Pityriasis Rotunda

Serwatka, Linda M.

Abstract

Pityriasis rotunda (PR) is an uncommon dermatosis characterized by perfectly round, scaly patches. Thus, it has been considered by some to be a dermatophyte infection. PR has also been associated with a variety of underlying systemic diseases. A case is reported, herein, of PR associated with Paget's disease of the bone. Potassium hydroxide (KOH) examination of scale from the lesions was negative. Histologically there was orthokeratotic hyperkeratosis, a normal granular layer, and a mild lymphohistiocytic perivascular infiltrate in the superficial dermis. Sections stained with methenamme silver were negative for fungus. These findings support the theory that PR is not a dermatophyte infection, but a variant of acquired ichthyosis. Treatment with an alpha hydroxy acid lotion is discussed.