Erythema Multiforme

A 55-year-old woman had a 10-day history of a nonproductive cough and a painful rash on both palms for 5 days. The eruption subsequently spread over her entire body. Erythema multiforme—a reactive dermatosis exacerbated by a variety of stimuli—was diagnosed. The hive-like rash is more tender than pruritic and features bull’s-eye lesions. The 2 classic infectious causes are herpes simplex virus and Mycoplasma pneumoniae. Further evaluation of the patient confirmed the mycoplasmal source; the infection responded to appropriate antibiotic therapy. The skin eruption improved dramatically after a few days of systemic corticosteroid therapy. (Case and photograph courtesy of Dr David L. Kaplan.)