Clear (Pale ) Cell Acanthoma

A 36-year-old gentleman presented to the Dermatology and Venereology outpatient clinic with a painless nodule of the volar aspect of the left forearm for six months (Panel A). On examination, there was a single, non-tender, smooth surface, and dome-shaped nodule. It was shiny with a reddish rim at its periphery. The nodule was excised completely as a treatment and for histopathological examination that shows it as a clear cell acanthoma (CCA) [panel B (H/E-4X) and C (H/E-10X)]. CCA is a rare benign cutaneous tumor of unknown cause. It is mostly presented as a painless, solitary, slowly growing, and pink-brown or red nodule that is seen mostly on the distal lower extremities of middle-aged and elderly patients. Multiple lesions and different morphologies such as polypoid, giant, atypical, pigmented, and cystic lesions can be seen. Other sites like the abdomen, areola, face, and scrotum can be affected. CCA has specific dermoscopic features in which the blood vessels are arranged in a string-like appearance, but the diagnosis is rarely done without biopsy. Histopathological examination reveals epidermal acanthosis with a psoriasiform pattern of pale keratinocytes and spongiosis in association with dilated blood vessels of the edematous dermal papillae. CCA is treated by surgery such as excision, CO2 laser, or cryosurgery. With a weekly regular follow-up of the patient for two months, the lesion was completely cured.