[Erythema multiforme : target deciphering].

Erythema multiforme is an immune-mediated skin reaction characterized by target-shaped lesions. These lesions are described here and compared with their clinical mimickers. The condition is mainly secondary to an infection, typically Herpes simplex virus infection, and more rarely to medication, autoimmune disease, hematological neoplasia or radiation. Diagnosis is clinical. Due to its diverse manifestations, a skin biopsy and immunohistochemical analyses can confirm the condition and rule out differential diagnoses. Treatment is symptomatic and combined with management of the underlying cause.