Disciform erythrasma.

A case of disciform erythrasma is presented. This unusual manifestation of a common cutaneous infection may mimic other dermatologic disorders, including lichen sclerosus et atrophicus and plaque-type parapsoriasis. The condition is characterized by an atrophic appearing surface, located in nonintertriginous areas. Appropriate diagnostic procedures easily differentiate disciform erythrasma. These include Wood's light examination, potassium hydroxide preparation, and skin scrapings or tissue sections stained with Gram stain, periodic acid-Schiff, Giemsa, or methylene blue.