The patient is a 57-year-old man requesting removal of a growth on his left upper thigh. The lesion has been increasing in size for at least 1 year and is frequently traumatized by clothing. Examination revealed a 1.2cm hyperpigmented projection that felt soft on palpation. No similar lesions were noted elsewhere.
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Shave biopsy revealed a poroma, a benign adnexal neoplasm that arises from a sweat gland duct. Poromas were first described in 1956 and were believed to be exclusively of eccrine gland origin.1 A case of apocrine poroma was first described in 19882 and are occasionally documented.3
Poromas present as solitary dome-shaped papules or nodules that range in coloration from flesh-toned to reddish blue. The most common location is on the hands and feet4, and lesions infrequently occur on the face and neck.5 Full excision is recommended as transformation into malignant porocarcinoma may occur in up to 18% of lesions.6
Stephen Schleicher, MD, is an associate professor of medicine at the Commonwealth Medical College in Scranton, Pennsylvania, and an adjunct assistant professor of dermatology at the Perelman School of Medicine at the University of Pennsylvania in Philadelphia.
- 1. Goldman P, Pinkus H, Rogin JR. Eccrine poroma: tumors exhibiting features of the epidermal sweat duct unit. AMA Arch Dermatol. 1956;74:511-521.
- 2. Requena L, Kiryu H, Bernard A, Ackerman MD, Carter D. Neoplasms with Apocrine Differentiation (Ackerman’s Histologic Diagnosis of Neoplastic Skin Diseases). New York: Lippincott Williams & Wilkins, 1998.
- 3. Kamiya H, Oyama Z, Kitajima Y. “Apocrine” poroma: review of the literature and case report. J Cutan Pathol. 2001;28:101-104.
- 4. Johnson RC, Rosenmeier GJ, Keeling JH. A painful step. Eccrine poroma. Arch Dermatol. 1992;128:1530, 1533.
- 5. Moore TO, Orman HL, Orman SK, Helm KF. Poromas of the head and neck. J Am Acad Dermatol. 2001;44:48-52.
- 6. Robson A, Greene J, Ansari N, et al. Eccrine porocarcinoma (malignant eccrine poroma): a clinicopathologic study of 69 cases. Am J Surg Pathol.2001;25:710-720.