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July 1989

Ulcerated Tumor on the Scalp

Arch Dermatol. 1989;125(7):987-988. doi:10.1001/archderm.1989.01670190121018

REPORT OF A CASE  A 26-year-old man presented with an 8-month history of an enlarging, painful tumor on the scalp. The tumor occasionally discharged watery fluid. There was no history of trauma to the area. The patient had borderline hypertension, which was controlled by diet. He was receiving no medication.Physical examination revealed a 4-cm, soft, tender, erythematous, superficially ulcerated tumor at the vertex of the scalp. Serous fluid could be expressed from the lesion. No lymphadenopathy was present. The tumor is shown prior to and following preparation for surgery (Figs 1 and 2).Representative sections of an excisional biopsy specimen are shown (Figs 3 and 4).What is your diagnosis?

DIAGNOSIS:  Clear-cell hidradenoma.

HISTOPATHOLOGIC FINDINGS  Beneath a slightly acanthotic epidermis, and in several areas associated with the surface epithelium, was a well-circumscribed nodule. The nodule extended into the subcutaneous fat. It was composed of two populations of cells. Each cell population had uniform round to oval vesicular nuclei.