Pityriasis rotunda.

Pityriasis rotunda is an uncommon cutaneous disorder consisting of asymptomatic, strikingly circular, scaly lesions on the trunk and extremities, with the histologic appearance of ichthyosis vulgaris. Previous cases have been described in Japanese, South African, and West Indian persons, usually in association with an underlying serious systemic disease. A case of pityriasis rotunda in a 32-year-old black man in whom no diagnosable disorder could be demonstrated is presented.