Richard McClain, MD

To the Editor:

A 71-year-old man presented with a nodule on the vertex of the scalp of 1 year’s duration. The lesion had become soft and tender during the week prior to presentation. He noted that he was experiencing headaches and a buzzing sound in his head. He denied all other neurologic symptoms. The patient was given amoxicillin from a primary care physician and was referred to our institution for evaluation of a presumed inflamed cyst.

The patient’s medical history included an intracranial arteriovenous fistula (AVF) treated with endovascular embolization 1 year prior to presentation, 2 substantial falls in childhood with head trauma and loss of consciousness, essential hypertension, and an aortic aneurysm. His medications included amlodipine, lisinopril, amoxicillin, a multivitamin, and grape seed extract.

Physical examination revealed a 2-cm, pink, somewhat rubbery, subcutaneous, nonmobile nodule on the vertex of the scalp (Figure 1). The lesion was not consistent with a common pilar cyst, and an excisional biopsy was performed to exclude malignancy. Upon superficial incision, the lesion bled moderately, and the procedure was immediately discontinued. Hemostasis was obtained, and the patient was sent for ultrasonography of the lesion.

Ultrasonography demonstrated a small hypoechoic nodule measuring up to 0.5 cm containing a tangle of vessels in the subcutaneous soft tissue corresponding to the palpable abnormality. A cerebral angiogram demonstrated a dural AVF of the superior sagittal sinus with multifocal supply that connected with this scalp nodule (Figure 2). The patient was treated by interventional neuroradiology with endovascular embolization, which resulted in complete resolution of the scalp nodule.

Scalp arteriovenous fistulas (S-AVFs) are characterized by abnormal connections between supplying arteries and draining veins in the subcutaneous plane of the scalp.^1,2 The veins of an S-AVF undergo progressive aneurysmal dilatation from abnormal hemodynamics.^1-3 Scalp arteriovenous fistulas are rare and may present as either an innocuous-looking scalp nodule or a progressively enlarging pulsatile mass on the scalp.^2-4 Associated symptoms often include headache, local pain, bruits, tinnitus, and thrill.^1,3,4 Recurrent hemorrhage, scalp necrosis, congestive heart failure, epilepsy, mental retardation, and intracranial ischemia also may occur.⁴

Scalp AVFs may occur with or without intracranial communication.⁴ Spontaneous S-AVFs with intracranial communication are uncommon, and their etiology is unclear. They may form as congenital malformations or may be idiopathic. Factors increasing circulation through the S-AVF such as trauma, pregnancy, hormonal changes, and inflammation prompt the development of symptoms.⁴ Scalp AVFs also may be caused by trauma.³ Scalp AVFs without intracranial communication have been reported following hair transplantation.¹ Scalp AVFs with intracranial communication have been reported months to years after skull fracture or craniotomy.² True spontaneous S-AVFs are difficult to differentiate from traumatic S-AVFs other than by history alone.²

Increased venous pressure has been shown to generate AVFs in rats.⁵ It has been suggested that S-AVFs can become enlarged by capturing subcutaneous or intracranial feeder vessels and that the consequent hemodynamic stress may induce de novo aneurysms in S-AVFs. Additionally, intracranial AVFs may alter the intracranial hemodynamics, leading to increased venous pressure in the superior sagittal sinus and the formation of communicating S-AVFs.⁵ Interestingly, our patient had an intracranial AVF treated with endovascular embolization 1 year prior to the formation of the S-AVF. An angiogram at the time of this embolization procedure did not demonstrate any S-AVFs. Furthermore, our patient has a history of 2 substantial falls in childhood with head trauma and loss of consciousness. Perhaps these traumas initiated a channel through the cranium where an S-AVF with intracranial communication was able to form and may have only become clinically or radiographically detectable once it enlarged due to the altered hemodynamics caused by the intracranial AVF 1 year prior.

The diagnosis of an S-AVF is confirmed with imaging studies. Doppler ultrasonography initially will help to detect that a lesion is vascular in nature. Intra-arterial digital subtraction angiography is the gold-standard imaging technique and is necessary to delineate the feeding arteries and the draining channels as well as possible communication with intracranial vasculature.^1,2 There is controversy regarding the appropriate treatment of S-AVFs.² Each S-AVF possesses unique anatomic features that dictate appropriate management. The prognosis for an S-AVF is extremely variable, and the decision to treat is based on the patient’s symptoms and risk for exsanguinating hemorrhage.^2,4 Neurosurgical approaches include ligation of the feeding arteries, surgical resection, electrothrombosis, direct intralesional injection of sclerosing agents, and endovascular embolization. Endovascular intervention increasingly is utilized as a primary treatment or as a preoperative adjunct to surgery.^2,4 Large S-AVFs have a high risk for recurrence after treatment with endovascular embolization alone. In cases with intracranial communication, the intracranial component is treated first.²

This case emphasizes the importance of including S-AVFs on the dermatologic differential diagnosis of a scalp nodule, especially in patients with any history of intracranial AVF. A thorough history, detailed intake of potential signs and symptoms of AVF, and palpation for bruits is recommended as part of the surgical evaluation of a scalp nodule. Imaging of scalp nodules also should be considered for patients with any history of intracranial AVF; S-AVFs should be referred to neurosurgery or interventional neuroradiology for evaluation and possible treatment.

To the Editor:

A 71-year-old man presented with a nodule on the vertex of the scalp of 1 year’s duration. The lesion had become soft and tender during the week prior to presentation. He noted that he was experiencing headaches and a buzzing sound in his head. He denied all other neurologic symptoms. The patient was given amoxicillin from a primary care physician and was referred to our institution for evaluation of a presumed inflamed cyst.

The patient’s medical history included an intracranial arteriovenous fistula (AVF) treated with endovascular embolization 1 year prior to presentation, 2 substantial falls in childhood with head trauma and loss of consciousness, essential hypertension, and an aortic aneurysm. His medications included amlodipine, lisinopril, amoxicillin, a multivitamin, and grape seed extract.

Physical examination revealed a 2-cm, pink, somewhat rubbery, subcutaneous, nonmobile nodule on the vertex of the scalp (Figure 1). The lesion was not consistent with a common pilar cyst, and an excisional biopsy was performed to exclude malignancy. Upon superficial incision, the lesion bled moderately, and the procedure was immediately discontinued. Hemostasis was obtained, and the patient was sent for ultrasonography of the lesion.

Ultrasonography demonstrated a small hypoechoic nodule measuring up to 0.5 cm containing a tangle of vessels in the subcutaneous soft tissue corresponding to the palpable abnormality. A cerebral angiogram demonstrated a dural AVF of the superior sagittal sinus with multifocal supply that connected with this scalp nodule (Figure 2). The patient was treated by interventional neuroradiology with endovascular embolization, which resulted in complete resolution of the scalp nodule.

Scalp arteriovenous fistulas (S-AVFs) are characterized by abnormal connections between supplying arteries and draining veins in the subcutaneous plane of the scalp.^1,2 The veins of an S-AVF undergo progressive aneurysmal dilatation from abnormal hemodynamics.^1-3 Scalp arteriovenous fistulas are rare and may present as either an innocuous-looking scalp nodule or a progressively enlarging pulsatile mass on the scalp.^2-4 Associated symptoms often include headache, local pain, bruits, tinnitus, and thrill.^1,3,4 Recurrent hemorrhage, scalp necrosis, congestive heart failure, epilepsy, mental retardation, and intracranial ischemia also may occur.⁴

Scalp AVFs may occur with or without intracranial communication.⁴ Spontaneous S-AVFs with intracranial communication are uncommon, and their etiology is unclear. They may form as congenital malformations or may be idiopathic. Factors increasing circulation through the S-AVF such as trauma, pregnancy, hormonal changes, and inflammation prompt the development of symptoms.⁴ Scalp AVFs also may be caused by trauma.³ Scalp AVFs without intracranial communication have been reported following hair transplantation.¹ Scalp AVFs with intracranial communication have been reported months to years after skull fracture or craniotomy.² True spontaneous S-AVFs are difficult to differentiate from traumatic S-AVFs other than by history alone.²

Increased venous pressure has been shown to generate AVFs in rats.⁵ It has been suggested that S-AVFs can become enlarged by capturing subcutaneous or intracranial feeder vessels and that the consequent hemodynamic stress may induce de novo aneurysms in S-AVFs. Additionally, intracranial AVFs may alter the intracranial hemodynamics, leading to increased venous pressure in the superior sagittal sinus and the formation of communicating S-AVFs.⁵ Interestingly, our patient had an intracranial AVF treated with endovascular embolization 1 year prior to the formation of the S-AVF. An angiogram at the time of this embolization procedure did not demonstrate any S-AVFs. Furthermore, our patient has a history of 2 substantial falls in childhood with head trauma and loss of consciousness. Perhaps these traumas initiated a channel through the cranium where an S-AVF with intracranial communication was able to form and may have only become clinically or radiographically detectable once it enlarged due to the altered hemodynamics caused by the intracranial AVF 1 year prior.

The diagnosis of an S-AVF is confirmed with imaging studies. Doppler ultrasonography initially will help to detect that a lesion is vascular in nature. Intra-arterial digital subtraction angiography is the gold-standard imaging technique and is necessary to delineate the feeding arteries and the draining channels as well as possible communication with intracranial vasculature.^1,2 There is controversy regarding the appropriate treatment of S-AVFs.² Each S-AVF possesses unique anatomic features that dictate appropriate management. The prognosis for an S-AVF is extremely variable, and the decision to treat is based on the patient’s symptoms and risk for exsanguinating hemorrhage.^2,4 Neurosurgical approaches include ligation of the feeding arteries, surgical resection, electrothrombosis, direct intralesional injection of sclerosing agents, and endovascular embolization. Endovascular intervention increasingly is utilized as a primary treatment or as a preoperative adjunct to surgery.^2,4 Large S-AVFs have a high risk for recurrence after treatment with endovascular embolization alone. In cases with intracranial communication, the intracranial component is treated first.²

This case emphasizes the importance of including S-AVFs on the dermatologic differential diagnosis of a scalp nodule, especially in patients with any history of intracranial AVF. A thorough history, detailed intake of potential signs and symptoms of AVF, and palpation for bruits is recommended as part of the surgical evaluation of a scalp nodule. Imaging of scalp nodules also should be considered for patients with any history of intracranial AVF; S-AVFs should be referred to neurosurgery or interventional neuroradiology for evaluation and possible treatment.

To the Editor:

A 71-year-old man presented with a nodule on the vertex of the scalp of 1 year’s duration. The lesion had become soft and tender during the week prior to presentation. He noted that he was experiencing headaches and a buzzing sound in his head. He denied all other neurologic symptoms. The patient was given amoxicillin from a primary care physician and was referred to our institution for evaluation of a presumed inflamed cyst.

The patient’s medical history included an intracranial arteriovenous fistula (AVF) treated with endovascular embolization 1 year prior to presentation, 2 substantial falls in childhood with head trauma and loss of consciousness, essential hypertension, and an aortic aneurysm. His medications included amlodipine, lisinopril, amoxicillin, a multivitamin, and grape seed extract.

Physical examination revealed a 2-cm, pink, somewhat rubbery, subcutaneous, nonmobile nodule on the vertex of the scalp (Figure 1). The lesion was not consistent with a common pilar cyst, and an excisional biopsy was performed to exclude malignancy. Upon superficial incision, the lesion bled moderately, and the procedure was immediately discontinued. Hemostasis was obtained, and the patient was sent for ultrasonography of the lesion.

Ultrasonography demonstrated a small hypoechoic nodule measuring up to 0.5 cm containing a tangle of vessels in the subcutaneous soft tissue corresponding to the palpable abnormality. A cerebral angiogram demonstrated a dural AVF of the superior sagittal sinus with multifocal supply that connected with this scalp nodule (Figure 2). The patient was treated by interventional neuroradiology with endovascular embolization, which resulted in complete resolution of the scalp nodule.

Scalp arteriovenous fistulas (S-AVFs) are characterized by abnormal connections between supplying arteries and draining veins in the subcutaneous plane of the scalp.^1,2 The veins of an S-AVF undergo progressive aneurysmal dilatation from abnormal hemodynamics.^1-3 Scalp arteriovenous fistulas are rare and may present as either an innocuous-looking scalp nodule or a progressively enlarging pulsatile mass on the scalp.^2-4 Associated symptoms often include headache, local pain, bruits, tinnitus, and thrill.^1,3,4 Recurrent hemorrhage, scalp necrosis, congestive heart failure, epilepsy, mental retardation, and intracranial ischemia also may occur.⁴

Scalp AVFs may occur with or without intracranial communication.⁴ Spontaneous S-AVFs with intracranial communication are uncommon, and their etiology is unclear. They may form as congenital malformations or may be idiopathic. Factors increasing circulation through the S-AVF such as trauma, pregnancy, hormonal changes, and inflammation prompt the development of symptoms.⁴ Scalp AVFs also may be caused by trauma.³ Scalp AVFs without intracranial communication have been reported following hair transplantation.¹ Scalp AVFs with intracranial communication have been reported months to years after skull fracture or craniotomy.² True spontaneous S-AVFs are difficult to differentiate from traumatic S-AVFs other than by history alone.²

Increased venous pressure has been shown to generate AVFs in rats.⁵ It has been suggested that S-AVFs can become enlarged by capturing subcutaneous or intracranial feeder vessels and that the consequent hemodynamic stress may induce de novo aneurysms in S-AVFs. Additionally, intracranial AVFs may alter the intracranial hemodynamics, leading to increased venous pressure in the superior sagittal sinus and the formation of communicating S-AVFs.⁵ Interestingly, our patient had an intracranial AVF treated with endovascular embolization 1 year prior to the formation of the S-AVF. An angiogram at the time of this embolization procedure did not demonstrate any S-AVFs. Furthermore, our patient has a history of 2 substantial falls in childhood with head trauma and loss of consciousness. Perhaps these traumas initiated a channel through the cranium where an S-AVF with intracranial communication was able to form and may have only become clinically or radiographically detectable once it enlarged due to the altered hemodynamics caused by the intracranial AVF 1 year prior.

The diagnosis of an S-AVF is confirmed with imaging studies. Doppler ultrasonography initially will help to detect that a lesion is vascular in nature. Intra-arterial digital subtraction angiography is the gold-standard imaging technique and is necessary to delineate the feeding arteries and the draining channels as well as possible communication with intracranial vasculature.^1,2 There is controversy regarding the appropriate treatment of S-AVFs.² Each S-AVF possesses unique anatomic features that dictate appropriate management. The prognosis for an S-AVF is extremely variable, and the decision to treat is based on the patient’s symptoms and risk for exsanguinating hemorrhage.^2,4 Neurosurgical approaches include ligation of the feeding arteries, surgical resection, electrothrombosis, direct intralesional injection of sclerosing agents, and endovascular embolization. Endovascular intervention increasingly is utilized as a primary treatment or as a preoperative adjunct to surgery.^2,4 Large S-AVFs have a high risk for recurrence after treatment with endovascular embolization alone. In cases with intracranial communication, the intracranial component is treated first.²

This case emphasizes the importance of including S-AVFs on the dermatologic differential diagnosis of a scalp nodule, especially in patients with any history of intracranial AVF. A thorough history, detailed intake of potential signs and symptoms of AVF, and palpation for bruits is recommended as part of the surgical evaluation of a scalp nodule. Imaging of scalp nodules also should be considered for patients with any history of intracranial AVF; S-AVFs should be referred to neurosurgery or interventional neuroradiology for evaluation and possible treatment.

 

Case Reports

Patient 1
A 56-year-old white man with a history of hypertension, hyperlipidemia, sleep apnea, bilateral knee replacement, and cataract removal presented to the emergency department with a worsening rash on the left posterior medial leg of 6 months’ duration. He reported associated redness and tenderness with the plaques as well as increased swelling and firmness of the leg. He was admitted to the hospital where the infectious disease team treated him with cefazolin for presumed cellulitis. His condition did not improve, and another course of cefazolin was started in addition to oral fluconazole and clotrimazole–betamethasone dipropionate lotion for a possible fungal cause. Again, treatment provided no improvement.

He was then evaluated by dermatology. On physical examination, the patient had edema, warmth, and induration of the left lower leg. There also was an annular and serpiginous indurated plaque with minimal scale on the left lower leg (Figure 1). A firm, dark red to purple plaque on the left medial thigh with mild scale was present. There also was scaling of the right plantar foot.

Skin biopsy revealed a dermal capillary proliferation with a scattering of inflammatory cells including eosinophils as well as dermal fibrosis (Figure 2). Periodic acid–Schiff and human herpesvirus 8 (HHV-8) immunostains were negative. Considering the degree and depth of vascular proliferation, Mali-type acroangiodermatitis (AAD) was the favored diagnosis.

Patient 2
A 72-year-old white man presented with a firm asymptomatic growth on the left dorsal forearm of 3 months’ duration. It was located near the site of a prior squamous cell carcinoma that was excised 1 year prior to presentation. The patient had no treatment or biopsy of the presenting lesion. His medical and surgical history included polycystic kidney disease and renal transplantation 4 years prior to presentation. He also had an arteriovenous fistula of the left arm. His other chronic diseases included chronic obstructive lung disease, congestive heart failure, hypertension, type 2 diabetes mellitus, and obstructive sleep apnea.

On physical examination, the patient had a 1-cm violaceous nodule on the extensor surface of the left mid forearm. An arteriovenous fistula was present proximal to the lesion on the left arm (Figure 3).

Skin biopsy revealed a tightly packed proliferation of small vascular channels that tested negative for HHV-8, tumor protein p63, and cytokeratin 5/6. Erythrocytes were noted in the lumen of some of these vessels. Neutrophils were scattered and clustered throughout the specimen (Figure 4A). Blood vessels were highlighted with CD34 (Figure 4B). Grocott-Gomori methenamine-silver stain was negative for infectious agents. These findings favored AAD secondary to an arteriovenous malformation, consistent with Stewart-Bluefarb syndrome (SBS).

 

Comment

Presentation of AAD
Acroangiodermatitis is a rare chronic inflammatory skin process involving a reactive proliferation of capillaries and fibrosis of the skin that resembles Kaposi sarcoma both clinically and histopathologically. The condition has been reported in patients with chronic venous insufficiency,¹ congenital arteriovenous malformation,² acquired iatrogenic arteriovenous fistula,³ paralyzed extremity,⁴ suction socket lower limb prosthesis (amputees),⁵ and minor trauma.^6-8 The lesions of AAD tend to be circumscribed, slowly evolving, red-violaceous (or brown or dusky) macules, papules, or plaques that may become verrucous or develop into painful ulcerations. They generally occur on the distal dorsal aspects of the lower legs and feet.¹¹⁰

Variants of AAD
Mali et al⁹ first reported cutaneous manifestations resembling Kaposi sarcoma in 18 patients with chronic venous insufficiency in 1965. Two years later, Bluefarb and Adams¹⁰ described kaposiform skin lesions in one patient with a congenital arteriovenous malformation without chronic venous insufficiency. It was not until 1974, however, that Earhart et al¹¹ proposed the term pseudo-Kaposi sarcoma.^10,11 Based on these findings, AAD is described as 2 variants: Mali type and SBS.

Mali-type AAD is more common and typically occurs in elderly men. It classically presents bilaterally on the lower extremities in association with severe chronic venous insufficiency.⁵ Skin lesions usually occur on the medial aspect of the lower legs (as in patient 1), dorsum of the heel, hallux, or second toe.¹²

The etiology of Mali-type AAD is poorly understood. The leading theory is that the condition involves reduced perfusion due to chronic edema, resulting in neovascularization, fibroblast proliferation, hypertrophy, and inflammatory skin changes. When AAD occurs in the setting of a suction socket prosthesis, the negative pressure of the stump-socket environment is thought to alter local circulation, leading to proliferation of small blood vessels.^5,13

Stewart-Bluefarb syndrome usually involves a single extremity in young adults with congenital arteriovenous malformations, amputees, and individuals with hemiplegia or iatrogenic arteriovenous fistulae (as in patient 2).¹ It was once thought to occur secondary to Klippel-Trenaunay-Weber syndrome; however, SBS rarely is accompanied by limb hypertrophy.⁹ Pathogenesis is thought to involve an angiogenic response to a high perfusion rate and high oxygen saturation, which leads to fibroblast proliferation and reactive endothelial hyperplasia.^1,14

Diagnosis and Differential Diagnosis
Prompt identification of an underlying arteriovenous anomaly is critical, given the sequelae of high-flow shunts, which may result in skin ulceration, limb length discrepancy, cortical thinning of bone with regional osteoporosis, and congestive heart failure.^1,5 Duplex ultrasonography is the first-line diagnostic modality because it is noninvasive and widely available. The key doppler feature of an arteriovenous malformation is low resistance and high diastolic pulsatile flow,¹ which should be confirmed with magnetic resonance angiography or computed tomography angiography if present on ultrasonography.

The differential diagnosis of AAD includes Kaposi sarcoma, reactive angioendotheliomatosis, diffuse dermal angiomatosis, intravascular histiocytosis, glomeruloid angioendotheliomatosis, and angiopericytomatosis.^15,16 These entities present as multiple erythematous, violaceous, purpuric patches and plaques generally on the extremities but can have a widely varied distribution. Some lesions evolve to necrosis or ulceration. Histopathologic analysis is useful to differentiate these entities.

Histopathology
The histopathologic features of AAD can be nonspecific; clinicopathologic correlation often is necessary to establish the diagnosis. Features include a proliferation of small thick-walled vessels, often in a lobular arrangement, in an edematous papillary dermis. Small thrombi may be observed. There may be increased fibroblasts; plump endothelial cells; a superficial mixed infiltrate comprised of lymphocytes, histiocytes, and eosinophils; and deposition of hemosiderin.^2,5 These characteristics overlap with features of Kaposi sarcoma; AAD, however, lacks slitlike vascular spaces, perivascular CD34⁺ expression, and nuclear atypia. A negative HHV-8 stain will assist in ruling out Kaposi sarcoma.^1,17

Management
Treatment reports are anecdotal. The goal is to correct underlying venous hypertension. Conservative measures with compression garments, intermittent pneumatic compression, and limb elevation are first line.¹⁸ Oral antibiotics and local wound care with topical emollients and corticosteroids have been shown to be effective treatments.^19-21

Oral erythromycin 500 mg 4 times daily for 3 weeks and clobetasol propionate cream 0.05% healed a lower extremity ulcer in a patient with Mali-type AAD.²¹ In another patient, conservative treatment of Mali-type AAD failed, but rapid improvement of 2 lower extremity ulcers resulted after 3 weeks of oral dapsone 50 mg twice daily.²²

A tissue matrix–protective agent (a heparan sulfate mimetic) was reported to completely resolve a patient’s lower extremity ulcer secondary to SBS after other treatment modalities failed.¹⁹ In the SBS variant of AAD, treatment should be directed toward obliterating the underlying arteriovenous malformation, which can be achieved by selective embolization, endovenous ablation, sclerotherapy, or surgical intervention.^1,2

Conclusion

Acroangiodermatitis is a rare entity that is characterized by erythematous violaceous papules and plaques of the extremities, commonly in the setting of chronic venous insufficiency or an arteriovenous shunt. Histopathologic analysis shows proliferation of capillaries with fibrosis, extravasation of erythrocytes, and deposition of hemosiderin without the spindle cells and slitlike vascular spaces characteristic of Kaposi sarcoma. Detection of an underlying arteriovenous malformation is essential, as the disease can have local and systemic consequences, such as skin ulceration and congestive heart failure.¹ Treatment options are conservative, directed toward local wound care, compression, and management of complications, such as ulceration and infection, as well as obliterating any underlying arteriovenous malformation.

 

Case Reports

Patient 1
A 56-year-old white man with a history of hypertension, hyperlipidemia, sleep apnea, bilateral knee replacement, and cataract removal presented to the emergency department with a worsening rash on the left posterior medial leg of 6 months’ duration. He reported associated redness and tenderness with the plaques as well as increased swelling and firmness of the leg. He was admitted to the hospital where the infectious disease team treated him with cefazolin for presumed cellulitis. His condition did not improve, and another course of cefazolin was started in addition to oral fluconazole and clotrimazole–betamethasone dipropionate lotion for a possible fungal cause. Again, treatment provided no improvement.

He was then evaluated by dermatology. On physical examination, the patient had edema, warmth, and induration of the left lower leg. There also was an annular and serpiginous indurated plaque with minimal scale on the left lower leg (Figure 1). A firm, dark red to purple plaque on the left medial thigh with mild scale was present. There also was scaling of the right plantar foot.

Skin biopsy revealed a dermal capillary proliferation with a scattering of inflammatory cells including eosinophils as well as dermal fibrosis (Figure 2). Periodic acid–Schiff and human herpesvirus 8 (HHV-8) immunostains were negative. Considering the degree and depth of vascular proliferation, Mali-type acroangiodermatitis (AAD) was the favored diagnosis.

Patient 2
A 72-year-old white man presented with a firm asymptomatic growth on the left dorsal forearm of 3 months’ duration. It was located near the site of a prior squamous cell carcinoma that was excised 1 year prior to presentation. The patient had no treatment or biopsy of the presenting lesion. His medical and surgical history included polycystic kidney disease and renal transplantation 4 years prior to presentation. He also had an arteriovenous fistula of the left arm. His other chronic diseases included chronic obstructive lung disease, congestive heart failure, hypertension, type 2 diabetes mellitus, and obstructive sleep apnea.

On physical examination, the patient had a 1-cm violaceous nodule on the extensor surface of the left mid forearm. An arteriovenous fistula was present proximal to the lesion on the left arm (Figure 3).

Skin biopsy revealed a tightly packed proliferation of small vascular channels that tested negative for HHV-8, tumor protein p63, and cytokeratin 5/6. Erythrocytes were noted in the lumen of some of these vessels. Neutrophils were scattered and clustered throughout the specimen (Figure 4A). Blood vessels were highlighted with CD34 (Figure 4B). Grocott-Gomori methenamine-silver stain was negative for infectious agents. These findings favored AAD secondary to an arteriovenous malformation, consistent with Stewart-Bluefarb syndrome (SBS).

 

Comment

Presentation of AAD
Acroangiodermatitis is a rare chronic inflammatory skin process involving a reactive proliferation of capillaries and fibrosis of the skin that resembles Kaposi sarcoma both clinically and histopathologically. The condition has been reported in patients with chronic venous insufficiency,¹ congenital arteriovenous malformation,² acquired iatrogenic arteriovenous fistula,³ paralyzed extremity,⁴ suction socket lower limb prosthesis (amputees),⁵ and minor trauma.^6-8 The lesions of AAD tend to be circumscribed, slowly evolving, red-violaceous (or brown or dusky) macules, papules, or plaques that may become verrucous or develop into painful ulcerations. They generally occur on the distal dorsal aspects of the lower legs and feet.¹¹⁰

Variants of AAD
Mali et al⁹ first reported cutaneous manifestations resembling Kaposi sarcoma in 18 patients with chronic venous insufficiency in 1965. Two years later, Bluefarb and Adams¹⁰ described kaposiform skin lesions in one patient with a congenital arteriovenous malformation without chronic venous insufficiency. It was not until 1974, however, that Earhart et al¹¹ proposed the term pseudo-Kaposi sarcoma.^10,11 Based on these findings, AAD is described as 2 variants: Mali type and SBS.

Mali-type AAD is more common and typically occurs in elderly men. It classically presents bilaterally on the lower extremities in association with severe chronic venous insufficiency.⁵ Skin lesions usually occur on the medial aspect of the lower legs (as in patient 1), dorsum of the heel, hallux, or second toe.¹²

The etiology of Mali-type AAD is poorly understood. The leading theory is that the condition involves reduced perfusion due to chronic edema, resulting in neovascularization, fibroblast proliferation, hypertrophy, and inflammatory skin changes. When AAD occurs in the setting of a suction socket prosthesis, the negative pressure of the stump-socket environment is thought to alter local circulation, leading to proliferation of small blood vessels.^5,13

Stewart-Bluefarb syndrome usually involves a single extremity in young adults with congenital arteriovenous malformations, amputees, and individuals with hemiplegia or iatrogenic arteriovenous fistulae (as in patient 2).¹ It was once thought to occur secondary to Klippel-Trenaunay-Weber syndrome; however, SBS rarely is accompanied by limb hypertrophy.⁹ Pathogenesis is thought to involve an angiogenic response to a high perfusion rate and high oxygen saturation, which leads to fibroblast proliferation and reactive endothelial hyperplasia.^1,14

Diagnosis and Differential Diagnosis
Prompt identification of an underlying arteriovenous anomaly is critical, given the sequelae of high-flow shunts, which may result in skin ulceration, limb length discrepancy, cortical thinning of bone with regional osteoporosis, and congestive heart failure.^1,5 Duplex ultrasonography is the first-line diagnostic modality because it is noninvasive and widely available. The key doppler feature of an arteriovenous malformation is low resistance and high diastolic pulsatile flow,¹ which should be confirmed with magnetic resonance angiography or computed tomography angiography if present on ultrasonography.

The differential diagnosis of AAD includes Kaposi sarcoma, reactive angioendotheliomatosis, diffuse dermal angiomatosis, intravascular histiocytosis, glomeruloid angioendotheliomatosis, and angiopericytomatosis.^15,16 These entities present as multiple erythematous, violaceous, purpuric patches and plaques generally on the extremities but can have a widely varied distribution. Some lesions evolve to necrosis or ulceration. Histopathologic analysis is useful to differentiate these entities.

Histopathology
The histopathologic features of AAD can be nonspecific; clinicopathologic correlation often is necessary to establish the diagnosis. Features include a proliferation of small thick-walled vessels, often in a lobular arrangement, in an edematous papillary dermis. Small thrombi may be observed. There may be increased fibroblasts; plump endothelial cells; a superficial mixed infiltrate comprised of lymphocytes, histiocytes, and eosinophils; and deposition of hemosiderin.^2,5 These characteristics overlap with features of Kaposi sarcoma; AAD, however, lacks slitlike vascular spaces, perivascular CD34⁺ expression, and nuclear atypia. A negative HHV-8 stain will assist in ruling out Kaposi sarcoma.^1,17

Management
Treatment reports are anecdotal. The goal is to correct underlying venous hypertension. Conservative measures with compression garments, intermittent pneumatic compression, and limb elevation are first line.¹⁸ Oral antibiotics and local wound care with topical emollients and corticosteroids have been shown to be effective treatments.^19-21

Oral erythromycin 500 mg 4 times daily for 3 weeks and clobetasol propionate cream 0.05% healed a lower extremity ulcer in a patient with Mali-type AAD.²¹ In another patient, conservative treatment of Mali-type AAD failed, but rapid improvement of 2 lower extremity ulcers resulted after 3 weeks of oral dapsone 50 mg twice daily.²²

A tissue matrix–protective agent (a heparan sulfate mimetic) was reported to completely resolve a patient’s lower extremity ulcer secondary to SBS after other treatment modalities failed.¹⁹ In the SBS variant of AAD, treatment should be directed toward obliterating the underlying arteriovenous malformation, which can be achieved by selective embolization, endovenous ablation, sclerotherapy, or surgical intervention.^1,2

Conclusion

Acroangiodermatitis is a rare entity that is characterized by erythematous violaceous papules and plaques of the extremities, commonly in the setting of chronic venous insufficiency or an arteriovenous shunt. Histopathologic analysis shows proliferation of capillaries with fibrosis, extravasation of erythrocytes, and deposition of hemosiderin without the spindle cells and slitlike vascular spaces characteristic of Kaposi sarcoma. Detection of an underlying arteriovenous malformation is essential, as the disease can have local and systemic consequences, such as skin ulceration and congestive heart failure.¹ Treatment options are conservative, directed toward local wound care, compression, and management of complications, such as ulceration and infection, as well as obliterating any underlying arteriovenous malformation.

 

Case Reports

Patient 1
A 56-year-old white man with a history of hypertension, hyperlipidemia, sleep apnea, bilateral knee replacement, and cataract removal presented to the emergency department with a worsening rash on the left posterior medial leg of 6 months’ duration. He reported associated redness and tenderness with the plaques as well as increased swelling and firmness of the leg. He was admitted to the hospital where the infectious disease team treated him with cefazolin for presumed cellulitis. His condition did not improve, and another course of cefazolin was started in addition to oral fluconazole and clotrimazole–betamethasone dipropionate lotion for a possible fungal cause. Again, treatment provided no improvement.

He was then evaluated by dermatology. On physical examination, the patient had edema, warmth, and induration of the left lower leg. There also was an annular and serpiginous indurated plaque with minimal scale on the left lower leg (Figure 1). A firm, dark red to purple plaque on the left medial thigh with mild scale was present. There also was scaling of the right plantar foot.

Skin biopsy revealed a dermal capillary proliferation with a scattering of inflammatory cells including eosinophils as well as dermal fibrosis (Figure 2). Periodic acid–Schiff and human herpesvirus 8 (HHV-8) immunostains were negative. Considering the degree and depth of vascular proliferation, Mali-type acroangiodermatitis (AAD) was the favored diagnosis.

Patient 2
A 72-year-old white man presented with a firm asymptomatic growth on the left dorsal forearm of 3 months’ duration. It was located near the site of a prior squamous cell carcinoma that was excised 1 year prior to presentation. The patient had no treatment or biopsy of the presenting lesion. His medical and surgical history included polycystic kidney disease and renal transplantation 4 years prior to presentation. He also had an arteriovenous fistula of the left arm. His other chronic diseases included chronic obstructive lung disease, congestive heart failure, hypertension, type 2 diabetes mellitus, and obstructive sleep apnea.

On physical examination, the patient had a 1-cm violaceous nodule on the extensor surface of the left mid forearm. An arteriovenous fistula was present proximal to the lesion on the left arm (Figure 3).

Skin biopsy revealed a tightly packed proliferation of small vascular channels that tested negative for HHV-8, tumor protein p63, and cytokeratin 5/6. Erythrocytes were noted in the lumen of some of these vessels. Neutrophils were scattered and clustered throughout the specimen (Figure 4A). Blood vessels were highlighted with CD34 (Figure 4B). Grocott-Gomori methenamine-silver stain was negative for infectious agents. These findings favored AAD secondary to an arteriovenous malformation, consistent with Stewart-Bluefarb syndrome (SBS).

 

Comment

Presentation of AAD
Acroangiodermatitis is a rare chronic inflammatory skin process involving a reactive proliferation of capillaries and fibrosis of the skin that resembles Kaposi sarcoma both clinically and histopathologically. The condition has been reported in patients with chronic venous insufficiency,¹ congenital arteriovenous malformation,² acquired iatrogenic arteriovenous fistula,³ paralyzed extremity,⁴ suction socket lower limb prosthesis (amputees),⁵ and minor trauma.^6-8 The lesions of AAD tend to be circumscribed, slowly evolving, red-violaceous (or brown or dusky) macules, papules, or plaques that may become verrucous or develop into painful ulcerations. They generally occur on the distal dorsal aspects of the lower legs and feet.¹¹⁰

Variants of AAD
Mali et al⁹ first reported cutaneous manifestations resembling Kaposi sarcoma in 18 patients with chronic venous insufficiency in 1965. Two years later, Bluefarb and Adams¹⁰ described kaposiform skin lesions in one patient with a congenital arteriovenous malformation without chronic venous insufficiency. It was not until 1974, however, that Earhart et al¹¹ proposed the term pseudo-Kaposi sarcoma.^10,11 Based on these findings, AAD is described as 2 variants: Mali type and SBS.

Mali-type AAD is more common and typically occurs in elderly men. It classically presents bilaterally on the lower extremities in association with severe chronic venous insufficiency.⁵ Skin lesions usually occur on the medial aspect of the lower legs (as in patient 1), dorsum of the heel, hallux, or second toe.¹²

The etiology of Mali-type AAD is poorly understood. The leading theory is that the condition involves reduced perfusion due to chronic edema, resulting in neovascularization, fibroblast proliferation, hypertrophy, and inflammatory skin changes. When AAD occurs in the setting of a suction socket prosthesis, the negative pressure of the stump-socket environment is thought to alter local circulation, leading to proliferation of small blood vessels.^5,13

Stewart-Bluefarb syndrome usually involves a single extremity in young adults with congenital arteriovenous malformations, amputees, and individuals with hemiplegia or iatrogenic arteriovenous fistulae (as in patient 2).¹ It was once thought to occur secondary to Klippel-Trenaunay-Weber syndrome; however, SBS rarely is accompanied by limb hypertrophy.⁹ Pathogenesis is thought to involve an angiogenic response to a high perfusion rate and high oxygen saturation, which leads to fibroblast proliferation and reactive endothelial hyperplasia.^1,14

Diagnosis and Differential Diagnosis
Prompt identification of an underlying arteriovenous anomaly is critical, given the sequelae of high-flow shunts, which may result in skin ulceration, limb length discrepancy, cortical thinning of bone with regional osteoporosis, and congestive heart failure.^1,5 Duplex ultrasonography is the first-line diagnostic modality because it is noninvasive and widely available. The key doppler feature of an arteriovenous malformation is low resistance and high diastolic pulsatile flow,¹ which should be confirmed with magnetic resonance angiography or computed tomography angiography if present on ultrasonography.

The differential diagnosis of AAD includes Kaposi sarcoma, reactive angioendotheliomatosis, diffuse dermal angiomatosis, intravascular histiocytosis, glomeruloid angioendotheliomatosis, and angiopericytomatosis.^15,16 These entities present as multiple erythematous, violaceous, purpuric patches and plaques generally on the extremities but can have a widely varied distribution. Some lesions evolve to necrosis or ulceration. Histopathologic analysis is useful to differentiate these entities.

Histopathology
The histopathologic features of AAD can be nonspecific; clinicopathologic correlation often is necessary to establish the diagnosis. Features include a proliferation of small thick-walled vessels, often in a lobular arrangement, in an edematous papillary dermis. Small thrombi may be observed. There may be increased fibroblasts; plump endothelial cells; a superficial mixed infiltrate comprised of lymphocytes, histiocytes, and eosinophils; and deposition of hemosiderin.^2,5 These characteristics overlap with features of Kaposi sarcoma; AAD, however, lacks slitlike vascular spaces, perivascular CD34⁺ expression, and nuclear atypia. A negative HHV-8 stain will assist in ruling out Kaposi sarcoma.^1,17

Management
Treatment reports are anecdotal. The goal is to correct underlying venous hypertension. Conservative measures with compression garments, intermittent pneumatic compression, and limb elevation are first line.¹⁸ Oral antibiotics and local wound care with topical emollients and corticosteroids have been shown to be effective treatments.^19-21

Oral erythromycin 500 mg 4 times daily for 3 weeks and clobetasol propionate cream 0.05% healed a lower extremity ulcer in a patient with Mali-type AAD.²¹ In another patient, conservative treatment of Mali-type AAD failed, but rapid improvement of 2 lower extremity ulcers resulted after 3 weeks of oral dapsone 50 mg twice daily.²²

A tissue matrix–protective agent (a heparan sulfate mimetic) was reported to completely resolve a patient’s lower extremity ulcer secondary to SBS after other treatment modalities failed.¹⁹ In the SBS variant of AAD, treatment should be directed toward obliterating the underlying arteriovenous malformation, which can be achieved by selective embolization, endovenous ablation, sclerotherapy, or surgical intervention.^1,2

Conclusion

Acroangiodermatitis is a rare entity that is characterized by erythematous violaceous papules and plaques of the extremities, commonly in the setting of chronic venous insufficiency or an arteriovenous shunt. Histopathologic analysis shows proliferation of capillaries with fibrosis, extravasation of erythrocytes, and deposition of hemosiderin without the spindle cells and slitlike vascular spaces characteristic of Kaposi sarcoma. Detection of an underlying arteriovenous malformation is essential, as the disease can have local and systemic consequences, such as skin ulceration and congestive heart failure.¹ Treatment options are conservative, directed toward local wound care, compression, and management of complications, such as ulceration and infection, as well as obliterating any underlying arteriovenous malformation.