She Needs A-cyst-ance

DISCUSSION
The pathology report confirmed the lesions to be steatocystoma—in this case, part of an autosomal dominantly inherited condition called steatocystoma multiplex (SM). When these manifest as solitary lesions, they are known as steatocystoma simplex—a true sebaceous cyst, quite different from the common epidermal cyst that contains cheesy, odoriferous material and is frequently misnamed “sebaceous cyst.”

Steatocystoma can develop spontaneously, without any genetic predisposition. SM, however, is quite unusual (if not rare) and results from a defect in keratin 17 that allows the accumulation of sebum at the base of the follicle. It has no other pathologic implication.

However, in a case such as this, SM presents a real problem, because the only effective treatment is complete excision. This not only leaves a scar, but also, in those with skin of color, has the potential to produce hypertrophic scarring or even keloid formation. Worse, in many cases, the patient keeps developing cysts in new locations.

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TAKE-HOME LEARNING POINTS

• Steatocystoma multiplex (SM) is an autosomal dominant condition in which the patient, usually at puberty, develops sebum-filled cysts.
• These cysts can occur as solitary lesions (steatocystoma simplex) but more often manifest in multiples on the neck, face, chest, and arms.
• SM cysts are full of clear or yellowish sebum, unlike common epidermal cysts, which are filled with cheesy, often odoriferous material.
• The only effective treatment for SM cysts is complete excision.