User login
For years, this 33-year-old woman has had a firm, pea-sized nodule on her left upper back. It was never a problem until recently, when it suddenly enlarged and became red, swollen, and tender.
She was prescribed antibiotics (trimethoprim and sulfa) by a provider at her local urgent care center. Dubious of the diagnosis—carbuncle—she sought referral to dermatology.
The patient claims to be in otherwise excellent health, with no history of similar problems. She denies manual manipulation of the lesion.
EXAMINATION
The patient is afebrile and in no distress. On her upper left back is a round, cystic lesion measuring 3.5 cm. It appears swollen and red. The erythema, though impressive, is confined to
the area immediately around the margins. Palpation reveals increased warmth and modest tenderness. A central punctum can be seen in the center of the fluctuant lesion.
After a brief discussion of options, the lesion is incised and drained under sterile conditions with lidocaine and epinephrine. Cheesy, odoriferous material is expressed, effectively flattening the lesion.
What is the diagnosis?
Epidermal cysts are utterly common, especially in oil-rich areas such as the upper back. They are often mistakenly called sebaceous cysts; however, true sebaceous cysts are quite rare and contain only pure, clear oil.
When ruptured by trauma, epidermal cysts become inflamed and cheesy material leaks into deep tissues. This activates an immune response in which the body sends out white cells to clean up the leakage—what we call inflammation.
There are many types of cysts (eg, acne cysts, ganglion cysts, Bartholin gland cysts) but none resemble epidermal cysts. Providers often mistake epidermal cysts for carbuncles or boils and may prescribe oral or systemic antibiotics, or incise the cysts and pack the space. The truth is that inflamed epidermal cysts do not represent infection—hence the limited area of redness. By contrast, cellulitis or carbuncle would manifest with tenderness and blush of erythema over the entire area.
The fact that this lesion arose from a longstanding antecedent nodule is consistent with the diagnosis, as are the cheesy, odoriferous contents liberated by incision and drainage. Liberating the contents merely buys the patient relief from the pressure and pain, since the cyst wall is still present and will almost certainly fill up again. The ultimate solution is excision after the emptied cyst has had time to shrink back to its original size, which will minimize the scarring. There is no need to pack such cysts after incision and drainage, though they will continue to drain for a few days.
TAKE-HOME LEARNING POINTS
- Epidermal cysts are common, especially in oil-rich areas such as the face, back, chest, and neck.
- Epidermal cysts are often mistakenly called sebaceous cysts, but these are actually quite rare, containing clear sebum (oil) and no cheesy material.
- Even though such inflamed cysts are often mistaken for boils, carbuncles, and abscesses, they have nothing to do with bacteria or infection and therefore do not require antibiotics or packing after incision and drainage.
- For recurrent inflamed cysts, the treatment of choice is complete excision, done only after the cyst has shrunk to its smallest size.
For years, this 33-year-old woman has had a firm, pea-sized nodule on her left upper back. It was never a problem until recently, when it suddenly enlarged and became red, swollen, and tender.
She was prescribed antibiotics (trimethoprim and sulfa) by a provider at her local urgent care center. Dubious of the diagnosis—carbuncle—she sought referral to dermatology.
The patient claims to be in otherwise excellent health, with no history of similar problems. She denies manual manipulation of the lesion.
EXAMINATION
The patient is afebrile and in no distress. On her upper left back is a round, cystic lesion measuring 3.5 cm. It appears swollen and red. The erythema, though impressive, is confined to
the area immediately around the margins. Palpation reveals increased warmth and modest tenderness. A central punctum can be seen in the center of the fluctuant lesion.
After a brief discussion of options, the lesion is incised and drained under sterile conditions with lidocaine and epinephrine. Cheesy, odoriferous material is expressed, effectively flattening the lesion.
What is the diagnosis?
Epidermal cysts are utterly common, especially in oil-rich areas such as the upper back. They are often mistakenly called sebaceous cysts; however, true sebaceous cysts are quite rare and contain only pure, clear oil.
When ruptured by trauma, epidermal cysts become inflamed and cheesy material leaks into deep tissues. This activates an immune response in which the body sends out white cells to clean up the leakage—what we call inflammation.
There are many types of cysts (eg, acne cysts, ganglion cysts, Bartholin gland cysts) but none resemble epidermal cysts. Providers often mistake epidermal cysts for carbuncles or boils and may prescribe oral or systemic antibiotics, or incise the cysts and pack the space. The truth is that inflamed epidermal cysts do not represent infection—hence the limited area of redness. By contrast, cellulitis or carbuncle would manifest with tenderness and blush of erythema over the entire area.
The fact that this lesion arose from a longstanding antecedent nodule is consistent with the diagnosis, as are the cheesy, odoriferous contents liberated by incision and drainage. Liberating the contents merely buys the patient relief from the pressure and pain, since the cyst wall is still present and will almost certainly fill up again. The ultimate solution is excision after the emptied cyst has had time to shrink back to its original size, which will minimize the scarring. There is no need to pack such cysts after incision and drainage, though they will continue to drain for a few days.
TAKE-HOME LEARNING POINTS
- Epidermal cysts are common, especially in oil-rich areas such as the face, back, chest, and neck.
- Epidermal cysts are often mistakenly called sebaceous cysts, but these are actually quite rare, containing clear sebum (oil) and no cheesy material.
- Even though such inflamed cysts are often mistaken for boils, carbuncles, and abscesses, they have nothing to do with bacteria or infection and therefore do not require antibiotics or packing after incision and drainage.
- For recurrent inflamed cysts, the treatment of choice is complete excision, done only after the cyst has shrunk to its smallest size.
For years, this 33-year-old woman has had a firm, pea-sized nodule on her left upper back. It was never a problem until recently, when it suddenly enlarged and became red, swollen, and tender.
She was prescribed antibiotics (trimethoprim and sulfa) by a provider at her local urgent care center. Dubious of the diagnosis—carbuncle—she sought referral to dermatology.
The patient claims to be in otherwise excellent health, with no history of similar problems. She denies manual manipulation of the lesion.
EXAMINATION
The patient is afebrile and in no distress. On her upper left back is a round, cystic lesion measuring 3.5 cm. It appears swollen and red. The erythema, though impressive, is confined to
the area immediately around the margins. Palpation reveals increased warmth and modest tenderness. A central punctum can be seen in the center of the fluctuant lesion.
After a brief discussion of options, the lesion is incised and drained under sterile conditions with lidocaine and epinephrine. Cheesy, odoriferous material is expressed, effectively flattening the lesion.
What is the diagnosis?
Epidermal cysts are utterly common, especially in oil-rich areas such as the upper back. They are often mistakenly called sebaceous cysts; however, true sebaceous cysts are quite rare and contain only pure, clear oil.
When ruptured by trauma, epidermal cysts become inflamed and cheesy material leaks into deep tissues. This activates an immune response in which the body sends out white cells to clean up the leakage—what we call inflammation.
There are many types of cysts (eg, acne cysts, ganglion cysts, Bartholin gland cysts) but none resemble epidermal cysts. Providers often mistake epidermal cysts for carbuncles or boils and may prescribe oral or systemic antibiotics, or incise the cysts and pack the space. The truth is that inflamed epidermal cysts do not represent infection—hence the limited area of redness. By contrast, cellulitis or carbuncle would manifest with tenderness and blush of erythema over the entire area.
The fact that this lesion arose from a longstanding antecedent nodule is consistent with the diagnosis, as are the cheesy, odoriferous contents liberated by incision and drainage. Liberating the contents merely buys the patient relief from the pressure and pain, since the cyst wall is still present and will almost certainly fill up again. The ultimate solution is excision after the emptied cyst has had time to shrink back to its original size, which will minimize the scarring. There is no need to pack such cysts after incision and drainage, though they will continue to drain for a few days.
TAKE-HOME LEARNING POINTS
- Epidermal cysts are common, especially in oil-rich areas such as the face, back, chest, and neck.
- Epidermal cysts are often mistakenly called sebaceous cysts, but these are actually quite rare, containing clear sebum (oil) and no cheesy material.
- Even though such inflamed cysts are often mistaken for boils, carbuncles, and abscesses, they have nothing to do with bacteria or infection and therefore do not require antibiotics or packing after incision and drainage.
- For recurrent inflamed cysts, the treatment of choice is complete excision, done only after the cyst has shrunk to its smallest size.