Pityriasis rotunda: two cases in black Americans.

Pityriasis rotunda is an uncommon cutaneous disorder consisting of asymptomatic, perfectly circular, scaling plaques on the trunk and extremities. Histopathologic findings are consistent with ichthyosis vulgaris. The majority of cases are seen in association with an underlying disease, and most authors believe that this entity represents a form of acquired ichthyosis. Previous cases have been restricted to certain geographic and ethnic groups (most commonly Japanese and South African Bantu). We report two cases of pithyriasis rotunda, both occurring in black Americans. We believe that these are the first reported cases seen in Americans.