Picture of Erythema Multiforme 1

Erythema multiforme (EM) is a cutaneous and mucosal hypersensitivity reaction with characteristic lesions in target triggered by certain antigenic stimuli. It represents an acute condition, sometimes recurrent, of the skin and mucosal membranes manifested by papular, bullous, and necrotic lesions. Its causes are variable and numerous. Most lesions appear in 48-72 hours and favor the extremities. The lesions remain localized to one site and heal within 7-21 days. Common precipitating factors include herpes simplex virus, histoplasmosis, and Epstein Barr virus.