Erythema multiforme (EM) is an acute, immune-mediated condition characterized by the appearance of distinctive target-like lesions on the skin. These lesions are often accompanied by erosions or bullae involving the oral, genital, and/or ocular mucosae (picture 1A-F). Erythema multiforme major is the term used to describe EM with mucosal involvement; erythema multiforme minor refers to EM without mucosal disease. (See "Pathogenesis, clinical features, and diagnosis of erythema multiforme", section on 'Clinical manifestations'.)
A variety of factors have been implicated in the pathogenesis of EM. The disorder is most commonly induced by infection, with herpes simplex virus (HSV) being the most frequent precipitator. The clinical course of EM is usually self-limited, resolving within weeks without significant sequelae. However, in a minority of cases, the disease recurs frequently over the course of years.
Similarities in clinical and histopathologic findings have led to controversy over the distinction between EM and Stevens-Johnson syndrome (SJS), an often drug-induced disorder that may present with cutaneous targetoid lesions and mucosal erosions. However, there is suggestive evidence that EM with mucous membrane involvement and SJS are different diseases with distinct causes . The term erythema multiforme major should not be used to refer to SJS. (See "Stevens-Johnson syndrome and toxic epidermal necrolysis: Pathogenesis, clinical manifestations, and diagnosis".)
The treatment and prognosis of acute and recurrent EM will be reviewed here. The epidemiology, pathogenesis, clinical features, evaluation, and diagnosis of this disorder are discussed separately. (See "Pathogenesis, clinical features, and diagnosis of erythema multiforme".)
TREATMENT OF ACUTE EM
The treatment of acute erythema multiforme (EM) varies according to disease severity. The clinical course of an episode of EM is self-limited, although the disease may recur. (See 'Prevention of recurrent EM' below.)