Clear Cell Acanthoma: Clinicopathologic Analysis of 37 New Cases

Abstract

The clinical and histologic features of 37 new cases of clear cell acanthoma were analyzed. All lesions were solitary; most were asymptomatic, erythematous nodules less than 1 cm. in diameter. The median age of the patients was 64 years, the median duration of the lesions was 3 years, and the incidences in both sexes were equal. Thirty-five of the tumors occurred on the lower limbs. Many were clinically interpreted as basal cell carcinoma, histiocytoma, or granuloma pyogenicum. Histologic examination disclosed acanthotic rete ridges with large, pale, glycogen-rich malpighian cells covered by serous crust and parakeratotic scale. At each margin there was a sharp transition to dark cell acanthosis in two or three rete ridges which were covered by thick horn and a hyperplastic granular layer. Lateral to this was a second transition to normal epidermis. Rich vascularity and a perivascular lymphocytic infiltrate were present in the cutis.