A Case of Pigmented Clear Cell Acanthoma / 대한피부과학회지

ABSTRACT

Clear cell acanthoma is a rare, benign, epidermal tumor. These tumors usually present as solitary lesions, often localized on the lower legs of middle aged or elderly individuals. Pigmented clear cell acanthoma, a variant of clear cell acanthoma, presents as macroscopically visible brown to black-colored, flat or dome-shaped, sharply-dermacated papules or nodules. Histopathologic findings in these tumors reveal markedly epidermal hyperplasia, with exception of the cells in the basal layer. Also, most of the epithelium showed pallor and slight enlargement. With these pigmented type tumors, dermal melanophages are often noticeable on low-power magnification, plus increased melanocytes with melanin granules in the epidermis. A 41-year-old man presented with a 7-year history of a 1.2x0.8cm sized, black plaque on the right inner thigh. The histologic findings revealed the typical features of pigmented clear cell acanthoma.