. The biochemical theory postulates that fat globules within the circulatory system then cause the release of lipase from the pulmonary alveolar cells, which then hydrolyses the fat into free fatty acids. These free fatty acids cause an inflammatory reaction, complementmediated leukocyte aggregation, chemotoxin release, and subsequently endothelial damage. These vasoactive substances damage type 2 pneumocytes and lead to an increased permeability of the pulmonary capillary beds. Acute respiratory distress syndrome (ARDS) may ensue. Disseminated intravascular coagulation may occur as a result of the formation of microthrombi involving lipids, platelets, and fibrin.^21,22

Embolization of fat to the central nervous system can occur as fat globules cross into the systemic circulation via a patent foramen ovale, an atrioventricular shunt, or the pulmonary capillaries. This can then result in cerebral ischemia.²³

Although patent foramen ovale may seem the most direct route for cerebral embolization, the neurologic impairment and signs of cerebral emboli in fat embolism syndrome may occur in the absence of patent foramen ovale.^24,25 The fat globules may actually go through the lung capillaries, being flexible and forced through by increased pulmonary pressure.

But whether the cause of fat embolism syndrome is occlusion by globules, the release of biochemical mediators, or a combination of both is unknown. Both mechanisms are likely responsible. We can only suspect that the degree of fat load and intrinsic metabolic differences between individuals account for the variation in susceptibility.

 

FAT EMBOLI AFFECT THE LUNGS, SKIN, AND BRAIN

3. Where on the body is the rash associated with fat embolism syndrome usually seen?

• Face
• Near a site of fracture or surgery
• Chest, axilla, conjunctiva
• Distal extremities

Petechiae are part of the classic presenting triad of fat embolism syndrome, which also includes pulmonary and cerebral dysfunction.

Petechiae usually appear on the 2nd to 4th day after injury.²⁶ They are usually found across the chest, the anterior axillary folds, and the neck, as well as on the oral mucosa and the conjunctiva. The rash is caused by occlusion of dermal capillaries by fat, which increases their fragility.¹⁰

Pulmonary changes usually begin with tachypnea, dyspnea, and a drop in oxygen saturation, leading to generalized hypoxia. Respiratory symptoms are present in 100% of cases.² Respiratory symptoms can acutely develop with the sudden manipulation of a fracture, reaming of bone, or release of a limb tourniquet.²⁷

Cerebral dysfunction can be variable, from anxiety and confusion to seizures and coma. The neurologic signs are typically diffuse; however, focal symptoms such as hemiplegia or aphasia can occasionally occur. Neurologic signs are present in 80% of cases.^2,28

Body systems affected by fat embolism syndrome are summarized in Table 2.

4. How many hours after injury does fat embolism syndrome typically manifest?

• 1 to 2 hours
• 6 to 12 hours
• 12 to 20 hours
• 24 to 48 hours
• 72 to 84 hours

Most patients develop signs and symptoms 24 to 48 hours after injury. Patients presenting earlier than 12 hours usually have a more fulminant course.²⁹

The time between fat embolization and the development of fat embolism syndrome is thought to be related to the time required for the metabolic conversion of fat to free fatty acids.³⁰ We suspect that the early desaturation seen in our patient was the result of a heavy showering of fat intraoperatively. However, this could only be concluded after we had ruled out other causes of acute hypoxia and hypotension.

Fat embolism syndrome is a diagnosis of exclusion and is based on clinical criteria. No specific sign, symptom, or test is pathognomonic. It may often be confused with other conditions such as systemic inflammatory response syndrome or sepsis. However, the triad of respiratory and neurologic symptoms and petechiae coupled with the clinical picture of recent trauma or orthopedic surgery almost assures the diagnosis.

Fat embolism syndrome can range from subclinical to fulminating, with the more fulminating course attributable to a huge load of fat emboli, which leads to acute cor pulmonale.

The diagnostic criteria established by Gurd and Wilson¹³ are widely accepted and include major, minor, and laboratory criteria (Table 3). According to their criteria, the diagnosis of fat embolism syndrome requires the presence of one major feature plus four minor features plus fat macroglobulinemia. Major signs appear in 60% of patients within 24 hours and in 85% of patients within 48 hours.¹³

Variations on these diagnostic guidelines require two major criteria, one major and three minor criteria, two major and two minor criteria, and one major and two minor criteria.³¹ Other authors, perceiving these criteria to be insensitive, have focused on other factors, including hypoxemia by arterial blood gas monitoring.^12,32 Lindeque at al¹² thus included arterial blood gas analysis in their criteria (Table 4). However, their criteria have been criticized for focusing only on the pulmonary system, and many of these features may be present in patients with ARDS with a cause other than fat embolization, such as burns, septicemia, aspiration, and multiple transfusions.

Schonfeld et al³² created a fat embolism index to diagnose fat embolism syndrome; a score greater than 5 indicates that the syndrome is likely (Table 5).³²

Regardless of the criteria used, one must have a high index of suspicion for fat embolization syndrome in patients undergoing orthopedic procedures, particularly hip and knee surgery, and in patients with fractures, especially fractures of the femur, tibia, or pelvis and multiple, concomitant fractures.

CASE CONTINUED

Our patient was given furosemide (Lasix) empirically for diuresis and to improve oxygenation. However, his oxygen saturation remained low.

Chest radiography 4 hours after surgery showed bilateral pulmonary infiltrates. Serial electrocardiography showed no acute changes. Levels of cardiac enzymes and troponins were normal. Transthoracic echocardiography showed no left ventricular dysfunction, a normal right ventricle, and no evidence of valvular lesions. Urine and blood fat stains were negative, but the sputum stain was positive for copious extracellular fat. The patient became comatose 5 hours postoperatively. Computed tomography of the brain was normal. He was transferred to the surgical intensive care unit.

The clinical course was marked by hemodynamic instability requiring norepinephrine (Levophed) and vasopressin (Pitressin) for hypotension. Right ventricular filling pressures via central venous pressure monitoring showed no evidence of hypovolemia. The hemoglobin concentration and the hematocrit were stable, with no evidence of acute or ongoing bleeding. Blood, urine, and sputum cultures remained negative. Acute myocardial infarction was ruled out by serial electrocardiography, cardiac enzyme testing, and troponin testing.

Magnetic resonance imaging (MRI) of the brain on postoperative day 2 showed foci of acute ischemia suggestive of embolic phenomena consistent with fat embolism syndrome (Figure  1). Transthoracic echocardiography was repeated but again showed no evidence of a patent foramen ovale. Electroencephalography on postoperative day 4 showed severe, diffuse encephalopathy. There was no petechial skin rash. Other laboratory studies showed progressive thrombocytopenia with a platelet count of 53 × 199/L on postoperative day 3.

 

TESTS THAT AID THE CLINICAL DIAGNOSIS

Although no single laboratory test is pathognomonic for fat embolism syndrome, several tests may help raise suspicion of it, especially in the setting of fracture or an orthopedic surgical procedure.

Arterial blood gases must be measured. A Pao₂ of less than 60 mm Hg with no other obvious lung pathology in an orthopedic surgery patient is highly suspicious.¹² An alveolar-arterial gradient of greater than 100 mm Hg may further increase suspicion.

Tests for fat. The blood and urine may be examined for fat, although positive findings are not specific for fat embolism syndrome.³³ Fat in the urine indicates the occurrence of massive fat embolism, but this is not always accompanied by the syndrome.³⁴ Gurd and Wilson¹³ found fat globules larger than 8 μm circulating in the serum in all documented cases. They stated that, even though the relationship of large fat globules to the pathogenesis of the clinical picture remains obscure, the demonstration of their presence can be helpful in the diagnosis.¹³

Also, samples obtained with bronchoalveolar lavage may be examined for fat. The macrophages may be stained for fat using the oil red O stain. Again, this is a nonspecific marker, as fat-stained macrophages are seen in trauma patients,³⁵ but the finding has a very high negative predictive value.³⁶ Anemia, thrombocytopenia, hypofibrinogenemia, an elevated lipase level, and a high erythrocyte sedimentation rate may be found in fat embolism syndrome.¹³

Chest radiography may show bilateral infiltrates, as in ARDS, but this is not diagnostic for fat embolism syndrome.

Electrocardiography may show changes in ST and T waves and signs of right heart strain.

Transesophageal echocardiography may show increased right heart and pulmonary artery pressures.

Computed tomography is often negative,^37,38 but T2-weighted MRI is useful in the diagnosis of cerebral fat embolism syndrome, as it can show intracerebral microinfarcts as early as 4 hours after the onset of neurologic symptoms, and these findings correlate well with the clinical severity of brain injury.

Diffusion-weighted MRI may enhance the sensitivity and specificity of the neuroradiologic diagnosis. Diffusion-weighted MRI typically shows multiple nonconfluent areas of high-intensity signals or bright spots on a dark background, known as a “starfield pattern.” This pattern has been suggested to be pathognomonic of acute cerebral microinfarction. The abnormalities presumably reflect foci of cytotoxic edema that develops immediately, unlike vasogenic edema, seen in T2-weighted images, which may take up to several days to develop. Although these images are not necessarily specific for fat emboli, they are useful in helping make the diagnosis. Thus, diffusionweighted MRI should be done if fat embolism syndrome is suspected.^38,39

CASE CONCLUDED

The patient’s course in the intensive care unit was further complicated by gastrointestinal bleeding and renal failure. His neurologic status did not improve. Repeated MRI of the brain showed evolving bilateral watershed infarction throughout the cortices. The neurologic consult service diagnosed the patient as having severe encephalopathy with a very poor prognosis. The decision was made to withdraw care. He was placed under palliative care and died on postoperative day 22.

DRUG TREATMENT OF FAT EMBOLISM SYNDROME

5. Which of the following drugs has been proven to be effective in treating fat embolism syndrome?

• Intravenous ethanol
• Steroids
• Heparin
• Dextran
• Aspirin
• None of the above

None of the above has been proven to be effective in treating this disorder. The management is largely supportive. Thus, prevention, early diagnosis, and symptom management are vital.

Pulmonary and hemodynamic support are the cornerstones of successful treatment. Aggressive respiratory support is often needed. Management of acute lung injury and ARDS focuses on achieving acceptable gas exchange while preventing ventilator-associated lung injury. Intravascular volume must be supported. Inotropes and pulmonary vasodilators may be required to maintain hemodynamics. Exacerbation of central nervous system ischemia from hypotension or hypoxia should be avoided.

If the thrombocytopenia leads to clinical bleeding, platelet transfusions may be warranted.

Supportive care should include prophylaxis of deep venous thrombosis and of gastrointestinal bleeding, and maintenance of nutrition.⁴⁰ Patients who receive supportive care generally have a favorable outcome, with a mortality rate of less than 10%.²⁸

Drug studies have been inconclusive

Drugs suggested in the treatment of fat embolism syndrome include heparin, aspirin, dextran, hypertonic glucose, and alcohol, but the results have been inconclusive.^{3,11,23,40–43}

Heparin stimulates lipase activity, consequently decreasing the concentration of circulating fat globules. However, the increase in levels of free fatty acids may actually worsen the clinical picture. For this reason, and because of anticoagulation concerns and evidence of increased mortality rates, heparin is now contraindicated in the treatment of fat embolism syndrome.^2,41,43

Alcohol. Patients with a higher blood alcohol level at the time of injury have been reported to have a lower incidence of fat embolism syndrome. Alcohol inhibits lipase, suppressing the rise of free fatty acids. In experimental studies, the incidence of fat embolism syndrome was lower when the blood alcohol level was maintained at 20 mg/dL. However, no prospective randomized trial has been done to determine the clinical efficacy of ethanol as a treatment for this condition.^5,42

Dextran has been advocated, owing to its ability to improve small-vessel perfusion, but bleeding risk and acute renal failure associated with this drug have limited its use.⁵

N-acetylcysteine has been shown to attenuate fat-induced lung injury in a study of rats with induced fat embolism syndrome.⁴⁴

Corticosteroid treatment for this condition is controversial. Studies in patients with femoral and tibial fractures show that steroids reduce the incidence of fat embolism syndrome when given prophylactically, and those treated with steroids had a higher Pao₂ than controls. Doses of methylprednisolone in these studies ranged between 9 mg/kg to 90 mg/kg. A drawback of these studies is their small number of patients.^12,32,45,46

A meta-analysis⁴⁷ of randomized trials of corticosteroids to prevent fat embolism syndrome in patients with long-bone fractures identified 104 such studies. Only 7 of the 104 were considered adequate. In 389 patients with long-bone fractures, prophylactic corticosteroids reduced the risk of fat embolism syndrome by 78% (95% confidence interval 43%–92%) and corticosteroids also significantly reduced the risk of hypoxia with no difference in rates of infection or death. However, the overall quality of the trials was poor, and the authors of the meta-analysis concluded that more study is needed before corticosteroids could be formally recommended.⁴⁷

There is no evidence that steroids improve the overall clinical course of already established fat embolism syndrome.^12,32,45 The dosing and optimal timing of administration have also not been established. High doses pose a risk of septic complications, which may be devastating for the posttrauma or postoperative patient.

A 37-year-old man presented to the emergency department with an 8-week history of a mildly productive cough and shortness of breath accompanied by high fevers, chills, and night sweats. He also had some nausea but no vomiting.

Four days earlier, he had been evaluated by his primary care physician, who prescribed a 14-day course of one double-strength trimethoprim-sulfamethoxazole tablet (Bactrim DS) every 12 hours for presumed acute bronchitis, but his symptoms did not improve.

He was unemployed, living in Arizona, married with children. He denied any use of tobacco, alcohol, or injection drugs. On further questioning, he disclosed that he had unintentionally lost 30 pounds over the past 2 to 3 months and had been feeling tired.

When asked about his medical history, he revealed that he had been diagnosed with human immunodeficiency virus (HIV) infection in 2008 and that recently he had not been taking his antiretroviral medication, a once-daily combination pill containing efavirenz, emtricitabine, and tenofovir (Atripla). He had no other significant medical history, and the only medication he was currently taking was the trimethoprim-sulfamethoxazole.

On examination, his temperature was 38.7°C (101.7°F), blood pressure 109/68 mm Hg, heart rate 60 beats per minute, respiratory rate 18 breaths per minute, and oxygen saturation 100% while breathing supplemental oxygen via nasal cannula at 2 L/min. He did not appear seriously ill.

His mucous membranes were moist, and he did not have oral candidiasis. He had a palpable 1-cm nontender lymph node above his left clavicle. His heart and lungs were normal on physical examination. He had normal bowel sounds and no signs of peritonitis. His liver and spleen did not seem enlarged. Neurologic examination demonstrated normal cranial nerves, strength, reflexes, and sensation in all four limbs.

Initial blood tests (Table 1) showed a normal white blood cell count, normal results on a complete metabolic panel, and a lactate dehydrogenase level of 539 IU/L (reference range 313–618). His serum lactate level was within normal limits.

A chest radiograph showed multiple pulmonary nodules and a cavity in the lingula (Figure 1). In view of these findings, the patient was admitted to the hospital for further evaluation and testing.

HIV-specific tests performed on the second day of hospitalization showed extreme immunosuppression, with a CD4 count of 5 cells/μL (normal 326–1,404 cells/μL).

WHICH ORGANISM IS CAUSING HIS LUNG INFECTION?

1. Which of the following organisms is the least likely to be associated with this patient’s condition?

• Mycobacterium tuberculosis
• Pneumocystis jirovecii
• Coccidioides immitis
• Candida albicans
• Streptococcus pneumoniae
• Cytomegalovirus

Bacterial, fungal, and viral lung infections are common in HIV-infected patients, especially if they are not on antiretroviral therapy and their CD4 lymphocyte counts are low. Clues to the cause can be derived from the history, physical examination, and general laboratory studies. For instance, knowing where the patient lives and where he has travelled recently provides insight into exposure to endemic infectious agents.

The complete blood cell count with differential white blood cell count can help narrow the differential diagnosis but rarely helps exclude a possibility. Neutrophilia is common in bacterial infections. Lymphocytosis can be seen in tuberculosis, in fungal and viral infections, and, rarely, in hematologic malignancies. Eosinophilia can be seen in acute retroviral syndrome, fungal and helminthic infections, adrenal insufficiency, autoimmune disease, and lymphoma.

A caveat to these clues is that in severely immunocompromised hosts, like this man, diagnoses should not be excluded without firm evidence. This patient has severe, active immunosuppression, and only one of the six answer choices above is not a possible causative agent: C albicans rarely causes lung infection, even in immunocompromised people.

Mycobacterium tuberculosis

Tuberculosis can be the first manifestation of HIV infection. It can occur at any CD4 count, but as the count decreases, the risk of dissemination increases.¹ Classic symptoms are fever, night sweats, hemoptysis, and weight loss.

The CD4 count also affects the radiographic presentation. If the count is higher than 350 cells/μL, then infiltration of the upper lobe is likely; if it is lower than 200 cells/μL, then middle, lower, miliary, and extrapulmonary manifestations are likely.^1,2 Cavitation is less common in HIV-infected patients, but mediastinal adenopathy is more common.¹

Definitive diagnosis is via sputum examination, blood culture, nucleic acid amplification, or microscopic study of biopsy specimens of affected tissues to look for acid-fast bacilli.¹

Interferon-gamma-release assays such as the QuantiFERON test (Cellestis, Valencia, CA) or a tuberculin skin test can be used to check for latent tuberculosis infection. These tests can also provide evidence of active infection in the appropriate clinical context.³

Interferon-gamma-release assays have several advantages over skin testing: they are more sensitive (76% to 80%) and specific (97%); they do not give false-positive results in people who previously received bacille Calmette-Guérin vaccine; they react only minimally to previous exposure to nontuberculous mycobacteria; and interpretation is not subject to interreader variability.^4,5 However, concordance between skin testing and interferon-gamma-release assays is low. Therefore, either or both tests can be used if tuberculosis is strongly suspected, and a positive result on either test should prompt further workup.^6,7

Of note, both tests may be affected by immunosuppression, making both susceptible to false-negative results as the CD4 count declines.³

In any case, a positive acid-fast bacillus smear, radiographic evidence of latent infection, or pulmonary symptoms should be presumed to represent active tuberculosis. In such a situation, directly observed treatment with the typical four-drug regimen—rifampin (Rifadin), isoniazid, pyrazinamide, and ethambutol (Myambutol)—is recommended while awaiting definitive results from culture or polymerase chain reaction (PCR) testing.¹

 

 

Pneumocystis jirovecii

P jirovecii was previously known as P carinii, and P jirovecii pneumonia is an AIDS-defining illness. Most cases occur when the CD4 count falls below 200 cells/μL.¹ Symptoms, including a nonproductive cough, develop insidiously over days to weeks.

Physical examination may reveal inspiratory crackles; however, half of the time the physical examination is nondiagnostic. Oral candidiasis is a common coinfection. The lactate dehydrogenase level may be elevated.^1,8 Radiographs show bilateral interstitial infiltrates, and in 10% to 20% of patients lung cysts develop—hence the name of the organism.¹ Pneumothorax in a patient with HIV should prompt a workup for P jirovecii pneumonia.^9,10

No consensus exists for the diagnosis. However, if sputum examination is unrevealing but suspicion is high, then bronchoalveolar lavage can help.^11–13

Trimethoprim-sulfamethoxazole for 21 days is the first-line treatment, with glucocorticoids added if the Pao₂ is less than 70 mm Hg or if the alveolar-arterial oxygen gradient is greater than 35 mm Hg.¹

Coccidioides species

Coccidioides infection is typically due to either C immitis or C posadasii.¹⁴ People living in or travelling to areas where it is endemic, such as the southwestern United States, Mexico, and Central and South America, are at higher risk.¹⁴

Typical signs and symptoms of this fungal infection include an influenza-like illness with fever, cough, adenopathy, and wasting, and when combined with erythema nodosum, erythema multiforme, arthralgia, or ocular involvement, this constellation is colloquially termed “valley fever.”¹⁵ Most HIV-infected patients who have CD4 counts higher than 250 cells/μL present with focal pneumonia, while lower counts predispose to disseminated disease.^1,2,16

Findings on examination are nonspecific and depend on the various pulmonary manifestations, which include acute, chronic progressive, or diffuse pneumonia, nodules, or cavities.¹⁴ Eosinophilia may accompany the infection.¹⁵

The diagnosis can be made by finding the organisms on direct microscopic examination of involved tissues or secretions or on culture of clinical specimens.^1,2,14 Serologic tests, antigen detection tests, or culture can be helpful if positive, but negative results do not rule out the diagnosis.^1,2,14

A caveat about testing: if the pretest probability of infection is low, positive tests for immunoglobulin M (IgM) do not necessarily equal infection, and the IgM test should be followed up with confirmatory testing. Along the same lines, a high pretest probability should not be ignored if initial tests are negative, and patients in this situation should also undergo further evaluation.¹⁷

Therapy with an azole drug such as fluconazole (Diflucan) or one of the amphotericin B preparations should be started, depending on the severity of the disease.^1,2,14,18

Candida albicans

C albicans is a rare cause of lung infection.^19,20 It is, however, a common inhabitant of the upper airway tract, and pulmonary infection is usually the result of aspiration or hematogenous spread from either the gastrointestinal tract or an infected central venous catheter.²⁰

The presentation is relatively nonspecific. Fever despite broad-spectrum antibacterial therapy is a major clue. Radiographic abnormalities usually are due to other causes, such as superimposed infections or pulmonary hemorrhage.²¹ Sputum culture is unreliable because of colonization. The definitive diagnosis is based on lung biopsy demonstrating organisms within the tissue.^19,20,22

Therapy with a systemic antifungal agent is recommended.

Streptococcus pneumoniae

S pneumoniae is one of the most common bacterial causes of community-acquired pneumonia in people with or without HIV.^23–25 Moreover, two or more episodes of bacterial pneumonia in 12 months can be an AIDS-defining condition in patients with a positive serologic test for HIV.¹⁶ Therefore, in patients with fever, cough, and pulmonary infiltrates on chest radiography, S pneumoniae must always be considered.

Urinary antigen testing has a relatively high positive predictive value (> 89%) and specificity (96%) for diagnosing S pneumoniae pneumonia.²⁶ Blood and sputum cultures should be done not only to confirm the diagnosis, but also because the rates of bacteremia and drug resistance are higher with S pneumoniae infection in the HIV-infected.¹

A combination of a beta-lactam and a macrolide or respiratory fluoroquinolone is the treatment of choice.¹

Cytomegalovirus

Although influenza is the most common cause of viral pneumonia in HIV-infected people, cytomegalovirus is an opportunistic cause.² This is usually a reactivation of latent infection rather than new infection.²⁷ Typically, infections occur at CD4 counts lower than 50 cells/μL, with cough, dyspnea, and fever that last for 2 to 4 weeks.²

Crackles may be heard on lung examination. The lactate dehydrogenase level can be elevated, as in P jirovecii pneumonia.² Radiography can show a wide range of nonspecific findings, from reticular and ground-glass opacities to alveolar or interstitial infiltrates to nodules.

The diagnosis of cytomegalovirus pneumonia is not always clear. Since HIV-infected patients typically shed the virus in their airways, bronchoalveolar lavage is not adequate because a positive finding does not necessarily mean the patient has active viral pneumonitis.²⁷ For this reason, infection should be confirmed by biopsy demonstrating characteristic cytomegalovirus inclusions in lung tissue.²

Importantly, once cytomegalovirus pneumonia is confirmed, the patient should be screened for cytomegalovirus retinitis even if he or she has no visual symptoms, as cytomegalovirus pneumonitis is typically a part of a disseminated infection.¹

Treatment with intravenous ganciclovir (Cytovene) is required.¹

CASE CONTINUED: POSITIVE TESTS FOR COCCIDIOIDES

Our patient began empiric treatment for community-acquired pneumonia with intravenous ceftriaxone (Rocephin) and azithromycin (Zithromax).

He underwent computed tomography (CT) with contrast to further characterize the abnormal findings on chest radiography. This revealed a lingular cavitary airspace consolidation, 1- to 1.2-cm pulmonary nodules scattered throughout both lungs, and mediastinal lymphadenopathy (Figure 2).

On the basis of these findings, the patient was immediately placed in negative pressure respiratory isolation and underwent induced sputum examinations for tuberculosis. Further tests for S pneumoniae, S aureus, Mycoplasma, Legionella, influenza, Pneumocystis, Cryptococcus, Histoplasma, and Coccidioides species were performed.

QuantiFERON testing was negative, and blood cultures were sterile. The first induced sputum examination was negative for acid-fast bacilli. PCR testing for mycobacterial DNA in the sputum was also negative.

Both silver and direct fluorescent antibody staining of the sputum were negative for Pneumocystis. On the basis of these findings and the patient’s lack of clinical improvement with trimethoprim-sulfamethoxazole, Pneumocystis infection was excluded.

PCR testing of nasopharyngeal samples for influenza A and B was negative. Tests for S pneumoniae, S aureus, Mycoplasma, Legionella, influenza, Crypotococcus, and Histoplasma were also negative. However, sputum cytology revealed characteristic spherules consistent with coccidioidomycosis (Figure 3). The patient’s coccidioidal serologic tests with immunodiffusion and complement fixation returned negative, presumably because of his immunocompromised state. However, an enzymelinked immunoassay for urinary coccidioidal antigen (MiraVista Diagnostics, Indianapolis, IN), with a sensitivity of 71% and a specificity of 99%, was elevated at 5.15 ng/mL (reference range 0.07–2.0). Based on these findings and those on chest CT, the diagnosis of coccidioidomycosis was confirmed. Treatment needed to be started.

 

THE PATIENT BEGINS TREATMENT

2. Which treatment is most appropriate for this patient?

• Posaconazole (Noxafil)
• Caspofungin (Cancidas) and surgery
• Fluconazole
• Voriconazole (Vfend) and surgery
• Amphotericin B

Asymptomatic pulmonary coccidioidomycosis in an immunocompetent patient requires only supportive care. However, if the infection is symptomatic, severe (Table 2), or in an immunocompromised host, antifungal treatment is indicated.^1,18

Solitary pulmonary cavities tend to be asymptomatic and do not require treatment, even if coccidioidal infection is microbiologically confirmed.

However, if there is pain, hemoptysis, or bacterial superinfection, antifungal therapy may result in improvement but not closure of the cavity.¹⁸ Therefore, in all cases of symptomatic coccidioidal pulmonary cavities, surgical resection is the only definitive treatment.

Coccidioidal cavities may rupture and cause pyopneumothorax, but this is an infrequent complication, and antifungal therapy combined with surgical decortication is the treatment of choice.¹⁸

Commonly prescribed antifungals include fluconazole and amphotericin B, the latter usually reserved for patients with significant hypoxia or rapid clinical deterioration.¹⁸ At this time, there are not enough clinical data to show that voriconazole or posaconazole is effective, and thus neither is approved for the treatment of coccidioidomycosis. Likewise, there have been no human trials of the efficacy of caspofungin against Coccidioides infection, although it has been shown to be active in mouse models.¹⁸

Our patient was started on oral fluconazole and observed for clinical improvement or, conversely, for signs of dissemination. After 2 days, he had markedly improved, and within 1 week he was almost back to his baseline level of health. Testing for all other infectious etiologies was unrevealing, and he was removed from negative pressure isolation.

However, as we mentioned above, his CD4 count was 5 cells/μL. We discussed the issue with the patient, and he said he was willing to comply with his treatment for both his Coccidioides and his HIV infection. After much deliberation, he said he was also willing to start and comply with prophylactic treatment for opportunistic infections.

PREVENTING OPPORTUNISTIC INFECTIONS IN HIV PATIENTS

3. Which of the following prophylactic regimens is most appropriate for this patient?

• Trimethoprim-sulfamethoxazole, atovaquone (Mepron), and azithromycin
• Trimethoprim-sulfamethoxazole and azithromycin
• Pentamidine (Nebupent), dapsone, and clarithromycin (Biaxin)
• Dapsone and clarithromycin
• Trimethoprim-sulfamethoxazole by itself

According to guidelines for the prevention of opportunistic diseases in patients with HIV, he needs primary prophylaxis against the following organisms: P jirovecii, Toxoplasma gondii, and Mycobacterium avium complex.¹

The CD4 count dictates the appropriate time to start therapy. If the count is lower than 200 cells/μL or if the patient has oropharyngeal candidiasis regardless of the CD4 count, trimethoprim-sulfamethoxazole is indicated to prevent P jirovecii pneumonia. In those who cannot tolerate trimethoprim-sulfamethoxazole or who are allergic to it, dapsone, pentamidine, or atovaquone can be substituted.¹

In patients seropositive for T gondii, a CD4 count lower than 100/μL indicates the need for prophylaxis.¹ Prophylactic measures are similar to those for Pneumocystis. However, if the patient cannot tolerate trimethoprim-sulfamethoxazole, the recommended alternative is dapsone-pyrimethamine with leucovorin, which is also effective against Pneumocystis.¹

Finally, if the CD4 count is lower than 50 cells/μL, prophylaxis against M avium complex is mandatory, with either azithromycin weekly or clarithromycin daily.¹

Given our patient’s degree of immunosuppression, trimethoprim-sulfamethoxazole plus azithromycin is his most appropriate option.

Trimethoprim-sulfamethoxazole and azithromycin were added to his antimicrobial regimen before he was discharged. Two weeks later, he noted no side effects from any of the medications, he had no new symptoms, he was feeling well, and his cough had improved greatly. He did not have any signs of dissemination of his coccidioidal infection, and we concluded that the primary and only infection was located in the lungs.

DISSEMINATED COCCIDIOIDOMYCOSIS

4. Which of the following extrapulmonary sites is Coccidioides least likely to infect?

• Brain
• Skin
• Meninges
• Lymph nodes
• Bones
• Joints

Extrapulmonary coccidioidomycosis can involve almost any site. However, the most common sites of dissemination are the skin, lymph nodes, bones, and joints.¹⁴ The least likely site is the brain.

Central nervous system involvement

In the central nervous system, involvement is typically with the meninges, rather than frank involvement of the brain parenchyma.^18,28,29 Although patients with HIV or those who are otherwise severely immunocompromised are at higher risk for coccidioidal meningitis, it is rare even in this population.^30,31 Meningitis most commonly presents as headache, vomiting, meningismus, confusion, or diplopia.^32,33

If neurologic findings are absent, experts do not generally recommend lumbar puncture because the incidence of meningeal involvement is low. When cerebrospinal fluid is obtained in an active case of coccidioidal meningitis, fluid analysis typically finds elevated protein, low glucose, and lymphocytic pleocytosis.^1,32

Meningeal enhancement on CT or magnetic resonance imaging is common.³⁴ The diagnosis is established by culture or serologic testing of cerebrospinal fluid (IgM titer, IgG titer, immunodiffusion, or complement fixation).¹⁴

Of note, cerebral infarction and hydrocephalus are feared complications and pose a serious risk of death in any patient.^32,35 In these cases, treatment with antifungals is lifelong, regardless of immune system status.¹⁸

Skin involvement

Skin involvement is variable, consisting of nodules, verrucae, abscesses, or ulcerations.^15,16 Hemorrhage from the skin is relatively common.³⁶ From the skin, the infection can spread to the lymph nodes, leading to regional lymphadenopathy.^14,15 Nodes can ulcerate, drain, or even become necrotic.

Bone and joint involvement

Once integrity of the blood vessels is disrupted, Coccidioides can spread via the blood to the bones or joints,^14,15 causing osteomyelitis, septic arthritis, or synovitis. Subcutaneous abscesses or sinus tracts may subsequently develop.^14,15

 

HOW LONG MUST HE BE TREATED?

On follow-up, the patient asked how long he needed to continue his antifungal regimen and if any other testing for his coccidioidal infection was necessary, since he was feeling better.

5. Which is the most appropriate response to the patient’s question?

• He can discontinue his antifungal drugs; no further testing is necessary
• He needs 14 more days of antifungal therapy and periodic serologic tests
• He needs 2.5 more months of antifungal therapy and monthly blood cultures
• He needs lifelong antifungal therapy and periodic urinary antigen levels
• He needs 5.5 more months of antifungal therapy; bronchoscopy with bronchoalveolar lavage at 1 year

How long to treat and how to monitor for coccidioidomycosis vary by patient.

Duration of therapy depends on symptoms and immune status

The severity of infection (Table 2) and the immune status are important factors that must be considered when tailoring a therapeutic regimen.

Immunocompetent patients without symptoms or with mild symptoms usually do not need therapy and are followed periodically for signs of improvement.^14,18,29

Immunocompetent patients with severe symptoms typically receive 3 to 6 months of antifungal therapy.¹⁸

Immunocompromised patients (especially HIV-infected patients with CD4 counts < 250 cells/μL) need antifungal treatment, regardless of the severity of infection.^14,18,29 In many cases, the type of infection will dictate the duration of therapy.

Diffuse pneumonia or extrapulmonary dissemination typically requires treatment for at least 1 year regardless of immune status.^14,18 For those with HIV and diffuse pneumonia, dissemination, or meningitis, guidelines dictate that secondary prophylaxis be started after at least 1 year of therapy and improvement in clinical status; it should be continued indefinitely to prevent reactivation of latent infection.¹⁸

The guidelines say that in patients with higher CD4 counts (presumably > 250 cells/μL) and nonmeningeal coccidioidomycosis, providers may consider discontinuing secondary prophylaxis, as long as there is clinical evidence of improvement and control of the primary infection.¹⁸ However, many experts advocate continuing secondary prophylaxis regardless of the CD4 count, as the rates of relapse and dissemination are high.^1,16,37

Monitoring

Regardless of the therapy chosen, disease monitoring every 2 to 4 months with clinical history and examination, radiography, and coccidioidal-specific testing is recommended for at least 1 year, and perhaps longer, to ensure complete resolution and to monitor for signs of dissemination.^14,18

Which test to use is not clear. Serologic testing identifies antibodies (IgM or IgG) to coccidioidal antigens. IgM appears during the acute infection, and tests include immunodiffusion, latex agglutination, and enzymelinked immunoassays. The last two are highly sensitive but have a significant false-positive rate, and should be confirmed with the former if found to be positive.^17,18 IgG appears weeks after the acute infection and can be evaluated with immunodiffusion or enzyme-linked immunoassay as well.

Keep in mind that these tests provide only qualitative results on the presence of these antibodies, not quantitative information. Furthermore, enzyme-linked immunoassay is not as accurate as immunodiffusion, which has a sensitivity in immunocompromised patients of only approximately 50%.^38,39

For that reason, complement fixation titers are extremely helpful because they reflect the severity of infection, can be used to monitor the response to treatment, and can even provide insight into the prognosis.¹⁸ The sensitivity of this test in immunocompromised hosts is 60% to 70%.³⁸ Titers can be checked to confirm the diagnosis and can be periodically monitored throughout the treatment course to ensure efficacy of therapy and to watch for reactivation of the infection.¹ In fact, an initial complement fixation titer of 1:2 or 1:4 is associated with favorable outcomes, while a titer greater than 1:16 portends dissemination.¹⁸

The caveat to any serologic test (immunodiffusion, enzyme-linked immunoassay, and complement fixation) is that severely immunocompromised patients (as in our case) may not mount an immune response and may have falsely low titers even in the face of a severe infection, and therefore these tests may not be reliable.³⁸ In these situations, urinary coccidioidal antigen detection assay (sensitivity 71%) or nucleic acid amplification of coccidioidal DNA (sensitivity 75%) may be of more help.^40,41

Therefore, in the setting of HIV infection, an asymptomatic pulmonary cavity, and diffuse pulmonary involvement secondary to coccidioidal infection, lifelong antibiotics (treatment plus secondary prophylaxis) with periodic testing of urinary coccidioidal antigen levels is the best response to the patient’s question, given that his complement fixation titers were initially negative and antigen levels were positive.

CASE CONCLUDED

The patient continues to be followed for his HIV infection. He is undergoing serologic and urinary antigen testing for Coccidioides infection every 3 months in addition to his maintenance HIV testing. He is on chronic suppressive therapy with fluconazole. He has not had a recurrence of his Coccidioides infection, nor have there been any signs of dissemination.

CAVITARY LUNG LESIONS IN HIV PATIENTS

In patients with HIV, cavitary lung lesions on chest radiography can be due to a wide variety of etiologies that range from infection to malignancy. Historical clues, including environmental exposure, occupation, geographic residence, sick contacts, travel, or animal contact can be helpful in ordering subsequent confirmatory testing, especially in the case of infection.

Tuberculosis should be suspected, and appropriate isolation precautions should be taken until it is ruled out.

Laboratory testing, including the complete blood cell count with differential and CD4 count, provide ancillary data to narrow the differential diagnosis. For example, if the CD4 count is greater than 200 cells/μL, mycobacterial infection should be strongly suspected; however, lower CD4 counts should also prompt a search for opportunistic infections. In the appropriate clinical scenario, malignancies including Kaposi sarcoma, non-Hodgkin lymphoma, and bronchogenic carcinoma can be seen and should also be considered.

Nevertheless, the evaluation hinges on the sputum examination and CT scan of the chest to further characterize the cavity, surrounding lung parenchyma, lymph nodes, and potential fluid collections. Usually, further serologic tests and even bronchoscopy with bronchoalveolar lavage and transbronchial biopsy are required. Treatment should begin once the most likely diagnosis is established.

Coccidioidal pneumonia should be considered in all patients with immunodeficiency, including HIV patients, transplant recipients, those undergoing chemotherapy, and those with intrinsic immune system defects, especially if they have a history of exposure or if they are from an endemic region. Antifungal therapy should be initiated early, and dissemination must be ruled out. Suppressive therapy is mandatory for those with a severely compromised immune system, and serologic testing to ensure remission of the infection is needed. Patients who were previously exposed to Coccidioides or who vacationed or live in the southwestern United States (where it is prevalent) are at risk and may present with any number of symptoms.

A 37-year-old man presented to the emergency department with an 8-week history of a mildly productive cough and shortness of breath accompanied by high fevers, chills, and night sweats. He also had some nausea but no vomiting.

Four days earlier, he had been evaluated by his primary care physician, who prescribed a 14-day course of one double-strength trimethoprim-sulfamethoxazole tablet (Bactrim DS) every 12 hours for presumed acute bronchitis, but his symptoms did not improve.

He was unemployed, living in Arizona, married with children. He denied any use of tobacco, alcohol, or injection drugs. On further questioning, he disclosed that he had unintentionally lost 30 pounds over the past 2 to 3 months and had been feeling tired.

When asked about his medical history, he revealed that he had been diagnosed with human immunodeficiency virus (HIV) infection in 2008 and that recently he had not been taking his antiretroviral medication, a once-daily combination pill containing efavirenz, emtricitabine, and tenofovir (Atripla). He had no other significant medical history, and the only medication he was currently taking was the trimethoprim-sulfamethoxazole.

On examination, his temperature was 38.7°C (101.7°F), blood pressure 109/68 mm Hg, heart rate 60 beats per minute, respiratory rate 18 breaths per minute, and oxygen saturation 100% while breathing supplemental oxygen via nasal cannula at 2 L/min. He did not appear seriously ill.

His mucous membranes were moist, and he did not have oral candidiasis. He had a palpable 1-cm nontender lymph node above his left clavicle. His heart and lungs were normal on physical examination. He had normal bowel sounds and no signs of peritonitis. His liver and spleen did not seem enlarged. Neurologic examination demonstrated normal cranial nerves, strength, reflexes, and sensation in all four limbs.

Initial blood tests (Table 1) showed a normal white blood cell count, normal results on a complete metabolic panel, and a lactate dehydrogenase level of 539 IU/L (reference range 313–618). His serum lactate level was within normal limits.

A chest radiograph showed multiple pulmonary nodules and a cavity in the lingula (Figure 1). In view of these findings, the patient was admitted to the hospital for further evaluation and testing.

HIV-specific tests performed on the second day of hospitalization showed extreme immunosuppression, with a CD4 count of 5 cells/μL (normal 326–1,404 cells/μL).

WHICH ORGANISM IS CAUSING HIS LUNG INFECTION?

1. Which of the following organisms is the least likely to be associated with this patient’s condition?

• Mycobacterium tuberculosis
• Pneumocystis jirovecii
• Coccidioides immitis
• Candida albicans
• Streptococcus pneumoniae
• Cytomegalovirus

Bacterial, fungal, and viral lung infections are common in HIV-infected patients, especially if they are not on antiretroviral therapy and their CD4 lymphocyte counts are low. Clues to the cause can be derived from the history, physical examination, and general laboratory studies. For instance, knowing where the patient lives and where he has travelled recently provides insight into exposure to endemic infectious agents.

The complete blood cell count with differential white blood cell count can help narrow the differential diagnosis but rarely helps exclude a possibility. Neutrophilia is common in bacterial infections. Lymphocytosis can be seen in tuberculosis, in fungal and viral infections, and, rarely, in hematologic malignancies. Eosinophilia can be seen in acute retroviral syndrome, fungal and helminthic infections, adrenal insufficiency, autoimmune disease, and lymphoma.

A caveat to these clues is that in severely immunocompromised hosts, like this man, diagnoses should not be excluded without firm evidence. This patient has severe, active immunosuppression, and only one of the six answer choices above is not a possible causative agent: C albicans rarely causes lung infection, even in immunocompromised people.

Mycobacterium tuberculosis

Tuberculosis can be the first manifestation of HIV infection. It can occur at any CD4 count, but as the count decreases, the risk of dissemination increases.¹ Classic symptoms are fever, night sweats, hemoptysis, and weight loss.

The CD4 count also affects the radiographic presentation. If the count is higher than 350 cells/μL, then infiltration of the upper lobe is likely; if it is lower than 200 cells/μL, then middle, lower, miliary, and extrapulmonary manifestations are likely.^1,2 Cavitation is less common in HIV-infected patients, but mediastinal adenopathy is more common.¹

Definitive diagnosis is via sputum examination, blood culture, nucleic acid amplification, or microscopic study of biopsy specimens of affected tissues to look for acid-fast bacilli.¹

Interferon-gamma-release assays such as the QuantiFERON test (Cellestis, Valencia, CA) or a tuberculin skin test can be used to check for latent tuberculosis infection. These tests can also provide evidence of active infection in the appropriate clinical context.³

Interferon-gamma-release assays have several advantages over skin testing: they are more sensitive (76% to 80%) and specific (97%); they do not give false-positive results in people who previously received bacille Calmette-Guérin vaccine; they react only minimally to previous exposure to nontuberculous mycobacteria; and interpretation is not subject to interreader variability.^4,5 However, concordance between skin testing and interferon-gamma-release assays is low. Therefore, either or both tests can be used if tuberculosis is strongly suspected, and a positive result on either test should prompt further workup.^6,7

Of note, both tests may be affected by immunosuppression, making both susceptible to false-negative results as the CD4 count declines.³

In any case, a positive acid-fast bacillus smear, radiographic evidence of latent infection, or pulmonary symptoms should be presumed to represent active tuberculosis. In such a situation, directly observed treatment with the typical four-drug regimen—rifampin (Rifadin), isoniazid, pyrazinamide, and ethambutol (Myambutol)—is recommended while awaiting definitive results from culture or polymerase chain reaction (PCR) testing.¹

 

 

Pneumocystis jirovecii

P jirovecii was previously known as P carinii, and P jirovecii pneumonia is an AIDS-defining illness. Most cases occur when the CD4 count falls below 200 cells/μL.¹ Symptoms, including a nonproductive cough, develop insidiously over days to weeks.

Physical examination may reveal inspiratory crackles; however, half of the time the physical examination is nondiagnostic. Oral candidiasis is a common coinfection. The lactate dehydrogenase level may be elevated.^1,8 Radiographs show bilateral interstitial infiltrates, and in 10% to 20% of patients lung cysts develop—hence the name of the organism.¹ Pneumothorax in a patient with HIV should prompt a workup for P jirovecii pneumonia.^9,10

No consensus exists for the diagnosis. However, if sputum examination is unrevealing but suspicion is high, then bronchoalveolar lavage can help.^11–13

Trimethoprim-sulfamethoxazole for 21 days is the first-line treatment, with glucocorticoids added if the Pao₂ is less than 70 mm Hg or if the alveolar-arterial oxygen gradient is greater than 35 mm Hg.¹

Coccidioides species

Coccidioides infection is typically due to either C immitis or C posadasii.¹⁴ People living in or travelling to areas where it is endemic, such as the southwestern United States, Mexico, and Central and South America, are at higher risk.¹⁴

Typical signs and symptoms of this fungal infection include an influenza-like illness with fever, cough, adenopathy, and wasting, and when combined with erythema nodosum, erythema multiforme, arthralgia, or ocular involvement, this constellation is colloquially termed “valley fever.”¹⁵ Most HIV-infected patients who have CD4 counts higher than 250 cells/μL present with focal pneumonia, while lower counts predispose to disseminated disease.^1,2,16

Findings on examination are nonspecific and depend on the various pulmonary manifestations, which include acute, chronic progressive, or diffuse pneumonia, nodules, or cavities.¹⁴ Eosinophilia may accompany the infection.¹⁵

The diagnosis can be made by finding the organisms on direct microscopic examination of involved tissues or secretions or on culture of clinical specimens.^1,2,14 Serologic tests, antigen detection tests, or culture can be helpful if positive, but negative results do not rule out the diagnosis.^1,2,14

A caveat about testing: if the pretest probability of infection is low, positive tests for immunoglobulin M (IgM) do not necessarily equal infection, and the IgM test should be followed up with confirmatory testing. Along the same lines, a high pretest probability should not be ignored if initial tests are negative, and patients in this situation should also undergo further evaluation.¹⁷

Therapy with an azole drug such as fluconazole (Diflucan) or one of the amphotericin B preparations should be started, depending on the severity of the disease.^1,2,14,18

Candida albicans

C albicans is a rare cause of lung infection.^19,20 It is, however, a common inhabitant of the upper airway tract, and pulmonary infection is usually the result of aspiration or hematogenous spread from either the gastrointestinal tract or an infected central venous catheter.²⁰

The presentation is relatively nonspecific. Fever despite broad-spectrum antibacterial therapy is a major clue. Radiographic abnormalities usually are due to other causes, such as superimposed infections or pulmonary hemorrhage.²¹ Sputum culture is unreliable because of colonization. The definitive diagnosis is based on lung biopsy demonstrating organisms within the tissue.^19,20,22

Therapy with a systemic antifungal agent is recommended.

Streptococcus pneumoniae

S pneumoniae is one of the most common bacterial causes of community-acquired pneumonia in people with or without HIV.^23–25 Moreover, two or more episodes of bacterial pneumonia in 12 months can be an AIDS-defining condition in patients with a positive serologic test for HIV.¹⁶ Therefore, in patients with fever, cough, and pulmonary infiltrates on chest radiography, S pneumoniae must always be considered.

Urinary antigen testing has a relatively high positive predictive value (> 89%) and specificity (96%) for diagnosing S pneumoniae pneumonia.²⁶ Blood and sputum cultures should be done not only to confirm the diagnosis, but also because the rates of bacteremia and drug resistance are higher with S pneumoniae infection in the HIV-infected.¹

A combination of a beta-lactam and a macrolide or respiratory fluoroquinolone is the treatment of choice.¹

Cytomegalovirus

Although influenza is the most common cause of viral pneumonia in HIV-infected people, cytomegalovirus is an opportunistic cause.² This is usually a reactivation of latent infection rather than new infection.²⁷ Typically, infections occur at CD4 counts lower than 50 cells/μL, with cough, dyspnea, and fever that last for 2 to 4 weeks.²

Crackles may be heard on lung examination. The lactate dehydrogenase level can be elevated, as in P jirovecii pneumonia.² Radiography can show a wide range of nonspecific findings, from reticular and ground-glass opacities to alveolar or interstitial infiltrates to nodules.

The diagnosis of cytomegalovirus pneumonia is not always clear. Since HIV-infected patients typically shed the virus in their airways, bronchoalveolar lavage is not adequate because a positive finding does not necessarily mean the patient has active viral pneumonitis.²⁷ For this reason, infection should be confirmed by biopsy demonstrating characteristic cytomegalovirus inclusions in lung tissue.²

Importantly, once cytomegalovirus pneumonia is confirmed, the patient should be screened for cytomegalovirus retinitis even if he or she has no visual symptoms, as cytomegalovirus pneumonitis is typically a part of a disseminated infection.¹

Treatment with intravenous ganciclovir (Cytovene) is required.¹

CASE CONTINUED: POSITIVE TESTS FOR COCCIDIOIDES

Our patient began empiric treatment for community-acquired pneumonia with intravenous ceftriaxone (Rocephin) and azithromycin (Zithromax).

He underwent computed tomography (CT) with contrast to further characterize the abnormal findings on chest radiography. This revealed a lingular cavitary airspace consolidation, 1- to 1.2-cm pulmonary nodules scattered throughout both lungs, and mediastinal lymphadenopathy (Figure 2).

On the basis of these findings, the patient was immediately placed in negative pressure respiratory isolation and underwent induced sputum examinations for tuberculosis. Further tests for S pneumoniae, S aureus, Mycoplasma, Legionella, influenza, Pneumocystis, Cryptococcus, Histoplasma, and Coccidioides species were performed.

QuantiFERON testing was negative, and blood cultures were sterile. The first induced sputum examination was negative for acid-fast bacilli. PCR testing for mycobacterial DNA in the sputum was also negative.

Both silver and direct fluorescent antibody staining of the sputum were negative for Pneumocystis. On the basis of these findings and the patient’s lack of clinical improvement with trimethoprim-sulfamethoxazole, Pneumocystis infection was excluded.

PCR testing of nasopharyngeal samples for influenza A and B was negative. Tests for S pneumoniae, S aureus, Mycoplasma, Legionella, influenza, Crypotococcus, and Histoplasma were also negative. However, sputum cytology revealed characteristic spherules consistent with coccidioidomycosis (Figure 3). The patient’s coccidioidal serologic tests with immunodiffusion and complement fixation returned negative, presumably because of his immunocompromised state. However, an enzymelinked immunoassay for urinary coccidioidal antigen (MiraVista Diagnostics, Indianapolis, IN), with a sensitivity of 71% and a specificity of 99%, was elevated at 5.15 ng/mL (reference range 0.07–2.0). Based on these findings and those on chest CT, the diagnosis of coccidioidomycosis was confirmed. Treatment needed to be started.

 

THE PATIENT BEGINS TREATMENT

2. Which treatment is most appropriate for this patient?

• Posaconazole (Noxafil)
• Caspofungin (Cancidas) and surgery
• Fluconazole
• Voriconazole (Vfend) and surgery
• Amphotericin B

Asymptomatic pulmonary coccidioidomycosis in an immunocompetent patient requires only supportive care. However, if the infection is symptomatic, severe (Table 2), or in an immunocompromised host, antifungal treatment is indicated.^1,18

Solitary pulmonary cavities tend to be asymptomatic and do not require treatment, even if coccidioidal infection is microbiologically confirmed.

However, if there is pain, hemoptysis, or bacterial superinfection, antifungal therapy may result in improvement but not closure of the cavity.¹⁸ Therefore, in all cases of symptomatic coccidioidal pulmonary cavities, surgical resection is the only definitive treatment.

Coccidioidal cavities may rupture and cause pyopneumothorax, but this is an infrequent complication, and antifungal therapy combined with surgical decortication is the treatment of choice.¹⁸

Commonly prescribed antifungals include fluconazole and amphotericin B, the latter usually reserved for patients with significant hypoxia or rapid clinical deterioration.¹⁸ At this time, there are not enough clinical data to show that voriconazole or posaconazole is effective, and thus neither is approved for the treatment of coccidioidomycosis. Likewise, there have been no human trials of the efficacy of caspofungin against Coccidioides infection, although it has been shown to be active in mouse models.¹⁸

Our patient was started on oral fluconazole and observed for clinical improvement or, conversely, for signs of dissemination. After 2 days, he had markedly improved, and within 1 week he was almost back to his baseline level of health. Testing for all other infectious etiologies was unrevealing, and he was removed from negative pressure isolation.

However, as we mentioned above, his CD4 count was 5 cells/μL. We discussed the issue with the patient, and he said he was willing to comply with his treatment for both his Coccidioides and his HIV infection. After much deliberation, he said he was also willing to start and comply with prophylactic treatment for opportunistic infections.

PREVENTING OPPORTUNISTIC INFECTIONS IN HIV PATIENTS

3. Which of the following prophylactic regimens is most appropriate for this patient?

• Trimethoprim-sulfamethoxazole, atovaquone (Mepron), and azithromycin
• Trimethoprim-sulfamethoxazole and azithromycin
• Pentamidine (Nebupent), dapsone, and clarithromycin (Biaxin)
• Dapsone and clarithromycin
• Trimethoprim-sulfamethoxazole by itself

According to guidelines for the prevention of opportunistic diseases in patients with HIV, he needs primary prophylaxis against the following organisms: P jirovecii, Toxoplasma gondii, and Mycobacterium avium complex.¹

The CD4 count dictates the appropriate time to start therapy. If the count is lower than 200 cells/μL or if the patient has oropharyngeal candidiasis regardless of the CD4 count, trimethoprim-sulfamethoxazole is indicated to prevent P jirovecii pneumonia. In those who cannot tolerate trimethoprim-sulfamethoxazole or who are allergic to it, dapsone, pentamidine, or atovaquone can be substituted.¹

In patients seropositive for T gondii, a CD4 count lower than 100/μL indicates the need for prophylaxis.¹ Prophylactic measures are similar to those for Pneumocystis. However, if the patient cannot tolerate trimethoprim-sulfamethoxazole, the recommended alternative is dapsone-pyrimethamine with leucovorin, which is also effective against Pneumocystis.¹

Finally, if the CD4 count is lower than 50 cells/μL, prophylaxis against M avium complex is mandatory, with either azithromycin weekly or clarithromycin daily.¹

Given our patient’s degree of immunosuppression, trimethoprim-sulfamethoxazole plus azithromycin is his most appropriate option.

Trimethoprim-sulfamethoxazole and azithromycin were added to his antimicrobial regimen before he was discharged. Two weeks later, he noted no side effects from any of the medications, he had no new symptoms, he was feeling well, and his cough had improved greatly. He did not have any signs of dissemination of his coccidioidal infection, and we concluded that the primary and only infection was located in the lungs.

DISSEMINATED COCCIDIOIDOMYCOSIS

4. Which of the following extrapulmonary sites is Coccidioides least likely to infect?

• Brain
• Skin
• Meninges
• Lymph nodes
• Bones
• Joints

Extrapulmonary coccidioidomycosis can involve almost any site. However, the most common sites of dissemination are the skin, lymph nodes, bones, and joints.¹⁴ The least likely site is the brain.

Central nervous system involvement

In the central nervous system, involvement is typically with the meninges, rather than frank involvement of the brain parenchyma.^18,28,29 Although patients with HIV or those who are otherwise severely immunocompromised are at higher risk for coccidioidal meningitis, it is rare even in this population.^30,31 Meningitis most commonly presents as headache, vomiting, meningismus, confusion, or diplopia.^32,33

If neurologic findings are absent, experts do not generally recommend lumbar puncture because the incidence of meningeal involvement is low. When cerebrospinal fluid is obtained in an active case of coccidioidal meningitis, fluid analysis typically finds elevated protein, low glucose, and lymphocytic pleocytosis.^1,32

Meningeal enhancement on CT or magnetic resonance imaging is common.³⁴ The diagnosis is established by culture or serologic testing of cerebrospinal fluid (IgM titer, IgG titer, immunodiffusion, or complement fixation).¹⁴

Of note, cerebral infarction and hydrocephalus are feared complications and pose a serious risk of death in any patient.^32,35 In these cases, treatment with antifungals is lifelong, regardless of immune system status.¹⁸

Skin involvement

Skin involvement is variable, consisting of nodules, verrucae, abscesses, or ulcerations.^15,16 Hemorrhage from the skin is relatively common.³⁶ From the skin, the infection can spread to the lymph nodes, leading to regional lymphadenopathy.^14,15 Nodes can ulcerate, drain, or even become necrotic.

Bone and joint involvement

Once integrity of the blood vessels is disrupted, Coccidioides can spread via the blood to the bones or joints,^14,15 causing osteomyelitis, septic arthritis, or synovitis. Subcutaneous abscesses or sinus tracts may subsequently develop.^14,15

 

HOW LONG MUST HE BE TREATED?

On follow-up, the patient asked how long he needed to continue his antifungal regimen and if any other testing for his coccidioidal infection was necessary, since he was feeling better.

5. Which is the most appropriate response to the patient’s question?

• He can discontinue his antifungal drugs; no further testing is necessary
• He needs 14 more days of antifungal therapy and periodic serologic tests
• He needs 2.5 more months of antifungal therapy and monthly blood cultures
• He needs lifelong antifungal therapy and periodic urinary antigen levels
• He needs 5.5 more months of antifungal therapy; bronchoscopy with bronchoalveolar lavage at 1 year

How long to treat and how to monitor for coccidioidomycosis vary by patient.

Duration of therapy depends on symptoms and immune status

The severity of infection (Table 2) and the immune status are important factors that must be considered when tailoring a therapeutic regimen.

Immunocompetent patients without symptoms or with mild symptoms usually do not need therapy and are followed periodically for signs of improvement.^14,18,29

Immunocompetent patients with severe symptoms typically receive 3 to 6 months of antifungal therapy.¹⁸

Immunocompromised patients (especially HIV-infected patients with CD4 counts < 250 cells/μL) need antifungal treatment, regardless of the severity of infection.^14,18,29 In many cases, the type of infection will dictate the duration of therapy.

Diffuse pneumonia or extrapulmonary dissemination typically requires treatment for at least 1 year regardless of immune status.^14,18 For those with HIV and diffuse pneumonia, dissemination, or meningitis, guidelines dictate that secondary prophylaxis be started after at least 1 year of therapy and improvement in clinical status; it should be continued indefinitely to prevent reactivation of latent infection.¹⁸

The guidelines say that in patients with higher CD4 counts (presumably > 250 cells/μL) and nonmeningeal coccidioidomycosis, providers may consider discontinuing secondary prophylaxis, as long as there is clinical evidence of improvement and control of the primary infection.¹⁸ However, many experts advocate continuing secondary prophylaxis regardless of the CD4 count, as the rates of relapse and dissemination are high.^1,16,37

Monitoring

Regardless of the therapy chosen, disease monitoring every 2 to 4 months with clinical history and examination, radiography, and coccidioidal-specific testing is recommended for at least 1 year, and perhaps longer, to ensure complete resolution and to monitor for signs of dissemination.^14,18

Which test to use is not clear. Serologic testing identifies antibodies (IgM or IgG) to coccidioidal antigens. IgM appears during the acute infection, and tests include immunodiffusion, latex agglutination, and enzymelinked immunoassays. The last two are highly sensitive but have a significant false-positive rate, and should be confirmed with the former if found to be positive.^17,18 IgG appears weeks after the acute infection and can be evaluated with immunodiffusion or enzyme-linked immunoassay as well.

Keep in mind that these tests provide only qualitative results on the presence of these antibodies, not quantitative information. Furthermore, enzyme-linked immunoassay is not as accurate as immunodiffusion, which has a sensitivity in immunocompromised patients of only approximately 50%.^38,39

For that reason, complement fixation titers are extremely helpful because they reflect the severity of infection, can be used to monitor the response to treatment, and can even provide insight into the prognosis.¹⁸ The sensitivity of this test in immunocompromised hosts is 60% to 70%.³⁸ Titers can be checked to confirm the diagnosis and can be periodically monitored throughout the treatment course to ensure efficacy of therapy and to watch for reactivation of the infection.¹ In fact, an initial complement fixation titer of 1:2 or 1:4 is associated with favorable outcomes, while a titer greater than 1:16 portends dissemination.¹⁸

The caveat to any serologic test (immunodiffusion, enzyme-linked immunoassay, and complement fixation) is that severely immunocompromised patients (as in our case) may not mount an immune response and may have falsely low titers even in the face of a severe infection, and therefore these tests may not be reliable.³⁸ In these situations, urinary coccidioidal antigen detection assay (sensitivity 71%) or nucleic acid amplification of coccidioidal DNA (sensitivity 75%) may be of more help.^40,41

Therefore, in the setting of HIV infection, an asymptomatic pulmonary cavity, and diffuse pulmonary involvement secondary to coccidioidal infection, lifelong antibiotics (treatment plus secondary prophylaxis) with periodic testing of urinary coccidioidal antigen levels is the best response to the patient’s question, given that his complement fixation titers were initially negative and antigen levels were positive.

CASE CONCLUDED

The patient continues to be followed for his HIV infection. He is undergoing serologic and urinary antigen testing for Coccidioides infection every 3 months in addition to his maintenance HIV testing. He is on chronic suppressive therapy with fluconazole. He has not had a recurrence of his Coccidioides infection, nor have there been any signs of dissemination.

CAVITARY LUNG LESIONS IN HIV PATIENTS

In patients with HIV, cavitary lung lesions on chest radiography can be due to a wide variety of etiologies that range from infection to malignancy. Historical clues, including environmental exposure, occupation, geographic residence, sick contacts, travel, or animal contact can be helpful in ordering subsequent confirmatory testing, especially in the case of infection.

Tuberculosis should be suspected, and appropriate isolation precautions should be taken until it is ruled out.

Laboratory testing, including the complete blood cell count with differential and CD4 count, provide ancillary data to narrow the differential diagnosis. For example, if the CD4 count is greater than 200 cells/μL, mycobacterial infection should be strongly suspected; however, lower CD4 counts should also prompt a search for opportunistic infections. In the appropriate clinical scenario, malignancies including Kaposi sarcoma, non-Hodgkin lymphoma, and bronchogenic carcinoma can be seen and should also be considered.

Nevertheless, the evaluation hinges on the sputum examination and CT scan of the chest to further characterize the cavity, surrounding lung parenchyma, lymph nodes, and potential fluid collections. Usually, further serologic tests and even bronchoscopy with bronchoalveolar lavage and transbronchial biopsy are required. Treatment should begin once the most likely diagnosis is established.

Coccidioidal pneumonia should be considered in all patients with immunodeficiency, including HIV patients, transplant recipients, those undergoing chemotherapy, and those with intrinsic immune system defects, especially if they have a history of exposure or if they are from an endemic region. Antifungal therapy should be initiated early, and dissemination must be ruled out. Suppressive therapy is mandatory for those with a severely compromised immune system, and serologic testing to ensure remission of the infection is needed. Patients who were previously exposed to Coccidioides or who vacationed or live in the southwestern United States (where it is prevalent) are at risk and may present with any number of symptoms.

A 37-year-old man presented to the emergency department with an 8-week history of a mildly productive cough and shortness of breath accompanied by high fevers, chills, and night sweats. He also had some nausea but no vomiting.

Four days earlier, he had been evaluated by his primary care physician, who prescribed a 14-day course of one double-strength trimethoprim-sulfamethoxazole tablet (Bactrim DS) every 12 hours for presumed acute bronchitis, but his symptoms did not improve.

He was unemployed, living in Arizona, married with children. He denied any use of tobacco, alcohol, or injection drugs. On further questioning, he disclosed that he had unintentionally lost 30 pounds over the past 2 to 3 months and had been feeling tired.

When asked about his medical history, he revealed that he had been diagnosed with human immunodeficiency virus (HIV) infection in 2008 and that recently he had not been taking his antiretroviral medication, a once-daily combination pill containing efavirenz, emtricitabine, and tenofovir (Atripla). He had no other significant medical history, and the only medication he was currently taking was the trimethoprim-sulfamethoxazole.

On examination, his temperature was 38.7°C (101.7°F), blood pressure 109/68 mm Hg, heart rate 60 beats per minute, respiratory rate 18 breaths per minute, and oxygen saturation 100% while breathing supplemental oxygen via nasal cannula at 2 L/min. He did not appear seriously ill.

His mucous membranes were moist, and he did not have oral candidiasis. He had a palpable 1-cm nontender lymph node above his left clavicle. His heart and lungs were normal on physical examination. He had normal bowel sounds and no signs of peritonitis. His liver and spleen did not seem enlarged. Neurologic examination demonstrated normal cranial nerves, strength, reflexes, and sensation in all four limbs.

Initial blood tests (Table 1) showed a normal white blood cell count, normal results on a complete metabolic panel, and a lactate dehydrogenase level of 539 IU/L (reference range 313–618). His serum lactate level was within normal limits.

A chest radiograph showed multiple pulmonary nodules and a cavity in the lingula (Figure 1). In view of these findings, the patient was admitted to the hospital for further evaluation and testing.

HIV-specific tests performed on the second day of hospitalization showed extreme immunosuppression, with a CD4 count of 5 cells/μL (normal 326–1,404 cells/μL).

WHICH ORGANISM IS CAUSING HIS LUNG INFECTION?

1. Which of the following organisms is the least likely to be associated with this patient’s condition?

• Mycobacterium tuberculosis
• Pneumocystis jirovecii
• Coccidioides immitis
• Candida albicans
• Streptococcus pneumoniae
• Cytomegalovirus

Bacterial, fungal, and viral lung infections are common in HIV-infected patients, especially if they are not on antiretroviral therapy and their CD4 lymphocyte counts are low. Clues to the cause can be derived from the history, physical examination, and general laboratory studies. For instance, knowing where the patient lives and where he has travelled recently provides insight into exposure to endemic infectious agents.

The complete blood cell count with differential white blood cell count can help narrow the differential diagnosis but rarely helps exclude a possibility. Neutrophilia is common in bacterial infections. Lymphocytosis can be seen in tuberculosis, in fungal and viral infections, and, rarely, in hematologic malignancies. Eosinophilia can be seen in acute retroviral syndrome, fungal and helminthic infections, adrenal insufficiency, autoimmune disease, and lymphoma.

A caveat to these clues is that in severely immunocompromised hosts, like this man, diagnoses should not be excluded without firm evidence. This patient has severe, active immunosuppression, and only one of the six answer choices above is not a possible causative agent: C albicans rarely causes lung infection, even in immunocompromised people.

Mycobacterium tuberculosis

Tuberculosis can be the first manifestation of HIV infection. It can occur at any CD4 count, but as the count decreases, the risk of dissemination increases.¹ Classic symptoms are fever, night sweats, hemoptysis, and weight loss.

The CD4 count also affects the radiographic presentation. If the count is higher than 350 cells/μL, then infiltration of the upper lobe is likely; if it is lower than 200 cells/μL, then middle, lower, miliary, and extrapulmonary manifestations are likely.^1,2 Cavitation is less common in HIV-infected patients, but mediastinal adenopathy is more common.¹

Definitive diagnosis is via sputum examination, blood culture, nucleic acid amplification, or microscopic study of biopsy specimens of affected tissues to look for acid-fast bacilli.¹

Interferon-gamma-release assays such as the QuantiFERON test (Cellestis, Valencia, CA) or a tuberculin skin test can be used to check for latent tuberculosis infection. These tests can also provide evidence of active infection in the appropriate clinical context.³

Interferon-gamma-release assays have several advantages over skin testing: they are more sensitive (76% to 80%) and specific (97%); they do not give false-positive results in people who previously received bacille Calmette-Guérin vaccine; they react only minimally to previous exposure to nontuberculous mycobacteria; and interpretation is not subject to interreader variability.^4,5 However, concordance between skin testing and interferon-gamma-release assays is low. Therefore, either or both tests can be used if tuberculosis is strongly suspected, and a positive result on either test should prompt further workup.^6,7

Of note, both tests may be affected by immunosuppression, making both susceptible to false-negative results as the CD4 count declines.³

In any case, a positive acid-fast bacillus smear, radiographic evidence of latent infection, or pulmonary symptoms should be presumed to represent active tuberculosis. In such a situation, directly observed treatment with the typical four-drug regimen—rifampin (Rifadin), isoniazid, pyrazinamide, and ethambutol (Myambutol)—is recommended while awaiting definitive results from culture or polymerase chain reaction (PCR) testing.¹

 

 

Pneumocystis jirovecii

P jirovecii was previously known as P carinii, and P jirovecii pneumonia is an AIDS-defining illness. Most cases occur when the CD4 count falls below 200 cells/μL.¹ Symptoms, including a nonproductive cough, develop insidiously over days to weeks.

Physical examination may reveal inspiratory crackles; however, half of the time the physical examination is nondiagnostic. Oral candidiasis is a common coinfection. The lactate dehydrogenase level may be elevated.^1,8 Radiographs show bilateral interstitial infiltrates, and in 10% to 20% of patients lung cysts develop—hence the name of the organism.¹ Pneumothorax in a patient with HIV should prompt a workup for P jirovecii pneumonia.^9,10

No consensus exists for the diagnosis. However, if sputum examination is unrevealing but suspicion is high, then bronchoalveolar lavage can help.^11–13

Trimethoprim-sulfamethoxazole for 21 days is the first-line treatment, with glucocorticoids added if the Pao₂ is less than 70 mm Hg or if the alveolar-arterial oxygen gradient is greater than 35 mm Hg.¹

Coccidioides species

Coccidioides infection is typically due to either C immitis or C posadasii.¹⁴ People living in or travelling to areas where it is endemic, such as the southwestern United States, Mexico, and Central and South America, are at higher risk.¹⁴

Typical signs and symptoms of this fungal infection include an influenza-like illness with fever, cough, adenopathy, and wasting, and when combined with erythema nodosum, erythema multiforme, arthralgia, or ocular involvement, this constellation is colloquially termed “valley fever.”¹⁵ Most HIV-infected patients who have CD4 counts higher than 250 cells/μL present with focal pneumonia, while lower counts predispose to disseminated disease.^1,2,16

Findings on examination are nonspecific and depend on the various pulmonary manifestations, which include acute, chronic progressive, or diffuse pneumonia, nodules, or cavities.¹⁴ Eosinophilia may accompany the infection.¹⁵

The diagnosis can be made by finding the organisms on direct microscopic examination of involved tissues or secretions or on culture of clinical specimens.^1,2,14 Serologic tests, antigen detection tests, or culture can be helpful if positive, but negative results do not rule out the diagnosis.^1,2,14

A caveat about testing: if the pretest probability of infection is low, positive tests for immunoglobulin M (IgM) do not necessarily equal infection, and the IgM test should be followed up with confirmatory testing. Along the same lines, a high pretest probability should not be ignored if initial tests are negative, and patients in this situation should also undergo further evaluation.¹⁷

Therapy with an azole drug such as fluconazole (Diflucan) or one of the amphotericin B preparations should be started, depending on the severity of the disease.^1,2,14,18

Candida albicans

C albicans is a rare cause of lung infection.^19,20 It is, however, a common inhabitant of the upper airway tract, and pulmonary infection is usually the result of aspiration or hematogenous spread from either the gastrointestinal tract or an infected central venous catheter.²⁰

The presentation is relatively nonspecific. Fever despite broad-spectrum antibacterial therapy is a major clue. Radiographic abnormalities usually are due to other causes, such as superimposed infections or pulmonary hemorrhage.²¹ Sputum culture is unreliable because of colonization. The definitive diagnosis is based on lung biopsy demonstrating organisms within the tissue.^19,20,22

Therapy with a systemic antifungal agent is recommended.

Streptococcus pneumoniae

S pneumoniae is one of the most common bacterial causes of community-acquired pneumonia in people with or without HIV.^23–25 Moreover, two or more episodes of bacterial pneumonia in 12 months can be an AIDS-defining condition in patients with a positive serologic test for HIV.¹⁶ Therefore, in patients with fever, cough, and pulmonary infiltrates on chest radiography, S pneumoniae must always be considered.

Urinary antigen testing has a relatively high positive predictive value (> 89%) and specificity (96%) for diagnosing S pneumoniae pneumonia.²⁶ Blood and sputum cultures should be done not only to confirm the diagnosis, but also because the rates of bacteremia and drug resistance are higher with S pneumoniae infection in the HIV-infected.¹

A combination of a beta-lactam and a macrolide or respiratory fluoroquinolone is the treatment of choice.¹

Cytomegalovirus

Although influenza is the most common cause of viral pneumonia in HIV-infected people, cytomegalovirus is an opportunistic cause.² This is usually a reactivation of latent infection rather than new infection.²⁷ Typically, infections occur at CD4 counts lower than 50 cells/μL, with cough, dyspnea, and fever that last for 2 to 4 weeks.²

Crackles may be heard on lung examination. The lactate dehydrogenase level can be elevated, as in P jirovecii pneumonia.² Radiography can show a wide range of nonspecific findings, from reticular and ground-glass opacities to alveolar or interstitial infiltrates to nodules.

The diagnosis of cytomegalovirus pneumonia is not always clear. Since HIV-infected patients typically shed the virus in their airways, bronchoalveolar lavage is not adequate because a positive finding does not necessarily mean the patient has active viral pneumonitis.²⁷ For this reason, infection should be confirmed by biopsy demonstrating characteristic cytomegalovirus inclusions in lung tissue.²

Importantly, once cytomegalovirus pneumonia is confirmed, the patient should be screened for cytomegalovirus retinitis even if he or she has no visual symptoms, as cytomegalovirus pneumonitis is typically a part of a disseminated infection.¹

Treatment with intravenous ganciclovir (Cytovene) is required.¹

CASE CONTINUED: POSITIVE TESTS FOR COCCIDIOIDES

Our patient began empiric treatment for community-acquired pneumonia with intravenous ceftriaxone (Rocephin) and azithromycin (Zithromax).

He underwent computed tomography (CT) with contrast to further characterize the abnormal findings on chest radiography. This revealed a lingular cavitary airspace consolidation, 1- to 1.2-cm pulmonary nodules scattered throughout both lungs, and mediastinal lymphadenopathy (Figure 2).

On the basis of these findings, the patient was immediately placed in negative pressure respiratory isolation and underwent induced sputum examinations for tuberculosis. Further tests for S pneumoniae, S aureus, Mycoplasma, Legionella, influenza, Pneumocystis, Cryptococcus, Histoplasma, and Coccidioides species were performed.

QuantiFERON testing was negative, and blood cultures were sterile. The first induced sputum examination was negative for acid-fast bacilli. PCR testing for mycobacterial DNA in the sputum was also negative.

Both silver and direct fluorescent antibody staining of the sputum were negative for Pneumocystis. On the basis of these findings and the patient’s lack of clinical improvement with trimethoprim-sulfamethoxazole, Pneumocystis infection was excluded.

PCR testing of nasopharyngeal samples for influenza A and B was negative. Tests for S pneumoniae, S aureus, Mycoplasma, Legionella, influenza, Crypotococcus, and Histoplasma were also negative. However, sputum cytology revealed characteristic spherules consistent with coccidioidomycosis (Figure 3). The patient’s coccidioidal serologic tests with immunodiffusion and complement fixation returned negative, presumably because of his immunocompromised state. However, an enzymelinked immunoassay for urinary coccidioidal antigen (MiraVista Diagnostics, Indianapolis, IN), with a sensitivity of 71% and a specificity of 99%, was elevated at 5.15 ng/mL (reference range 0.07–2.0). Based on these findings and those on chest CT, the diagnosis of coccidioidomycosis was confirmed. Treatment needed to be started.

 

THE PATIENT BEGINS TREATMENT

2. Which treatment is most appropriate for this patient?

• Posaconazole (Noxafil)
• Caspofungin (Cancidas) and surgery
• Fluconazole
• Voriconazole (Vfend) and surgery
• Amphotericin B

Asymptomatic pulmonary coccidioidomycosis in an immunocompetent patient requires only supportive care. However, if the infection is symptomatic, severe (Table 2), or in an immunocompromised host, antifungal treatment is indicated.^1,18

Solitary pulmonary cavities tend to be asymptomatic and do not require treatment, even if coccidioidal infection is microbiologically confirmed.

However, if there is pain, hemoptysis, or bacterial superinfection, antifungal therapy may result in improvement but not closure of the cavity.¹⁸ Therefore, in all cases of symptomatic coccidioidal pulmonary cavities, surgical resection is the only definitive treatment.

Coccidioidal cavities may rupture and cause pyopneumothorax, but this is an infrequent complication, and antifungal therapy combined with surgical decortication is the treatment of choice.¹⁸

Commonly prescribed antifungals include fluconazole and amphotericin B, the latter usually reserved for patients with significant hypoxia or rapid clinical deterioration.¹⁸ At this time, there are not enough clinical data to show that voriconazole or posaconazole is effective, and thus neither is approved for the treatment of coccidioidomycosis. Likewise, there have been no human trials of the efficacy of caspofungin against Coccidioides infection, although it has been shown to be active in mouse models.¹⁸

Our patient was started on oral fluconazole and observed for clinical improvement or, conversely, for signs of dissemination. After 2 days, he had markedly improved, and within 1 week he was almost back to his baseline level of health. Testing for all other infectious etiologies was unrevealing, and he was removed from negative pressure isolation.

However, as we mentioned above, his CD4 count was 5 cells/μL. We discussed the issue with the patient, and he said he was willing to comply with his treatment for both his Coccidioides and his HIV infection. After much deliberation, he said he was also willing to start and comply with prophylactic treatment for opportunistic infections.

PREVENTING OPPORTUNISTIC INFECTIONS IN HIV PATIENTS

3. Which of the following prophylactic regimens is most appropriate for this patient?

• Trimethoprim-sulfamethoxazole, atovaquone (Mepron), and azithromycin
• Trimethoprim-sulfamethoxazole and azithromycin
• Pentamidine (Nebupent), dapsone, and clarithromycin (Biaxin)
• Dapsone and clarithromycin
• Trimethoprim-sulfamethoxazole by itself

According to guidelines for the prevention of opportunistic diseases in patients with HIV, he needs primary prophylaxis against the following organisms: P jirovecii, Toxoplasma gondii, and Mycobacterium avium complex.¹

The CD4 count dictates the appropriate time to start therapy. If the count is lower than 200 cells/μL or if the patient has oropharyngeal candidiasis regardless of the CD4 count, trimethoprim-sulfamethoxazole is indicated to prevent P jirovecii pneumonia. In those who cannot tolerate trimethoprim-sulfamethoxazole or who are allergic to it, dapsone, pentamidine, or atovaquone can be substituted.¹

In patients seropositive for T gondii, a CD4 count lower than 100/μL indicates the need for prophylaxis.¹ Prophylactic measures are similar to those for Pneumocystis. However, if the patient cannot tolerate trimethoprim-sulfamethoxazole, the recommended alternative is dapsone-pyrimethamine with leucovorin, which is also effective against Pneumocystis.¹

Finally, if the CD4 count is lower than 50 cells/μL, prophylaxis against M avium complex is mandatory, with either azithromycin weekly or clarithromycin daily.¹

Given our patient’s degree of immunosuppression, trimethoprim-sulfamethoxazole plus azithromycin is his most appropriate option.

Trimethoprim-sulfamethoxazole and azithromycin were added to his antimicrobial regimen before he was discharged. Two weeks later, he noted no side effects from any of the medications, he had no new symptoms, he was feeling well, and his cough had improved greatly. He did not have any signs of dissemination of his coccidioidal infection, and we concluded that the primary and only infection was located in the lungs.

DISSEMINATED COCCIDIOIDOMYCOSIS

4. Which of the following extrapulmonary sites is Coccidioides least likely to infect?

• Brain
• Skin
• Meninges
• Lymph nodes
• Bones
• Joints

Extrapulmonary coccidioidomycosis can involve almost any site. However, the most common sites of dissemination are the skin, lymph nodes, bones, and joints.¹⁴ The least likely site is the brain.

Central nervous system involvement

In the central nervous system, involvement is typically with the meninges, rather than frank involvement of the brain parenchyma.^18,28,29 Although patients with HIV or those who are otherwise severely immunocompromised are at higher risk for coccidioidal meningitis, it is rare even in this population.^30,31 Meningitis most commonly presents as headache, vomiting, meningismus, confusion, or diplopia.^32,33

If neurologic findings are absent, experts do not generally recommend lumbar puncture because the incidence of meningeal involvement is low. When cerebrospinal fluid is obtained in an active case of coccidioidal meningitis, fluid analysis typically finds elevated protein, low glucose, and lymphocytic pleocytosis.^1,32

Meningeal enhancement on CT or magnetic resonance imaging is common.³⁴ The diagnosis is established by culture or serologic testing of cerebrospinal fluid (IgM titer, IgG titer, immunodiffusion, or complement fixation).¹⁴

Of note, cerebral infarction and hydrocephalus are feared complications and pose a serious risk of death in any patient.^32,35 In these cases, treatment with antifungals is lifelong, regardless of immune system status.¹⁸

Skin involvement

Skin involvement is variable, consisting of nodules, verrucae, abscesses, or ulcerations.^15,16 Hemorrhage from the skin is relatively common.³⁶ From the skin, the infection can spread to the lymph nodes, leading to regional lymphadenopathy.^14,15 Nodes can ulcerate, drain, or even become necrotic.

Bone and joint involvement

Once integrity of the blood vessels is disrupted, Coccidioides can spread via the blood to the bones or joints,^14,15 causing osteomyelitis, septic arthritis, or synovitis. Subcutaneous abscesses or sinus tracts may subsequently develop.^14,15

 

HOW LONG MUST HE BE TREATED?

On follow-up, the patient asked how long he needed to continue his antifungal regimen and if any other testing for his coccidioidal infection was necessary, since he was feeling better.

5. Which is the most appropriate response to the patient’s question?

• He can discontinue his antifungal drugs; no further testing is necessary
• He needs 14 more days of antifungal therapy and periodic serologic tests
• He needs 2.5 more months of antifungal therapy and monthly blood cultures
• He needs lifelong antifungal therapy and periodic urinary antigen levels
• He needs 5.5 more months of antifungal therapy; bronchoscopy with bronchoalveolar lavage at 1 year

How long to treat and how to monitor for coccidioidomycosis vary by patient.

Duration of therapy depends on symptoms and immune status

The severity of infection (Table 2) and the immune status are important factors that must be considered when tailoring a therapeutic regimen.

Immunocompetent patients without symptoms or with mild symptoms usually do not need therapy and are followed periodically for signs of improvement.^14,18,29

Immunocompetent patients with severe symptoms typically receive 3 to 6 months of antifungal therapy.¹⁸

Immunocompromised patients (especially HIV-infected patients with CD4 counts < 250 cells/μL) need antifungal treatment, regardless of the severity of infection.^14,18,29 In many cases, the type of infection will dictate the duration of therapy.

Diffuse pneumonia or extrapulmonary dissemination typically requires treatment for at least 1 year regardless of immune status.^14,18 For those with HIV and diffuse pneumonia, dissemination, or meningitis, guidelines dictate that secondary prophylaxis be started after at least 1 year of therapy and improvement in clinical status; it should be continued indefinitely to prevent reactivation of latent infection.¹⁸

The guidelines say that in patients with higher CD4 counts (presumably > 250 cells/μL) and nonmeningeal coccidioidomycosis, providers may consider discontinuing secondary prophylaxis, as long as there is clinical evidence of improvement and control of the primary infection.¹⁸ However, many experts advocate continuing secondary prophylaxis regardless of the CD4 count, as the rates of relapse and dissemination are high.^1,16,37

Monitoring

Regardless of the therapy chosen, disease monitoring every 2 to 4 months with clinical history and examination, radiography, and coccidioidal-specific testing is recommended for at least 1 year, and perhaps longer, to ensure complete resolution and to monitor for signs of dissemination.^14,18

Which test to use is not clear. Serologic testing identifies antibodies (IgM or IgG) to coccidioidal antigens. IgM appears during the acute infection, and tests include immunodiffusion, latex agglutination, and enzymelinked immunoassays. The last two are highly sensitive but have a significant false-positive rate, and should be confirmed with the former if found to be positive.^17,18 IgG appears weeks after the acute infection and can be evaluated with immunodiffusion or enzyme-linked immunoassay as well.

Keep in mind that these tests provide only qualitative results on the presence of these antibodies, not quantitative information. Furthermore, enzyme-linked immunoassay is not as accurate as immunodiffusion, which has a sensitivity in immunocompromised patients of only approximately 50%.^38,39

For that reason, complement fixation titers are extremely helpful because they reflect the severity of infection, can be used to monitor the response to treatment, and can even provide insight into the prognosis.¹⁸ The sensitivity of this test in immunocompromised hosts is 60% to 70%.³⁸ Titers can be checked to confirm the diagnosis and can be periodically monitored throughout the treatment course to ensure efficacy of therapy and to watch for reactivation of the infection.¹ In fact, an initial complement fixation titer of 1:2 or 1:4 is associated with favorable outcomes, while a titer greater than 1:16 portends dissemination.¹⁸

The caveat to any serologic test (immunodiffusion, enzyme-linked immunoassay, and complement fixation) is that severely immunocompromised patients (as in our case) may not mount an immune response and may have falsely low titers even in the face of a severe infection, and therefore these tests may not be reliable.³⁸ In these situations, urinary coccidioidal antigen detection assay (sensitivity 71%) or nucleic acid amplification of coccidioidal DNA (sensitivity 75%) may be of more help.^40,41

Therefore, in the setting of HIV infection, an asymptomatic pulmonary cavity, and diffuse pulmonary involvement secondary to coccidioidal infection, lifelong antibiotics (treatment plus secondary prophylaxis) with periodic testing of urinary coccidioidal antigen levels is the best response to the patient’s question, given that his complement fixation titers were initially negative and antigen levels were positive.

CASE CONCLUDED

The patient continues to be followed for his HIV infection. He is undergoing serologic and urinary antigen testing for Coccidioides infection every 3 months in addition to his maintenance HIV testing. He is on chronic suppressive therapy with fluconazole. He has not had a recurrence of his Coccidioides infection, nor have there been any signs of dissemination.

CAVITARY LUNG LESIONS IN HIV PATIENTS

In patients with HIV, cavitary lung lesions on chest radiography can be due to a wide variety of etiologies that range from infection to malignancy. Historical clues, including environmental exposure, occupation, geographic residence, sick contacts, travel, or animal contact can be helpful in ordering subsequent confirmatory testing, especially in the case of infection.

Tuberculosis should be suspected, and appropriate isolation precautions should be taken until it is ruled out.

Laboratory testing, including the complete blood cell count with differential and CD4 count, provide ancillary data to narrow the differential diagnosis. For example, if the CD4 count is greater than 200 cells/μL, mycobacterial infection should be strongly suspected; however, lower CD4 counts should also prompt a search for opportunistic infections. In the appropriate clinical scenario, malignancies including Kaposi sarcoma, non-Hodgkin lymphoma, and bronchogenic carcinoma can be seen and should also be considered.

Nevertheless, the evaluation hinges on the sputum examination and CT scan of the chest to further characterize the cavity, surrounding lung parenchyma, lymph nodes, and potential fluid collections. Usually, further serologic tests and even bronchoscopy with bronchoalveolar lavage and transbronchial biopsy are required. Treatment should begin once the most likely diagnosis is established.

Coccidioidal pneumonia should be considered in all patients with immunodeficiency, including HIV patients, transplant recipients, those undergoing chemotherapy, and those with intrinsic immune system defects, especially if they have a history of exposure or if they are from an endemic region. Antifungal therapy should be initiated early, and dissemination must be ruled out. Suppressive therapy is mandatory for those with a severely compromised immune system, and serologic testing to ensure remission of the infection is needed. Patients who were previously exposed to Coccidioides or who vacationed or live in the southwestern United States (where it is prevalent) are at risk and may present with any number of symptoms.

A 54-year-old woman with a 1-month history of progressive weakness was transported to the emergency department of a local hospital when a family member found her unresponsive. Before this event, the patient had said she had been feeling tired and cold and looking pale for several weeks.

In the emergency department, her temperature was low. Cableomputed tomography (CT) of the head showed a 1.4-cm hyperdense extraaxial mass. Imaging of the chest showed focal consolidations within the anterior segment of the right upper lobe and the left and right lower lobes.

A urine toxicology screen was positive for acetaminophen (Tylenol), opiates, and benzodiazepines. She was given three doses of naloxone (Narcan), which raised her level of arousal; however, she later became obtunded again and was intubated and transferred to Cleveland Clinic.

A new CT scan of the head confirmed a small left temporal, extradural, calcified lesion with no mass effect or overt bleeding; it appeared most compatible with a solitary calcified meningioma—a likely benign finding.

Her medical history includes hypertension, type 2 diabetes (controlled with diet), and osteoarthritis of the spine. In 1999, she had undergone a hysterectomy that necessitated a blood transfusion. She has never smoked tobacco and does not consume alcohol or use illicit drugs. In the past she worked as a nurse’s aid in a nursing home. However, for the past several years she has stayed at home. Her only avocation of note is gardening.

Initial physical examination

The patient is intubated and sedated. Her temperature is 35.3°C (95.5°F), blood pressure 122/81 mm Hg, heart rate 83 beats per minute, and respiratory rate 14 on assist-controlled ventilator settings with an Fio₂ of 100% and a positive end-expiratory pressure of 5 cm H₂O.

Her pupils are round, equal, and reactive to light. Her face is symmetric and notable for hirsutism over the chin. Her neck is supple and without lymphadenopathy or thyromegaly.

Rhonchi can be heard at both lung bases. She has normal bowel sounds, and her abdomen is soft and nondistended, with no masses or palpable hepatosplenomegaly. She has no pedal edema on either side, and no clubbing or cyanosis. Her skin is intact, without rashes, lesions, or tattoos. She is able to withdraw from painful stimuli in all four extremities.

INITIAL TESTS PROVIDE A CLUE

The patient’s initial laboratory tests (Table 1) reveal low counts in all of her blood cell types. A peripheral blood smear shows crenated red blood cells with rare fragments, normal-appearing white blood cells (but in low numbers), and a low number of platelets.

1. Which of the following is the likely cause of this patient’s pancytopenia?

• Folate deficiency
• Gastrointestinal bleeding secondary to colon cancer
• 
  Acute myeloid leukemia
• Paroxysmal nocturnal hemoglobinuria
• Myelophthisis
• Other

Causes of pancytopenia are listed in Table 2.

Folate deficiency

Folate is necessary for thymidylate synthesis, a rate-limiting step in DNA synthesis. The minimum daily requirement for dietary folate intake is 50 μg.

Severe deficiency of folate has been reported to cause pancytopenia in alcoholics.¹ Abuse of alcohol leads to an abrupt decrease in serum folate (within 2 to 4 days of ceasing intake of proper amounts of folate, as in an alcoholic binge) by inhibiting its absorption in the proximal jejunum as well as its metabolism in the liver.² The resulting folate deficiency, if sustained, can develop into megaloblastosis in 5 to 10 weeks.

The duration of weakness and pallor reported by this patient would raise suspicion of folate deficiency if she had a history of malnutrition or of alcohol abuse, but she has neither. Further, her mean corpuscular volume is 82.5 fL, red blood cell folate 391 ng/mL (reference range 257–800 ng/mL), and serum vitamin B₁₂ 1,886 pg/mL (22–700 pg/mL), and she has no macro-ovalocytes or hypersegmented neutrophils on a peripheral blood smear. This makes folate or vitamin B₁₂ deficiency less likely.

Gastrointestinal bleeding due to colon cancer

Iron-deficiency anemia, hematochezia, melena, a change in bowel habits, and abdominal pain may be manifestations of colon cancer. Cancers of the colon originate from adenomatous polyps arising from the colonic mucosa.

The quantity of occult blood loss depends on the site of the tumor. Patients with tumors in the cecum or ascending colon lose an average of 9 mL/day, whereas those with tumors in the transverse, descending, or sigmoid colon or rectum lose less than 2 mL/day.³

Pertinent laboratory findings in iron-deficiency anemia are a low iron concentration, a low transferrin saturation, a depleted serum ferritin, and a normal to high total iron-binding capacity. An initial microcytic normochromic anemia eventually progresses to a microcytic hypochromic anemia that has a tendency to increasingly demonstrate anisocytosis and poikilocytosis.

Our patient’s symptoms, signs, and laboratory values (with normocytic normochromic anemia) are inconsistent with symptomatic colon cancer leading to iron-deficiency anemia.

 

 

Acute myeloid leukemia

Acute myeloid leukemia generally manifests with symptoms related to pancytopenia, with weakness and fatigability being the most common.⁴

In this condition, genetic alterations in hematopoietic precursor cells result in reduced differentiation capacity and accumulation of leukemic blasts in the bone marrow, peripheral blood, and other tissues.

Peripheral blood analysis usually reveals normocytic normochromic anemia with blasts. To establish a diagnosis of acute myeloid leukemia, one must observe at least 20% myeloblasts in the blood, the bone marrow, or both.

No blasts are seen on our patient’s peripheral blood smear, making acute myeloid leukemia less likely.

Paroxysmal nocturnal hemoglobinuria

Paroxysmal nocturnal hemoglobinuria is a possibility in the setting of intravascular hemolytic anemia, bone marrow failure, and thrombosis.

These processes are due to a defect in the glycosyl phosphatidyl inositol (GPI) anchor caused by an abnormality in the PIG-A gene. Partial or complete absence of the GPI anchor allows for activation of complement-mediated hemolysis. A diminished rate of hematopoiesis is presumably responsible for reticulocytopenia, granulocytopenia, or thrombocytopenia, though reticulocytosis can also be seen.^5,6 The highly thrombogenic state is believed to occur because of microparticles rich in phosphatidylserine.⁷

Our patient’s peripheral smear has rare fragmented red blood cells and lacks teardrop red cells. Although paroxysmal nocturnal hemoglobinuria does not have characteristic morphologic features in the peripheral blood, there are no signs of thrombosis in our patient. Her lactate dehydrogenase level is 395 U/L (reference range 100–220 U/L), and her haptoglobin level is less than 20 mg/dL (33–246). These findings could indicate a low level of intravascular hemolysis.

Myelophthisis

Myelophthisis refers to any disorder in which an abnormal cell process invades the bone marrow, damaging hematopoietic tissue. These processes include neoplastic diseases, storage disorders, and a variety of infections. A decrease in all three cell types may result, depending on the severity of invasion. Documented infectious causes include hepatitis viruses, Epstein-Barr virus, human immunodeficiency virus (HIV), mycobacteria, and fungi.

Our patient’s condition is likely due to a marrow-based process of uncertain etiology. In myelophthisic processes, one may see teardrop red cells, which are not seen in this patient’s smear. However, on her chest imaging, the finding of focal consolidations within the anterior segment of the right upper lobe and both lower lobes raises suspicion of an infectious cause.

CASE CONTINUED: SHE UNDERGOES DIAGNOSTIC TESTING

Let us recap some of the laboratory studies that document the extent of our patient’s pancytopenia and the pattern of her anemia:

• Hemoglobin 10.2 g/dL (reference range 11.5–15.5 g/dL)
• Platelet count 27 × 10⁹/L (150–400)
• Leukopenia with profound T-cell lymphopenia
• Iron 59 μg/dL (30–140)
• Total iron-binding capacity 110 μg/dL (210–415)
• Ferritin 3,004 ng/mL (18–300)
• Transferrin saturation 54% (11%–46%).

2. Which of the following would be the best test to obtain next?

• Bone marrow examination
• Blood cultures
• Tuberculin skin test
• Liver biopsy
• Positron emission tomography and CT

Our patient has unexplained pancytopenia. While all the tests listed above might shed light on her condition, a bone marrow examination would be the best test to obtain next.

Our patient undergoes bone marrow biopsy. Examination of the marrow shows histiocytes containing numerous small budding yeast forms with morphologic characteristics of Histoplasma capsulatum (Figure 1).

Urine histoplasma antigen studies are positive at greater than 39 ng/mL (normal 0, low positive < 0.6–3.9, moderate positive 4.0–19.9, high positive 20–39 ng/mL). A culture of the marrow subsequently grows this organism.

 

3. Which of the following tests would establish a definitive diagnosis in this patient?

• Methenamine silver stain of the marrow
• Serum antibody testing
• Fungal culture
• Peripheral blood smear
• Carbolfuchsin stain of marrow
• Urine histoplasma antigen

A prompt diagnosis is critical in patients with acute pulmonary histoplasmosis or progressive disseminated histoplasmosis because early treatment may shorten the clinical course and length of treatment and, in cases of disseminated histoplasmosis, prevent death.^8–10

Histopathologic examination of the bone marrow gives the most rapid results, although biopsy to obtain the tissue is invasive. It can give a definitive diagnosis if it reveals the typical 2- to 4-μm yeast structures of H capsulatum. These are observed on an aspirate smear of the patient’s bone marrow biopsy (Figure 1) and can be confirmed by methenamine silver or periodic acid-Schiff staining of the tissue.

Antibody detection is less practical because the antibodies take 2 to 6 weeks after infection to form.¹¹ Also, it is less useful in cases of disseminated infection because many of these patients are immunosuppressed.

Fungal culture remains the gold standard diagnostic test for histoplasmosis. However, results may take up to 1 month and may be falsely negative in less severe cases.

Histoplasma antigen testing is of greater utility in patients with severe disease, including cases of disseminated histoplasmosis. Rates of antigen detection approach 90% in urine specimens from non-AIDS patients with disseminated infection.¹² The urine assay has a greater sensitivity and specificity than the serum assay. The rate of detection is lower (ie, around 82%) in patients with acute pulmonary histoplasmosis when both the serum and urine specimens are tested.¹³

The immunoassay for histoplasma antigen is particularly useful for monitoring the response to therapy. Antigen levels should be measured before treatment is started and at 2 weeks, 1 month, and then approximately every 3 months during therapy.¹⁴ If the treatment is effective, antigens should decline by at least 20% in the first month of treatment and by another 20% in each of the following 3-month intervals. Antigen testing should be done every 3 months until a negative antigen level is achieved. The antigen level should also be followed for at least 6 months after treatment has stopped.¹⁴

HISTOPLASMA IS INHALED

H capsulatum is the cause of one of the most common pulmonary and systemic mycotic infections in the world, with hundreds of thousands of new cases annually. In areas where the soil is contaminated by bird or bat guano, the fungus is inhaled, resulting in an asymptomatic or a self-limiting influenza-like syndrome in an immunocompetent individual.¹⁵

An antigen-specific CD4⁺ T lymphocytemediated immunity occurs. The immune response of the host is thought to be fungistatic rather than fungicidal, resulting in a persistent inactive infection capable of reactivation in the presence of a host-pathogen imbalance.¹⁶

Most infections are asymptomatic or self-limited. For every 2,000 acute infections there is one that results in severe and progressive dissemination, usually in an immunocompromised host.^17,18

TREATMENT OF HISTOPLASMOSIS

4. What is the appropriate initial choice of treatment for a severe case of disseminated histoplasmosis?

• Amphotericin B in a lipid complex formulation (Abelcet)
• Itraconazole (Sporanox)
• Fluconazole (Diflucan)
• Ketoconazole (Nizoral)

Untreated, acute disseminated histoplasmosis can progress over a period of 2 to 12 weeks, ultimately killing the patient.^17,19

The leading therapies include amphotericin B in a lipid formulation and azole drugs, in particular itraconazole. Fluconazole and ketoconazole are not first-line options in severe cases because they are less predictably effective, and ketoconazole has a higher rate of side effects.^20–23 The current recommendation is to treat severely ill hospitalized patients with one of the liposomal formulations or the lipid complex formulation of amphotericin B. Itraconazole is used for patients who have mild to moderate symptoms and as a step-down therapy in patients who improve after initial use of amphotericin B.

CASE CONCLUDED: THE PATIENT RECOVERS

The patient’s symptoms improve after 2 weeks of treatment with intravenous amphotericin B lipid complex, followed by an oral itraconazole regimen. Two months later, her total leukocyte count and hemoglobin levels have normalized, and her platelet and T-cell counts have steadily increased but are still subnormal. Her urine histoplasma antigen levels have decreased but are still detectable after 6 months (Table 3). She continues to receive oral itraconazole for 1 year.

At the time of the initial patient encounter, there was no history of or obvious cause of immunosuppression in this patient. She was found to be HIV-negative and was subsequently diagnosed with “profound immunosuppression of unknown etiology” resulting in a low CD4 count.

The patient receives trimethoprim-sulfamethoxazole (Bactrim, Septra) and azithromycin (Zithromax) for prophylaxis against Pneumocystis carinii pneumonia and Mycobacterium avium intracellulare infection. Two months after the hospitalization, she recalls being at a corn maze 1 month before becoming ill.

A 54-year-old woman with a 1-month history of progressive weakness was transported to the emergency department of a local hospital when a family member found her unresponsive. Before this event, the patient had said she had been feeling tired and cold and looking pale for several weeks.

In the emergency department, her temperature was low. Cableomputed tomography (CT) of the head showed a 1.4-cm hyperdense extraaxial mass. Imaging of the chest showed focal consolidations within the anterior segment of the right upper lobe and the left and right lower lobes.

A urine toxicology screen was positive for acetaminophen (Tylenol), opiates, and benzodiazepines. She was given three doses of naloxone (Narcan), which raised her level of arousal; however, she later became obtunded again and was intubated and transferred to Cleveland Clinic.

A new CT scan of the head confirmed a small left temporal, extradural, calcified lesion with no mass effect or overt bleeding; it appeared most compatible with a solitary calcified meningioma—a likely benign finding.

Her medical history includes hypertension, type 2 diabetes (controlled with diet), and osteoarthritis of the spine. In 1999, she had undergone a hysterectomy that necessitated a blood transfusion. She has never smoked tobacco and does not consume alcohol or use illicit drugs. In the past she worked as a nurse’s aid in a nursing home. However, for the past several years she has stayed at home. Her only avocation of note is gardening.

Initial physical examination

The patient is intubated and sedated. Her temperature is 35.3°C (95.5°F), blood pressure 122/81 mm Hg, heart rate 83 beats per minute, and respiratory rate 14 on assist-controlled ventilator settings with an Fio₂ of 100% and a positive end-expiratory pressure of 5 cm H₂O.

Her pupils are round, equal, and reactive to light. Her face is symmetric and notable for hirsutism over the chin. Her neck is supple and without lymphadenopathy or thyromegaly.

Rhonchi can be heard at both lung bases. She has normal bowel sounds, and her abdomen is soft and nondistended, with no masses or palpable hepatosplenomegaly. She has no pedal edema on either side, and no clubbing or cyanosis. Her skin is intact, without rashes, lesions, or tattoos. She is able to withdraw from painful stimuli in all four extremities.

INITIAL TESTS PROVIDE A CLUE

The patient’s initial laboratory tests (Table 1) reveal low counts in all of her blood cell types. A peripheral blood smear shows crenated red blood cells with rare fragments, normal-appearing white blood cells (but in low numbers), and a low number of platelets.

1. Which of the following is the likely cause of this patient’s pancytopenia?

• Folate deficiency
• Gastrointestinal bleeding secondary to colon cancer
• 
  Acute myeloid leukemia
• Paroxysmal nocturnal hemoglobinuria
• Myelophthisis
• Other

Causes of pancytopenia are listed in Table 2.

Folate deficiency

Folate is necessary for thymidylate synthesis, a rate-limiting step in DNA synthesis. The minimum daily requirement for dietary folate intake is 50 μg.

Severe deficiency of folate has been reported to cause pancytopenia in alcoholics.¹ Abuse of alcohol leads to an abrupt decrease in serum folate (within 2 to 4 days of ceasing intake of proper amounts of folate, as in an alcoholic binge) by inhibiting its absorption in the proximal jejunum as well as its metabolism in the liver.² The resulting folate deficiency, if sustained, can develop into megaloblastosis in 5 to 10 weeks.

The duration of weakness and pallor reported by this patient would raise suspicion of folate deficiency if she had a history of malnutrition or of alcohol abuse, but she has neither. Further, her mean corpuscular volume is 82.5 fL, red blood cell folate 391 ng/mL (reference range 257–800 ng/mL), and serum vitamin B₁₂ 1,886 pg/mL (22–700 pg/mL), and she has no macro-ovalocytes or hypersegmented neutrophils on a peripheral blood smear. This makes folate or vitamin B₁₂ deficiency less likely.

Gastrointestinal bleeding due to colon cancer

Iron-deficiency anemia, hematochezia, melena, a change in bowel habits, and abdominal pain may be manifestations of colon cancer. Cancers of the colon originate from adenomatous polyps arising from the colonic mucosa.

The quantity of occult blood loss depends on the site of the tumor. Patients with tumors in the cecum or ascending colon lose an average of 9 mL/day, whereas those with tumors in the transverse, descending, or sigmoid colon or rectum lose less than 2 mL/day.³

Pertinent laboratory findings in iron-deficiency anemia are a low iron concentration, a low transferrin saturation, a depleted serum ferritin, and a normal to high total iron-binding capacity. An initial microcytic normochromic anemia eventually progresses to a microcytic hypochromic anemia that has a tendency to increasingly demonstrate anisocytosis and poikilocytosis.

Our patient’s symptoms, signs, and laboratory values (with normocytic normochromic anemia) are inconsistent with symptomatic colon cancer leading to iron-deficiency anemia.

 

 

Acute myeloid leukemia

Acute myeloid leukemia generally manifests with symptoms related to pancytopenia, with weakness and fatigability being the most common.⁴

In this condition, genetic alterations in hematopoietic precursor cells result in reduced differentiation capacity and accumulation of leukemic blasts in the bone marrow, peripheral blood, and other tissues.

Peripheral blood analysis usually reveals normocytic normochromic anemia with blasts. To establish a diagnosis of acute myeloid leukemia, one must observe at least 20% myeloblasts in the blood, the bone marrow, or both.

No blasts are seen on our patient’s peripheral blood smear, making acute myeloid leukemia less likely.

Paroxysmal nocturnal hemoglobinuria

Paroxysmal nocturnal hemoglobinuria is a possibility in the setting of intravascular hemolytic anemia, bone marrow failure, and thrombosis.

These processes are due to a defect in the glycosyl phosphatidyl inositol (GPI) anchor caused by an abnormality in the PIG-A gene. Partial or complete absence of the GPI anchor allows for activation of complement-mediated hemolysis. A diminished rate of hematopoiesis is presumably responsible for reticulocytopenia, granulocytopenia, or thrombocytopenia, though reticulocytosis can also be seen.^5,6 The highly thrombogenic state is believed to occur because of microparticles rich in phosphatidylserine.⁷

Our patient’s peripheral smear has rare fragmented red blood cells and lacks teardrop red cells. Although paroxysmal nocturnal hemoglobinuria does not have characteristic morphologic features in the peripheral blood, there are no signs of thrombosis in our patient. Her lactate dehydrogenase level is 395 U/L (reference range 100–220 U/L), and her haptoglobin level is less than 20 mg/dL (33–246). These findings could indicate a low level of intravascular hemolysis.

Myelophthisis

Myelophthisis refers to any disorder in which an abnormal cell process invades the bone marrow, damaging hematopoietic tissue. These processes include neoplastic diseases, storage disorders, and a variety of infections. A decrease in all three cell types may result, depending on the severity of invasion. Documented infectious causes include hepatitis viruses, Epstein-Barr virus, human immunodeficiency virus (HIV), mycobacteria, and fungi.

Our patient’s condition is likely due to a marrow-based process of uncertain etiology. In myelophthisic processes, one may see teardrop red cells, which are not seen in this patient’s smear. However, on her chest imaging, the finding of focal consolidations within the anterior segment of the right upper lobe and both lower lobes raises suspicion of an infectious cause.

CASE CONTINUED: SHE UNDERGOES DIAGNOSTIC TESTING

Let us recap some of the laboratory studies that document the extent of our patient’s pancytopenia and the pattern of her anemia:

• Hemoglobin 10.2 g/dL (reference range 11.5–15.5 g/dL)
• Platelet count 27 × 10⁹/L (150–400)
• Leukopenia with profound T-cell lymphopenia
• Iron 59 μg/dL (30–140)
• Total iron-binding capacity 110 μg/dL (210–415)
• Ferritin 3,004 ng/mL (18–300)
• Transferrin saturation 54% (11%–46%).

2. Which of the following would be the best test to obtain next?

• Bone marrow examination
• Blood cultures
• Tuberculin skin test
• Liver biopsy
• Positron emission tomography and CT

Our patient has unexplained pancytopenia. While all the tests listed above might shed light on her condition, a bone marrow examination would be the best test to obtain next.

Our patient undergoes bone marrow biopsy. Examination of the marrow shows histiocytes containing numerous small budding yeast forms with morphologic characteristics of Histoplasma capsulatum (Figure 1).

Urine histoplasma antigen studies are positive at greater than 39 ng/mL (normal 0, low positive < 0.6–3.9, moderate positive 4.0–19.9, high positive 20–39 ng/mL). A culture of the marrow subsequently grows this organism.

 

3. Which of the following tests would establish a definitive diagnosis in this patient?

• Methenamine silver stain of the marrow
• Serum antibody testing
• Fungal culture
• Peripheral blood smear
• Carbolfuchsin stain of marrow
• Urine histoplasma antigen

A prompt diagnosis is critical in patients with acute pulmonary histoplasmosis or progressive disseminated histoplasmosis because early treatment may shorten the clinical course and length of treatment and, in cases of disseminated histoplasmosis, prevent death.^8–10

Histopathologic examination of the bone marrow gives the most rapid results, although biopsy to obtain the tissue is invasive. It can give a definitive diagnosis if it reveals the typical 2- to 4-μm yeast structures of H capsulatum. These are observed on an aspirate smear of the patient’s bone marrow biopsy (Figure 1) and can be confirmed by methenamine silver or periodic acid-Schiff staining of the tissue.

Antibody detection is less practical because the antibodies take 2 to 6 weeks after infection to form.¹¹ Also, it is less useful in cases of disseminated infection because many of these patients are immunosuppressed.

Fungal culture remains the gold standard diagnostic test for histoplasmosis. However, results may take up to 1 month and may be falsely negative in less severe cases.

Histoplasma antigen testing is of greater utility in patients with severe disease, including cases of disseminated histoplasmosis. Rates of antigen detection approach 90% in urine specimens from non-AIDS patients with disseminated infection.¹² The urine assay has a greater sensitivity and specificity than the serum assay. The rate of detection is lower (ie, around 82%) in patients with acute pulmonary histoplasmosis when both the serum and urine specimens are tested.¹³

The immunoassay for histoplasma antigen is particularly useful for monitoring the response to therapy. Antigen levels should be measured before treatment is started and at 2 weeks, 1 month, and then approximately every 3 months during therapy.¹⁴ If the treatment is effective, antigens should decline by at least 20% in the first month of treatment and by another 20% in each of the following 3-month intervals. Antigen testing should be done every 3 months until a negative antigen level is achieved. The antigen level should also be followed for at least 6 months after treatment has stopped.¹⁴

HISTOPLASMA IS INHALED

H capsulatum is the cause of one of the most common pulmonary and systemic mycotic infections in the world, with hundreds of thousands of new cases annually. In areas where the soil is contaminated by bird or bat guano, the fungus is inhaled, resulting in an asymptomatic or a self-limiting influenza-like syndrome in an immunocompetent individual.¹⁵

An antigen-specific CD4⁺ T lymphocytemediated immunity occurs. The immune response of the host is thought to be fungistatic rather than fungicidal, resulting in a persistent inactive infection capable of reactivation in the presence of a host-pathogen imbalance.¹⁶

Most infections are asymptomatic or self-limited. For every 2,000 acute infections there is one that results in severe and progressive dissemination, usually in an immunocompromised host.^17,18

TREATMENT OF HISTOPLASMOSIS

4. What is the appropriate initial choice of treatment for a severe case of disseminated histoplasmosis?

• Amphotericin B in a lipid complex formulation (Abelcet)
• Itraconazole (Sporanox)
• Fluconazole (Diflucan)
• Ketoconazole (Nizoral)

Untreated, acute disseminated histoplasmosis can progress over a period of 2 to 12 weeks, ultimately killing the patient.^17,19

The leading therapies include amphotericin B in a lipid formulation and azole drugs, in particular itraconazole. Fluconazole and ketoconazole are not first-line options in severe cases because they are less predictably effective, and ketoconazole has a higher rate of side effects.^20–23 The current recommendation is to treat severely ill hospitalized patients with one of the liposomal formulations or the lipid complex formulation of amphotericin B. Itraconazole is used for patients who have mild to moderate symptoms and as a step-down therapy in patients who improve after initial use of amphotericin B.

CASE CONCLUDED: THE PATIENT RECOVERS

The patient’s symptoms improve after 2 weeks of treatment with intravenous amphotericin B lipid complex, followed by an oral itraconazole regimen. Two months later, her total leukocyte count and hemoglobin levels have normalized, and her platelet and T-cell counts have steadily increased but are still subnormal. Her urine histoplasma antigen levels have decreased but are still detectable after 6 months (Table 3). She continues to receive oral itraconazole for 1 year.

At the time of the initial patient encounter, there was no history of or obvious cause of immunosuppression in this patient. She was found to be HIV-negative and was subsequently diagnosed with “profound immunosuppression of unknown etiology” resulting in a low CD4 count.

The patient receives trimethoprim-sulfamethoxazole (Bactrim, Septra) and azithromycin (Zithromax) for prophylaxis against Pneumocystis carinii pneumonia and Mycobacterium avium intracellulare infection. Two months after the hospitalization, she recalls being at a corn maze 1 month before becoming ill.

A 54-year-old woman with a 1-month history of progressive weakness was transported to the emergency department of a local hospital when a family member found her unresponsive. Before this event, the patient had said she had been feeling tired and cold and looking pale for several weeks.

In the emergency department, her temperature was low. Cableomputed tomography (CT) of the head showed a 1.4-cm hyperdense extraaxial mass. Imaging of the chest showed focal consolidations within the anterior segment of the right upper lobe and the left and right lower lobes.

A urine toxicology screen was positive for acetaminophen (Tylenol), opiates, and benzodiazepines. She was given three doses of naloxone (Narcan), which raised her level of arousal; however, she later became obtunded again and was intubated and transferred to Cleveland Clinic.

A new CT scan of the head confirmed a small left temporal, extradural, calcified lesion with no mass effect or overt bleeding; it appeared most compatible with a solitary calcified meningioma—a likely benign finding.

Her medical history includes hypertension, type 2 diabetes (controlled with diet), and osteoarthritis of the spine. In 1999, she had undergone a hysterectomy that necessitated a blood transfusion. She has never smoked tobacco and does not consume alcohol or use illicit drugs. In the past she worked as a nurse’s aid in a nursing home. However, for the past several years she has stayed at home. Her only avocation of note is gardening.

Initial physical examination

The patient is intubated and sedated. Her temperature is 35.3°C (95.5°F), blood pressure 122/81 mm Hg, heart rate 83 beats per minute, and respiratory rate 14 on assist-controlled ventilator settings with an Fio₂ of 100% and a positive end-expiratory pressure of 5 cm H₂O.

Her pupils are round, equal, and reactive to light. Her face is symmetric and notable for hirsutism over the chin. Her neck is supple and without lymphadenopathy or thyromegaly.

Rhonchi can be heard at both lung bases. She has normal bowel sounds, and her abdomen is soft and nondistended, with no masses or palpable hepatosplenomegaly. She has no pedal edema on either side, and no clubbing or cyanosis. Her skin is intact, without rashes, lesions, or tattoos. She is able to withdraw from painful stimuli in all four extremities.

INITIAL TESTS PROVIDE A CLUE

The patient’s initial laboratory tests (Table 1) reveal low counts in all of her blood cell types. A peripheral blood smear shows crenated red blood cells with rare fragments, normal-appearing white blood cells (but in low numbers), and a low number of platelets.

1. Which of the following is the likely cause of this patient’s pancytopenia?

• Folate deficiency
• Gastrointestinal bleeding secondary to colon cancer
• 
  Acute myeloid leukemia
• Paroxysmal nocturnal hemoglobinuria
• Myelophthisis
• Other

Causes of pancytopenia are listed in Table 2.

Folate deficiency

Folate is necessary for thymidylate synthesis, a rate-limiting step in DNA synthesis. The minimum daily requirement for dietary folate intake is 50 μg.

Severe deficiency of folate has been reported to cause pancytopenia in alcoholics.¹ Abuse of alcohol leads to an abrupt decrease in serum folate (within 2 to 4 days of ceasing intake of proper amounts of folate, as in an alcoholic binge) by inhibiting its absorption in the proximal jejunum as well as its metabolism in the liver.² The resulting folate deficiency, if sustained, can develop into megaloblastosis in 5 to 10 weeks.

The duration of weakness and pallor reported by this patient would raise suspicion of folate deficiency if she had a history of malnutrition or of alcohol abuse, but she has neither. Further, her mean corpuscular volume is 82.5 fL, red blood cell folate 391 ng/mL (reference range 257–800 ng/mL), and serum vitamin B₁₂ 1,886 pg/mL (22–700 pg/mL), and she has no macro-ovalocytes or hypersegmented neutrophils on a peripheral blood smear. This makes folate or vitamin B₁₂ deficiency less likely.

Gastrointestinal bleeding due to colon cancer

Iron-deficiency anemia, hematochezia, melena, a change in bowel habits, and abdominal pain may be manifestations of colon cancer. Cancers of the colon originate from adenomatous polyps arising from the colonic mucosa.

The quantity of occult blood loss depends on the site of the tumor. Patients with tumors in the cecum or ascending colon lose an average of 9 mL/day, whereas those with tumors in the transverse, descending, or sigmoid colon or rectum lose less than 2 mL/day.³

Pertinent laboratory findings in iron-deficiency anemia are a low iron concentration, a low transferrin saturation, a depleted serum ferritin, and a normal to high total iron-binding capacity. An initial microcytic normochromic anemia eventually progresses to a microcytic hypochromic anemia that has a tendency to increasingly demonstrate anisocytosis and poikilocytosis.

Our patient’s symptoms, signs, and laboratory values (with normocytic normochromic anemia) are inconsistent with symptomatic colon cancer leading to iron-deficiency anemia.

 

 

Acute myeloid leukemia

Acute myeloid leukemia generally manifests with symptoms related to pancytopenia, with weakness and fatigability being the most common.⁴

In this condition, genetic alterations in hematopoietic precursor cells result in reduced differentiation capacity and accumulation of leukemic blasts in the bone marrow, peripheral blood, and other tissues.

Peripheral blood analysis usually reveals normocytic normochromic anemia with blasts. To establish a diagnosis of acute myeloid leukemia, one must observe at least 20% myeloblasts in the blood, the bone marrow, or both.

No blasts are seen on our patient’s peripheral blood smear, making acute myeloid leukemia less likely.

Paroxysmal nocturnal hemoglobinuria

Paroxysmal nocturnal hemoglobinuria is a possibility in the setting of intravascular hemolytic anemia, bone marrow failure, and thrombosis.

These processes are due to a defect in the glycosyl phosphatidyl inositol (GPI) anchor caused by an abnormality in the PIG-A gene. Partial or complete absence of the GPI anchor allows for activation of complement-mediated hemolysis. A diminished rate of hematopoiesis is presumably responsible for reticulocytopenia, granulocytopenia, or thrombocytopenia, though reticulocytosis can also be seen.^5,6 The highly thrombogenic state is believed to occur because of microparticles rich in phosphatidylserine.⁷

Our patient’s peripheral smear has rare fragmented red blood cells and lacks teardrop red cells. Although paroxysmal nocturnal hemoglobinuria does not have characteristic morphologic features in the peripheral blood, there are no signs of thrombosis in our patient. Her lactate dehydrogenase level is 395 U/L (reference range 100–220 U/L), and her haptoglobin level is less than 20 mg/dL (33–246). These findings could indicate a low level of intravascular hemolysis.

Myelophthisis

Myelophthisis refers to any disorder in which an abnormal cell process invades the bone marrow, damaging hematopoietic tissue. These processes include neoplastic diseases, storage disorders, and a variety of infections. A decrease in all three cell types may result, depending on the severity of invasion. Documented infectious causes include hepatitis viruses, Epstein-Barr virus, human immunodeficiency virus (HIV), mycobacteria, and fungi.

Our patient’s condition is likely due to a marrow-based process of uncertain etiology. In myelophthisic processes, one may see teardrop red cells, which are not seen in this patient’s smear. However, on her chest imaging, the finding of focal consolidations within the anterior segment of the right upper lobe and both lower lobes raises suspicion of an infectious cause.

CASE CONTINUED: SHE UNDERGOES DIAGNOSTIC TESTING

Let us recap some of the laboratory studies that document the extent of our patient’s pancytopenia and the pattern of her anemia:

• Hemoglobin 10.2 g/dL (reference range 11.5–15.5 g/dL)
• Platelet count 27 × 10⁹/L (150–400)
• Leukopenia with profound T-cell lymphopenia
• Iron 59 μg/dL (30–140)
• Total iron-binding capacity 110 μg/dL (210–415)
• Ferritin 3,004 ng/mL (18–300)
• Transferrin saturation 54% (11%–46%).

2. Which of the following would be the best test to obtain next?

• Bone marrow examination
• Blood cultures
• Tuberculin skin test
• Liver biopsy
• Positron emission tomography and CT

Our patient has unexplained pancytopenia. While all the tests listed above might shed light on her condition, a bone marrow examination would be the best test to obtain next.

Our patient undergoes bone marrow biopsy. Examination of the marrow shows histiocytes containing numerous small budding yeast forms with morphologic characteristics of Histoplasma capsulatum (Figure 1).

Urine histoplasma antigen studies are positive at greater than 39 ng/mL (normal 0, low positive < 0.6–3.9, moderate positive 4.0–19.9, high positive 20–39 ng/mL). A culture of the marrow subsequently grows this organism.

 

3. Which of the following tests would establish a definitive diagnosis in this patient?

• Methenamine silver stain of the marrow
• Serum antibody testing
• Fungal culture
• Peripheral blood smear
• Carbolfuchsin stain of marrow
• Urine histoplasma antigen

A prompt diagnosis is critical in patients with acute pulmonary histoplasmosis or progressive disseminated histoplasmosis because early treatment may shorten the clinical course and length of treatment and, in cases of disseminated histoplasmosis, prevent death.^8–10

Histopathologic examination of the bone marrow gives the most rapid results, although biopsy to obtain the tissue is invasive. It can give a definitive diagnosis if it reveals the typical 2- to 4-μm yeast structures of H capsulatum. These are observed on an aspirate smear of the patient’s bone marrow biopsy (Figure 1) and can be confirmed by methenamine silver or periodic acid-Schiff staining of the tissue.

Antibody detection is less practical because the antibodies take 2 to 6 weeks after infection to form.¹¹ Also, it is less useful in cases of disseminated infection because many of these patients are immunosuppressed.

Fungal culture remains the gold standard diagnostic test for histoplasmosis. However, results may take up to 1 month and may be falsely negative in less severe cases.

Histoplasma antigen testing is of greater utility in patients with severe disease, including cases of disseminated histoplasmosis. Rates of antigen detection approach 90% in urine specimens from non-AIDS patients with disseminated infection.¹² The urine assay has a greater sensitivity and specificity than the serum assay. The rate of detection is lower (ie, around 82%) in patients with acute pulmonary histoplasmosis when both the serum and urine specimens are tested.¹³

The immunoassay for histoplasma antigen is particularly useful for monitoring the response to therapy. Antigen levels should be measured before treatment is started and at 2 weeks, 1 month, and then approximately every 3 months during therapy.¹⁴ If the treatment is effective, antigens should decline by at least 20% in the first month of treatment and by another 20% in each of the following 3-month intervals. Antigen testing should be done every 3 months until a negative antigen level is achieved. The antigen level should also be followed for at least 6 months after treatment has stopped.¹⁴

HISTOPLASMA IS INHALED

H capsulatum is the cause of one of the most common pulmonary and systemic mycotic infections in the world, with hundreds of thousands of new cases annually. In areas where the soil is contaminated by bird or bat guano, the fungus is inhaled, resulting in an asymptomatic or a self-limiting influenza-like syndrome in an immunocompetent individual.¹⁵

An antigen-specific CD4⁺ T lymphocytemediated immunity occurs. The immune response of the host is thought to be fungistatic rather than fungicidal, resulting in a persistent inactive infection capable of reactivation in the presence of a host-pathogen imbalance.¹⁶

Most infections are asymptomatic or self-limited. For every 2,000 acute infections there is one that results in severe and progressive dissemination, usually in an immunocompromised host.^17,18

TREATMENT OF HISTOPLASMOSIS

4. What is the appropriate initial choice of treatment for a severe case of disseminated histoplasmosis?

• Amphotericin B in a lipid complex formulation (Abelcet)
• Itraconazole (Sporanox)
• Fluconazole (Diflucan)
• Ketoconazole (Nizoral)

Untreated, acute disseminated histoplasmosis can progress over a period of 2 to 12 weeks, ultimately killing the patient.^17,19

The leading therapies include amphotericin B in a lipid formulation and azole drugs, in particular itraconazole. Fluconazole and ketoconazole are not first-line options in severe cases because they are less predictably effective, and ketoconazole has a higher rate of side effects.^20–23 The current recommendation is to treat severely ill hospitalized patients with one of the liposomal formulations or the lipid complex formulation of amphotericin B. Itraconazole is used for patients who have mild to moderate symptoms and as a step-down therapy in patients who improve after initial use of amphotericin B.

CASE CONCLUDED: THE PATIENT RECOVERS

The patient’s symptoms improve after 2 weeks of treatment with intravenous amphotericin B lipid complex, followed by an oral itraconazole regimen. Two months later, her total leukocyte count and hemoglobin levels have normalized, and her platelet and T-cell counts have steadily increased but are still subnormal. Her urine histoplasma antigen levels have decreased but are still detectable after 6 months (Table 3). She continues to receive oral itraconazole for 1 year.

At the time of the initial patient encounter, there was no history of or obvious cause of immunosuppression in this patient. She was found to be HIV-negative and was subsequently diagnosed with “profound immunosuppression of unknown etiology” resulting in a low CD4 count.

The patient receives trimethoprim-sulfamethoxazole (Bactrim, Septra) and azithromycin (Zithromax) for prophylaxis against Pneumocystis carinii pneumonia and Mycobacterium avium intracellulare infection. Two months after the hospitalization, she recalls being at a corn maze 1 month before becoming ill.

A 25-year-old man presented to his primary care physician with generalized malaise. His symptoms started around 2 months earlier with progressive fatigue, nausea, decreased appetite, and weight loss (15 lb in 2 months). He denied having fever, chills, night sweats, abdominal pain, diarrhea, melena, or hematochezia.

His medical history was remarkable only for depression, well controlled with sertraline (Zoloft), which he started taking 3 years ago. He was not taking any other prescribed, over-the-counter, or herbal medications.

He had no family history of cancer or liver disease. He did not smoke and rarely drank alcohol. He had never used recreational drugs. He was sexually active with one female partner, used condoms for protection, and had never been diagnosed with a sexually transmitted disease. He had not traveled recently and had not been exposed to any pet.

On physical examination, the patient was alert and oriented. He was afebrile, his heart rate was 90 beats per minute and regular, his respiratory rate was 18 breaths per minute, and his blood pressure was 125/77 mm Hg. Auscultation of the chest was clear. His heart sounds were normal, and there was no murmur, gallop, or rub. His right upper quadrant was mildly tender, and his liver was palpably enlarged. He had no peripheral edema, clubbing, rash, telangiectasia, or other skin changes. Examination of the joints revealed no warmth, swelling, or erythema.

The patient’s laboratory values on admission are shown in Table 1. Of note, his serum alkaline phosphatase level was 1,307 U/L (reference range 40–150 U/L).

LIVER TESTS CAN NARROW THE DIAGNOSIS

The most commonly used laboratory tests of the liver can be classified into those that measure either:

• Liver synthetic function (eg, the serum albumin and bilirubin concentrations and the prothrombin time) or
• Liver damage, as reflected by the serum concentrations of the enzymes alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase, and gamma-glutamyltransferase (GGT).^1,2

ALT and AST are normally concentrated in the hepatocytes and thus, when present in the serum in elevated concentrations, are markers of liver cell injury. The serum levels of these enzymes start to increase within a few hours of liver cell injury as they leak out of the cells via the damaged cell membrane. AST is less liver-specific than ALT, since AST levels can be elevated not only in liver injury but also in muscle, cardiac, and red blood cell injury.^3,4

Alkaline phosphatase is actually a heterogeneous group of enzymes found mainly in liver and bone cells. Hepatic alkaline phosphatase is concentrated near the biliary canalicular membrane of the hepatocyte. Accordingly, increased levels of hepatic alkaline phosphatase are mainly seen in liver diseases that predominantly affect the biliary system.³

GGT is also concentrated in hepatic biliary epithelial cells, and thus GGT elevation is another marker of hepatobiliary disease. In fact, measuring the GGT level can help to determine whether an isolated elevation of alkaline phosphatase is due to liver injury.^2,3

Accordingly, liver diseases can be classified into two broad categories:

• Hepatocellular injury, in which the primary injury occurs to the hepatocytes
• Cholestatic injury, in which the primary injury is to the bile ducts.

In the former, elevated levels of ALT and AST predominate, while in the latter, elevated alkaline phosphatase is the main finding.³

 

WHAT TEST NEXT FOR OUR PATIENT?

1. What is the next most appropriate diagnostic step for our patient?

• Liver biopsy
• Ultrasonography of the liver
• Computed tomography (CT) of the liver
• Observation

Our patient has an elevated GGT level, which suggests that his elevated alkaline phosphatase is of hepatic rather than bony origin. Moreover, a serum alkaline phosphatase level that is elevated out of proportion to the aminotransferase levels reflects cholestatic liver injury.

Cholestatic liver diseases can be classified into two broad categories based on whether the injury affects the microscopic intrahepatic bile ducts (intrahepatic cholestasis) or extrahepatic large bile duct (extrahepatic cholestasis). The simplest diagnostic test to differentiate between the two is ultrasonography, which can identify extrahepatic biliary obstruction fairly well. Therefore, the diagnostic workup of cholestatic liver injury should start with ultrasonography of the liver to differentiate between intrahepatic and extrahepatic processes (Figure 1).

CASE CONTINUED: ULTRASONOGRAPHY IS MOSTLY NORMAL

Ultrasonography of the right upper quadrant revealed that the liver had normal echogenicity and was mildly enlarged. There was no focal hepatic lesion. The gallbladder appeared normal, with no stones or sludge. No dilated intrahepatic or extrahepatic biliary ducts were seen. The common bile duct measured 4 mm. A small amount of ascites not amenable to paracentesis was present.

Thus, in the absence of biliary dilation on ultrasonography, we are dealing with an intrahepatic cholestatic process.

CAUSES OF CHOLESTATIC LIVER DISEASE

Table 2 lists the common causes of cholestatic liver disease.

Viral hepatitis

Viral hepatitis most often produces a hepatocellular pattern of injury (ie, AST and ALT elevations predominate). However, in rare cases it can cause a cholestatic pattern of injury.

Our patient subsequently had serologic tests for viral hepatitis, including hepatitis A, B, and C, and the results were negative.

Autoimmune liver disease

The three most common forms of autoimmune liver disease are autoimmune hepatitis, primary biliary cirrhosis, and primary sclerosing cholangitis.

Autoimmune hepatitis is characterized by high serum ALT and AST levels, whereas primary biliary cirrhosis and primary sclerosing cholangitis are associated with predominant elevations of alkaline phosphatase, since they are cholestatic disorders.

Our patient’s alkaline phosphatase level was much higher than his ALT and AST levels, making the latter two diseases more likely.

Primary biliary cirrhosis (and autoimmune hepatitis) are associated with autoantibodies in the serum, such as antinuclear antibody, smooth muscle antibody, and antimitochondrial antibody.

Our patient subsequently was tested for these antibodies, and the results were negative.

Primary sclerosing cholangitis usually affects the extrahepatic biliary system. Thus, if it is present, abnormalities should be seen on imaging.

As mentioned previously, no dilated intrahepatic or extrahepatic biliary ducts were seen on ultrasonography in our patient. Moreover, primary sclerosing cholangitis is associated with inflammatory bowel disease, particularly ulcerative colitis, which our patient did not have.

Drug-induced liver injury

Drug-induced liver injury is a common cause of cholestatic liver disease. However, our patient was not taking any prescribed, over-the-counter, or herbal medications. Additionally, he denied heavy alcohol use.

Infiltrative disorders

Infiltrative disorders such as amyloidosis, sarcoidosis, or lymphoma should be considered in the differential diagnosis of cholestatic liver disease. A clue to a possible infiltrative process is a markedly elevated level of alkaline phosphatase with a mildly increased serum bilirubin concentration, both of which our patient had.

 

AFTER ULTRASONOGRAPHY, WHAT IS THE NEXT STEP?

2. Which of the following is the next most appropriate diagnostic test for our patient?

• Endoscopic retrograde cholangiopancreatography (ERCP)
• Magnetic resonance cholangiopancreatography (MRCP)
• Liver biopsy
• CT of the abdomen

Figure 1 shows a proposed algorithm for evaluating increased alkaline phosphatase levels.

If there is no biliary duct dilation on ultrasonography, then abnormal levels of alkaline phosphatase most likely represent an intrahepatic pattern of cholestatic liver injury. Therefore, additional imaging with CT or magnetic resonance imaging is of limited diagnostic value. ERCP is used today for therapy rather than diagnosis, so its use is limited to patients known to have dilated biliary ducts on imaging. Liver biopsy, however, can provide useful findings.

Case continued: He undergoes biopsy

Our patient underwent transjugular liver biopsy. During the procedure, transjugular venography showed stenosis in the right, middle, and left hepatic veins and the hepatic portion of the inferior vena cava, consistent with Budd-Chiari syndrome.

The liver biopsy specimen was positive for extensive deposition of slight eosinophilic and amorphous material in a sinusoidal pattern in the liver parenchyma, as well as in the portal tracts, with markedly atrophic hepatocytes. Congo red birefringence confirmed the diagnosis of amyloidosis. The immunohistochemical phenotype was positive for kappa light chains, which is diagnostic for primary-type amyloidosis, also called amyloidosis of light chain composition, or AL.

Bone marrow aspiration and bone marrow biopsy were performed and showed 22% plasma cells, well above the normal range (0–2%), consistent with the diagnosis of multiple myeloma.

BUDD-CHIARI SYNDROME: A CHALLENGING DIAGNOSIS

Budd-Chiari syndrome is a rare condition characterized by obstruction of venous outflow from the liver at a site that may vary from the small hepatic veins up to the inferior vena cava or even the right atrium.^5,6 Obstruction of hepatic venous outflow leads to sinusoidal congestion and hypoxic damage of the hepatocytes.⁷ Hypoxia and necrosis of the hepatocytes result in the release of free radicals. Cirrhosis can eventually occur secondary to ischemic necrosis of hepatocytes and hepatic fibrosis.⁸

The estimated incidence of this syndrome is 1 in 2.5 million persons per year.⁷ It is more prevalent in women and young adults.⁸

Heterogeneous in its causes and manifestations

In about 75% of patients with Budd-Chiari syndrome, a hereditary or acquired hematologic abnormality or thrombotic diathesis can be found.^8–10 Some of the major causes are summarized in Table 3. The most common causes are hematologic diseases, especially myeloproliferative disorders.^7,8,11

Budd-Chiari syndrome is also heterogeneous in its manifestations, which depend on the extent of the occlusion, on the acuteness of the obstruction, and on whether venous collateral circulation has developed to decompress the liver sinusoids.^9,12,13 Therefore, on the basis of its clinical manifestations, it can be classified as fulminant, acute, subacute, or chronic.^12–16

The fulminant form presents with hepatic encephalopathy within 8 weeks after the development of jaundice. The subacute form, which is the most common, has a more insidious onset in which hepatic sinusoids are decompressed by portal and hepatic venous collateral circulation. The patient usually presents with abdominal pain, ascites, hepatomegaly, nausea, vomiting, and mild jaundice. Finally the chronic form presents as complications of cirrhosis.^12–16

Imaging plays an important role in diagnosing Budd-Chiari syndrome

Imaging plays an important role in detecting and classifying Budd-Chiari syndrome.

Duplex ultrasonography is useful for detecting this syndrome and has a sensitivity and specificity of 85%.⁹

CT and magnetic resonance imaging can also help in the diagnosis by showing thrombosis, obstruction, or occlusion in the hepatic vein or the inferior vena cava.⁵

Venography is the gold standard for diagnosis. However, it should be performed only if noninvasive tests are negative or nondiagnostic and there is a high clinical suspicion of this disease.¹⁷ Budd-Chiari syndrome has a characteristic pattern on venography known as “spider web,” which is due to the formation of venous collaterals to bypass the occluded hepatic veins.⁹

Liver biopsy is not necessarily required to confirm the diagnosis of Budd-Chiari syndrome, but it can help in diagnosing the acute or subacute forms and also in ruling out other causes. Histologic findings can include centrizonal congestion, loss of hepatocytes, hemorrhage, and fibrosis.^18,19 Regenerative nodules are found in about 25% of patients.¹⁹

 

TREATING BUDD-CHIARI SYNDROME

The primary goal of treatment is to prevent further extension of the venous thrombosis in the hepatic veins, in their collaterals, and in the intrahepatic and extrahepatic portal venous system. Resolution of hepatic congestion improves liver perfusion and preserves function of the hepatocytes.

Anticoagulation is recommended in the early stages. Heparin therapy should be initiated and subsequently switched to warfarin with the goal of achieving an international normalized ratio of the prothrombin time of 2.0 to 2.5.^8,9,19

Thrombolysis is effective in the acute form.^20,21 Recanalization, including percutaneous or transhepatic angioplasty of localized segments of the narrowed hepatic veins or inferior vena cava, has long-term patency rates of 80% to 90%.²²

If thrombolytic therapy and angioplasty are unsuccessful, a transjugular intrahepatic portosystemic shunt or a surgical procedure (side-to-side portocaval shunt, central splenorenal shunt, or mesocaval shunt) should be considered.⁹

Liver transplantation is another treatment option in those with fulminant Budd-Chiari syndrome or advanced liver cirrhosis.⁸

PROGNOSIS HAS IMPROVED

The prognosis of Budd-Chiari syndrome has improved, thanks to both earlier diagnosis and new treatments. The 1-year survival rate, which was about 60% before 1985, has increased to more than 80% in recent cohort studies.¹⁹

Studies have shown that the Child-Pugh score, which is based on a combination of serum albumin, bilirubin, prothrombin time, encephalopathy, and ascites, can be considered as an independent prognostic factor. A lower Child-Pugh score and a younger age are associated with a good prognosis.^19,23,24 (The Child-Pugh score cannot be applied to our patient because he does not have cirrhosis.)

What happened to our patient?

Our patient was started on anticoagulation for his Budd-Chiari syndrome and on bortezomib (Velcade) and dexamethasone for his multiple myeloma. He achieved remarkable improvement in his liver function tests. Follow-up duplex ultrasonography 1 month after discharge revealed that the stenosis in the hepatic veins had resolved. He is following up with the oncology clinic for management of his multiple myeloma.

A 25-year-old man presented to his primary care physician with generalized malaise. His symptoms started around 2 months earlier with progressive fatigue, nausea, decreased appetite, and weight loss (15 lb in 2 months). He denied having fever, chills, night sweats, abdominal pain, diarrhea, melena, or hematochezia.

His medical history was remarkable only for depression, well controlled with sertraline (Zoloft), which he started taking 3 years ago. He was not taking any other prescribed, over-the-counter, or herbal medications.

He had no family history of cancer or liver disease. He did not smoke and rarely drank alcohol. He had never used recreational drugs. He was sexually active with one female partner, used condoms for protection, and had never been diagnosed with a sexually transmitted disease. He had not traveled recently and had not been exposed to any pet.

On physical examination, the patient was alert and oriented. He was afebrile, his heart rate was 90 beats per minute and regular, his respiratory rate was 18 breaths per minute, and his blood pressure was 125/77 mm Hg. Auscultation of the chest was clear. His heart sounds were normal, and there was no murmur, gallop, or rub. His right upper quadrant was mildly tender, and his liver was palpably enlarged. He had no peripheral edema, clubbing, rash, telangiectasia, or other skin changes. Examination of the joints revealed no warmth, swelling, or erythema.

The patient’s laboratory values on admission are shown in Table 1. Of note, his serum alkaline phosphatase level was 1,307 U/L (reference range 40–150 U/L).

LIVER TESTS CAN NARROW THE DIAGNOSIS

The most commonly used laboratory tests of the liver can be classified into those that measure either:

• Liver synthetic function (eg, the serum albumin and bilirubin concentrations and the prothrombin time) or
• Liver damage, as reflected by the serum concentrations of the enzymes alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase, and gamma-glutamyltransferase (GGT).^1,2

ALT and AST are normally concentrated in the hepatocytes and thus, when present in the serum in elevated concentrations, are markers of liver cell injury. The serum levels of these enzymes start to increase within a few hours of liver cell injury as they leak out of the cells via the damaged cell membrane. AST is less liver-specific than ALT, since AST levels can be elevated not only in liver injury but also in muscle, cardiac, and red blood cell injury.^3,4

Alkaline phosphatase is actually a heterogeneous group of enzymes found mainly in liver and bone cells. Hepatic alkaline phosphatase is concentrated near the biliary canalicular membrane of the hepatocyte. Accordingly, increased levels of hepatic alkaline phosphatase are mainly seen in liver diseases that predominantly affect the biliary system.³

GGT is also concentrated in hepatic biliary epithelial cells, and thus GGT elevation is another marker of hepatobiliary disease. In fact, measuring the GGT level can help to determine whether an isolated elevation of alkaline phosphatase is due to liver injury.^2,3

Accordingly, liver diseases can be classified into two broad categories:

• Hepatocellular injury, in which the primary injury occurs to the hepatocytes
• Cholestatic injury, in which the primary injury is to the bile ducts.

In the former, elevated levels of ALT and AST predominate, while in the latter, elevated alkaline phosphatase is the main finding.³

 

WHAT TEST NEXT FOR OUR PATIENT?

1. What is the next most appropriate diagnostic step for our patient?

• Liver biopsy
• Ultrasonography of the liver
• Computed tomography (CT) of the liver
• Observation

Our patient has an elevated GGT level, which suggests that his elevated alkaline phosphatase is of hepatic rather than bony origin. Moreover, a serum alkaline phosphatase level that is elevated out of proportion to the aminotransferase levels reflects cholestatic liver injury.

Cholestatic liver diseases can be classified into two broad categories based on whether the injury affects the microscopic intrahepatic bile ducts (intrahepatic cholestasis) or extrahepatic large bile duct (extrahepatic cholestasis). The simplest diagnostic test to differentiate between the two is ultrasonography, which can identify extrahepatic biliary obstruction fairly well. Therefore, the diagnostic workup of cholestatic liver injury should start with ultrasonography of the liver to differentiate between intrahepatic and extrahepatic processes (Figure 1).

CASE CONTINUED: ULTRASONOGRAPHY IS MOSTLY NORMAL

Ultrasonography of the right upper quadrant revealed that the liver had normal echogenicity and was mildly enlarged. There was no focal hepatic lesion. The gallbladder appeared normal, with no stones or sludge. No dilated intrahepatic or extrahepatic biliary ducts were seen. The common bile duct measured 4 mm. A small amount of ascites not amenable to paracentesis was present.

Thus, in the absence of biliary dilation on ultrasonography, we are dealing with an intrahepatic cholestatic process.

CAUSES OF CHOLESTATIC LIVER DISEASE

Table 2 lists the common causes of cholestatic liver disease.

Viral hepatitis

Viral hepatitis most often produces a hepatocellular pattern of injury (ie, AST and ALT elevations predominate). However, in rare cases it can cause a cholestatic pattern of injury.

Our patient subsequently had serologic tests for viral hepatitis, including hepatitis A, B, and C, and the results were negative.

Autoimmune liver disease

The three most common forms of autoimmune liver disease are autoimmune hepatitis, primary biliary cirrhosis, and primary sclerosing cholangitis.

Autoimmune hepatitis is characterized by high serum ALT and AST levels, whereas primary biliary cirrhosis and primary sclerosing cholangitis are associated with predominant elevations of alkaline phosphatase, since they are cholestatic disorders.

Our patient’s alkaline phosphatase level was much higher than his ALT and AST levels, making the latter two diseases more likely.

Primary biliary cirrhosis (and autoimmune hepatitis) are associated with autoantibodies in the serum, such as antinuclear antibody, smooth muscle antibody, and antimitochondrial antibody.

Our patient subsequently was tested for these antibodies, and the results were negative.

Primary sclerosing cholangitis usually affects the extrahepatic biliary system. Thus, if it is present, abnormalities should be seen on imaging.

As mentioned previously, no dilated intrahepatic or extrahepatic biliary ducts were seen on ultrasonography in our patient. Moreover, primary sclerosing cholangitis is associated with inflammatory bowel disease, particularly ulcerative colitis, which our patient did not have.

Drug-induced liver injury

Drug-induced liver injury is a common cause of cholestatic liver disease. However, our patient was not taking any prescribed, over-the-counter, or herbal medications. Additionally, he denied heavy alcohol use.

Infiltrative disorders

Infiltrative disorders such as amyloidosis, sarcoidosis, or lymphoma should be considered in the differential diagnosis of cholestatic liver disease. A clue to a possible infiltrative process is a markedly elevated level of alkaline phosphatase with a mildly increased serum bilirubin concentration, both of which our patient had.

 

AFTER ULTRASONOGRAPHY, WHAT IS THE NEXT STEP?

2. Which of the following is the next most appropriate diagnostic test for our patient?

• Endoscopic retrograde cholangiopancreatography (ERCP)
• Magnetic resonance cholangiopancreatography (MRCP)
• Liver biopsy
• CT of the abdomen

Figure 1 shows a proposed algorithm for evaluating increased alkaline phosphatase levels.

If there is no biliary duct dilation on ultrasonography, then abnormal levels of alkaline phosphatase most likely represent an intrahepatic pattern of cholestatic liver injury. Therefore, additional imaging with CT or magnetic resonance imaging is of limited diagnostic value. ERCP is used today for therapy rather than diagnosis, so its use is limited to patients known to have dilated biliary ducts on imaging. Liver biopsy, however, can provide useful findings.

Case continued: He undergoes biopsy

Our patient underwent transjugular liver biopsy. During the procedure, transjugular venography showed stenosis in the right, middle, and left hepatic veins and the hepatic portion of the inferior vena cava, consistent with Budd-Chiari syndrome.

The liver biopsy specimen was positive for extensive deposition of slight eosinophilic and amorphous material in a sinusoidal pattern in the liver parenchyma, as well as in the portal tracts, with markedly atrophic hepatocytes. Congo red birefringence confirmed the diagnosis of amyloidosis. The immunohistochemical phenotype was positive for kappa light chains, which is diagnostic for primary-type amyloidosis, also called amyloidosis of light chain composition, or AL.

Bone marrow aspiration and bone marrow biopsy were performed and showed 22% plasma cells, well above the normal range (0–2%), consistent with the diagnosis of multiple myeloma.

BUDD-CHIARI SYNDROME: A CHALLENGING DIAGNOSIS

Budd-Chiari syndrome is a rare condition characterized by obstruction of venous outflow from the liver at a site that may vary from the small hepatic veins up to the inferior vena cava or even the right atrium.^5,6 Obstruction of hepatic venous outflow leads to sinusoidal congestion and hypoxic damage of the hepatocytes.⁷ Hypoxia and necrosis of the hepatocytes result in the release of free radicals. Cirrhosis can eventually occur secondary to ischemic necrosis of hepatocytes and hepatic fibrosis.⁸

The estimated incidence of this syndrome is 1 in 2.5 million persons per year.⁷ It is more prevalent in women and young adults.⁸

Heterogeneous in its causes and manifestations

In about 75% of patients with Budd-Chiari syndrome, a hereditary or acquired hematologic abnormality or thrombotic diathesis can be found.^8–10 Some of the major causes are summarized in Table 3. The most common causes are hematologic diseases, especially myeloproliferative disorders.^7,8,11

Budd-Chiari syndrome is also heterogeneous in its manifestations, which depend on the extent of the occlusion, on the acuteness of the obstruction, and on whether venous collateral circulation has developed to decompress the liver sinusoids.^9,12,13 Therefore, on the basis of its clinical manifestations, it can be classified as fulminant, acute, subacute, or chronic.^12–16

The fulminant form presents with hepatic encephalopathy within 8 weeks after the development of jaundice. The subacute form, which is the most common, has a more insidious onset in which hepatic sinusoids are decompressed by portal and hepatic venous collateral circulation. The patient usually presents with abdominal pain, ascites, hepatomegaly, nausea, vomiting, and mild jaundice. Finally the chronic form presents as complications of cirrhosis.^12–16

Imaging plays an important role in diagnosing Budd-Chiari syndrome

Imaging plays an important role in detecting and classifying Budd-Chiari syndrome.

Duplex ultrasonography is useful for detecting this syndrome and has a sensitivity and specificity of 85%.⁹

CT and magnetic resonance imaging can also help in the diagnosis by showing thrombosis, obstruction, or occlusion in the hepatic vein or the inferior vena cava.⁵

Venography is the gold standard for diagnosis. However, it should be performed only if noninvasive tests are negative or nondiagnostic and there is a high clinical suspicion of this disease.¹⁷ Budd-Chiari syndrome has a characteristic pattern on venography known as “spider web,” which is due to the formation of venous collaterals to bypass the occluded hepatic veins.⁹

Liver biopsy is not necessarily required to confirm the diagnosis of Budd-Chiari syndrome, but it can help in diagnosing the acute or subacute forms and also in ruling out other causes. Histologic findings can include centrizonal congestion, loss of hepatocytes, hemorrhage, and fibrosis.^18,19 Regenerative nodules are found in about 25% of patients.¹⁹

 

TREATING BUDD-CHIARI SYNDROME

The primary goal of treatment is to prevent further extension of the venous thrombosis in the hepatic veins, in their collaterals, and in the intrahepatic and extrahepatic portal venous system. Resolution of hepatic congestion improves liver perfusion and preserves function of the hepatocytes.

Anticoagulation is recommended in the early stages. Heparin therapy should be initiated and subsequently switched to warfarin with the goal of achieving an international normalized ratio of the prothrombin time of 2.0 to 2.5.^8,9,19

Thrombolysis is effective in the acute form.^20,21 Recanalization, including percutaneous or transhepatic angioplasty of localized segments of the narrowed hepatic veins or inferior vena cava, has long-term patency rates of 80% to 90%.²²

If thrombolytic therapy and angioplasty are unsuccessful, a transjugular intrahepatic portosystemic shunt or a surgical procedure (side-to-side portocaval shunt, central splenorenal shunt, or mesocaval shunt) should be considered.⁹

Liver transplantation is another treatment option in those with fulminant Budd-Chiari syndrome or advanced liver cirrhosis.⁸

PROGNOSIS HAS IMPROVED

The prognosis of Budd-Chiari syndrome has improved, thanks to both earlier diagnosis and new treatments. The 1-year survival rate, which was about 60% before 1985, has increased to more than 80% in recent cohort studies.¹⁹

Studies have shown that the Child-Pugh score, which is based on a combination of serum albumin, bilirubin, prothrombin time, encephalopathy, and ascites, can be considered as an independent prognostic factor. A lower Child-Pugh score and a younger age are associated with a good prognosis.^19,23,24 (The Child-Pugh score cannot be applied to our patient because he does not have cirrhosis.)

What happened to our patient?

Our patient was started on anticoagulation for his Budd-Chiari syndrome and on bortezomib (Velcade) and dexamethasone for his multiple myeloma. He achieved remarkable improvement in his liver function tests. Follow-up duplex ultrasonography 1 month after discharge revealed that the stenosis in the hepatic veins had resolved. He is following up with the oncology clinic for management of his multiple myeloma.

A 25-year-old man presented to his primary care physician with generalized malaise. His symptoms started around 2 months earlier with progressive fatigue, nausea, decreased appetite, and weight loss (15 lb in 2 months). He denied having fever, chills, night sweats, abdominal pain, diarrhea, melena, or hematochezia.

His medical history was remarkable only for depression, well controlled with sertraline (Zoloft), which he started taking 3 years ago. He was not taking any other prescribed, over-the-counter, or herbal medications.

He had no family history of cancer or liver disease. He did not smoke and rarely drank alcohol. He had never used recreational drugs. He was sexually active with one female partner, used condoms for protection, and had never been diagnosed with a sexually transmitted disease. He had not traveled recently and had not been exposed to any pet.

On physical examination, the patient was alert and oriented. He was afebrile, his heart rate was 90 beats per minute and regular, his respiratory rate was 18 breaths per minute, and his blood pressure was 125/77 mm Hg. Auscultation of the chest was clear. His heart sounds were normal, and there was no murmur, gallop, or rub. His right upper quadrant was mildly tender, and his liver was palpably enlarged. He had no peripheral edema, clubbing, rash, telangiectasia, or other skin changes. Examination of the joints revealed no warmth, swelling, or erythema.

The patient’s laboratory values on admission are shown in Table 1. Of note, his serum alkaline phosphatase level was 1,307 U/L (reference range 40–150 U/L).

LIVER TESTS CAN NARROW THE DIAGNOSIS

The most commonly used laboratory tests of the liver can be classified into those that measure either:

• Liver synthetic function (eg, the serum albumin and bilirubin concentrations and the prothrombin time) or
• Liver damage, as reflected by the serum concentrations of the enzymes alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase, and gamma-glutamyltransferase (GGT).^1,2

ALT and AST are normally concentrated in the hepatocytes and thus, when present in the serum in elevated concentrations, are markers of liver cell injury. The serum levels of these enzymes start to increase within a few hours of liver cell injury as they leak out of the cells via the damaged cell membrane. AST is less liver-specific than ALT, since AST levels can be elevated not only in liver injury but also in muscle, cardiac, and red blood cell injury.^3,4

Alkaline phosphatase is actually a heterogeneous group of enzymes found mainly in liver and bone cells. Hepatic alkaline phosphatase is concentrated near the biliary canalicular membrane of the hepatocyte. Accordingly, increased levels of hepatic alkaline phosphatase are mainly seen in liver diseases that predominantly affect the biliary system.³

GGT is also concentrated in hepatic biliary epithelial cells, and thus GGT elevation is another marker of hepatobiliary disease. In fact, measuring the GGT level can help to determine whether an isolated elevation of alkaline phosphatase is due to liver injury.^2,3

Accordingly, liver diseases can be classified into two broad categories:

• Hepatocellular injury, in which the primary injury occurs to the hepatocytes
• Cholestatic injury, in which the primary injury is to the bile ducts.

In the former, elevated levels of ALT and AST predominate, while in the latter, elevated alkaline phosphatase is the main finding.³

 

WHAT TEST NEXT FOR OUR PATIENT?

1. What is the next most appropriate diagnostic step for our patient?

• Liver biopsy
• Ultrasonography of the liver
• Computed tomography (CT) of the liver
• Observation

Our patient has an elevated GGT level, which suggests that his elevated alkaline phosphatase is of hepatic rather than bony origin. Moreover, a serum alkaline phosphatase level that is elevated out of proportion to the aminotransferase levels reflects cholestatic liver injury.

Cholestatic liver diseases can be classified into two broad categories based on whether the injury affects the microscopic intrahepatic bile ducts (intrahepatic cholestasis) or extrahepatic large bile duct (extrahepatic cholestasis). The simplest diagnostic test to differentiate between the two is ultrasonography, which can identify extrahepatic biliary obstruction fairly well. Therefore, the diagnostic workup of cholestatic liver injury should start with ultrasonography of the liver to differentiate between intrahepatic and extrahepatic processes (Figure 1).

CASE CONTINUED: ULTRASONOGRAPHY IS MOSTLY NORMAL

Ultrasonography of the right upper quadrant revealed that the liver had normal echogenicity and was mildly enlarged. There was no focal hepatic lesion. The gallbladder appeared normal, with no stones or sludge. No dilated intrahepatic or extrahepatic biliary ducts were seen. The common bile duct measured 4 mm. A small amount of ascites not amenable to paracentesis was present.

Thus, in the absence of biliary dilation on ultrasonography, we are dealing with an intrahepatic cholestatic process.

CAUSES OF CHOLESTATIC LIVER DISEASE

Table 2 lists the common causes of cholestatic liver disease.

Viral hepatitis

Viral hepatitis most often produces a hepatocellular pattern of injury (ie, AST and ALT elevations predominate). However, in rare cases it can cause a cholestatic pattern of injury.

Our patient subsequently had serologic tests for viral hepatitis, including hepatitis A, B, and C, and the results were negative.

Autoimmune liver disease

The three most common forms of autoimmune liver disease are autoimmune hepatitis, primary biliary cirrhosis, and primary sclerosing cholangitis.

Autoimmune hepatitis is characterized by high serum ALT and AST levels, whereas primary biliary cirrhosis and primary sclerosing cholangitis are associated with predominant elevations of alkaline phosphatase, since they are cholestatic disorders.

Our patient’s alkaline phosphatase level was much higher than his ALT and AST levels, making the latter two diseases more likely.

Primary biliary cirrhosis (and autoimmune hepatitis) are associated with autoantibodies in the serum, such as antinuclear antibody, smooth muscle antibody, and antimitochondrial antibody.

Our patient subsequently was tested for these antibodies, and the results were negative.

Primary sclerosing cholangitis usually affects the extrahepatic biliary system. Thus, if it is present, abnormalities should be seen on imaging.

As mentioned previously, no dilated intrahepatic or extrahepatic biliary ducts were seen on ultrasonography in our patient. Moreover, primary sclerosing cholangitis is associated with inflammatory bowel disease, particularly ulcerative colitis, which our patient did not have.

Drug-induced liver injury

Drug-induced liver injury is a common cause of cholestatic liver disease. However, our patient was not taking any prescribed, over-the-counter, or herbal medications. Additionally, he denied heavy alcohol use.

Infiltrative disorders

Infiltrative disorders such as amyloidosis, sarcoidosis, or lymphoma should be considered in the differential diagnosis of cholestatic liver disease. A clue to a possible infiltrative process is a markedly elevated level of alkaline phosphatase with a mildly increased serum bilirubin concentration, both of which our patient had.

 

AFTER ULTRASONOGRAPHY, WHAT IS THE NEXT STEP?

2. Which of the following is the next most appropriate diagnostic test for our patient?

• Endoscopic retrograde cholangiopancreatography (ERCP)
• Magnetic resonance cholangiopancreatography (MRCP)
• Liver biopsy
• CT of the abdomen

Figure 1 shows a proposed algorithm for evaluating increased alkaline phosphatase levels.

If there is no biliary duct dilation on ultrasonography, then abnormal levels of alkaline phosphatase most likely represent an intrahepatic pattern of cholestatic liver injury. Therefore, additional imaging with CT or magnetic resonance imaging is of limited diagnostic value. ERCP is used today for therapy rather than diagnosis, so its use is limited to patients known to have dilated biliary ducts on imaging. Liver biopsy, however, can provide useful findings.

Case continued: He undergoes biopsy

Our patient underwent transjugular liver biopsy. During the procedure, transjugular venography showed stenosis in the right, middle, and left hepatic veins and the hepatic portion of the inferior vena cava, consistent with Budd-Chiari syndrome.

The liver biopsy specimen was positive for extensive deposition of slight eosinophilic and amorphous material in a sinusoidal pattern in the liver parenchyma, as well as in the portal tracts, with markedly atrophic hepatocytes. Congo red birefringence confirmed the diagnosis of amyloidosis. The immunohistochemical phenotype was positive for kappa light chains, which is diagnostic for primary-type amyloidosis, also called amyloidosis of light chain composition, or AL.

Bone marrow aspiration and bone marrow biopsy were performed and showed 22% plasma cells, well above the normal range (0–2%), consistent with the diagnosis of multiple myeloma.

BUDD-CHIARI SYNDROME: A CHALLENGING DIAGNOSIS

Budd-Chiari syndrome is a rare condition characterized by obstruction of venous outflow from the liver at a site that may vary from the small hepatic veins up to the inferior vena cava or even the right atrium.^5,6 Obstruction of hepatic venous outflow leads to sinusoidal congestion and hypoxic damage of the hepatocytes.⁷ Hypoxia and necrosis of the hepatocytes result in the release of free radicals. Cirrhosis can eventually occur secondary to ischemic necrosis of hepatocytes and hepatic fibrosis.⁸

The estimated incidence of this syndrome is 1 in 2.5 million persons per year.⁷ It is more prevalent in women and young adults.⁸

Heterogeneous in its causes and manifestations

In about 75% of patients with Budd-Chiari syndrome, a hereditary or acquired hematologic abnormality or thrombotic diathesis can be found.^8–10 Some of the major causes are summarized in Table 3. The most common causes are hematologic diseases, especially myeloproliferative disorders.^7,8,11

Budd-Chiari syndrome is also heterogeneous in its manifestations, which depend on the extent of the occlusion, on the acuteness of the obstruction, and on whether venous collateral circulation has developed to decompress the liver sinusoids.^9,12,13 Therefore, on the basis of its clinical manifestations, it can be classified as fulminant, acute, subacute, or chronic.^12–16

The fulminant form presents with hepatic encephalopathy within 8 weeks after the development of jaundice. The subacute form, which is the most common, has a more insidious onset in which hepatic sinusoids are decompressed by portal and hepatic venous collateral circulation. The patient usually presents with abdominal pain, ascites, hepatomegaly, nausea, vomiting, and mild jaundice. Finally the chronic form presents as complications of cirrhosis.^12–16

Imaging plays an important role in diagnosing Budd-Chiari syndrome

Imaging plays an important role in detecting and classifying Budd-Chiari syndrome.

Duplex ultrasonography is useful for detecting this syndrome and has a sensitivity and specificity of 85%.⁹

CT and magnetic resonance imaging can also help in the diagnosis by showing thrombosis, obstruction, or occlusion in the hepatic vein or the inferior vena cava.⁵

Venography is the gold standard for diagnosis. However, it should be performed only if noninvasive tests are negative or nondiagnostic and there is a high clinical suspicion of this disease.¹⁷ Budd-Chiari syndrome has a characteristic pattern on venography known as “spider web,” which is due to the formation of venous collaterals to bypass the occluded hepatic veins.⁹

Liver biopsy is not necessarily required to confirm the diagnosis of Budd-Chiari syndrome, but it can help in diagnosing the acute or subacute forms and also in ruling out other causes. Histologic findings can include centrizonal congestion, loss of hepatocytes, hemorrhage, and fibrosis.^18,19 Regenerative nodules are found in about 25% of patients.¹⁹

 

TREATING BUDD-CHIARI SYNDROME

The primary goal of treatment is to prevent further extension of the venous thrombosis in the hepatic veins, in their collaterals, and in the intrahepatic and extrahepatic portal venous system. Resolution of hepatic congestion improves liver perfusion and preserves function of the hepatocytes.

Anticoagulation is recommended in the early stages. Heparin therapy should be initiated and subsequently switched to warfarin with the goal of achieving an international normalized ratio of the prothrombin time of 2.0 to 2.5.^8,9,19

Thrombolysis is effective in the acute form.^20,21 Recanalization, including percutaneous or transhepatic angioplasty of localized segments of the narrowed hepatic veins or inferior vena cava, has long-term patency rates of 80% to 90%.²²

If thrombolytic therapy and angioplasty are unsuccessful, a transjugular intrahepatic portosystemic shunt or a surgical procedure (side-to-side portocaval shunt, central splenorenal shunt, or mesocaval shunt) should be considered.⁹

Liver transplantation is another treatment option in those with fulminant Budd-Chiari syndrome or advanced liver cirrhosis.⁸

PROGNOSIS HAS IMPROVED

The prognosis of Budd-Chiari syndrome has improved, thanks to both earlier diagnosis and new treatments. The 1-year survival rate, which was about 60% before 1985, has increased to more than 80% in recent cohort studies.¹⁹

Studies have shown that the Child-Pugh score, which is based on a combination of serum albumin, bilirubin, prothrombin time, encephalopathy, and ascites, can be considered as an independent prognostic factor. A lower Child-Pugh score and a younger age are associated with a good prognosis.^19,23,24 (The Child-Pugh score cannot be applied to our patient because he does not have cirrhosis.)

What happened to our patient?

Our patient was started on anticoagulation for his Budd-Chiari syndrome and on bortezomib (Velcade) and dexamethasone for his multiple myeloma. He achieved remarkable improvement in his liver function tests. Follow-up duplex ultrasonography 1 month after discharge revealed that the stenosis in the hepatic veins had resolved. He is following up with the oncology clinic for management of his multiple myeloma.