Erythema multiforme

Published on 11/06/2015 by admin

Filed under Pediatrics

Last modified 22/04/2025

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Early target lesions with a central dusky and an outer edematous zone.

Fully developed target lesions with central necrotic crusted zone, edematous zone and outer red zone.

EM. Oral shallow ulcers with a red base on buccal mucosa.

Isomorphic phenomenon (Koebner) at site of antecedent scratch on arm of teen with EM.

The abrupt onset of symmetrical red papules that evolve into diagnostic target lesions characterizes EM.

Target lesions are oval to round, fixed lesions that have three distinct zones − a central zone of epidermal damage seen as blister or crust formation, an edematous middle zone and a red outer zone. Target lesions must display epidermal damage. Giant urticaria with a clear center is often mislabeled as target lesions.

EM skin lesions are fixed; that is, once they appear they stay at the same site for 7 to 21 days, whereas urticaria lesions move to different skin sites within hours. Target lesions may itch or be painful. Herpes labialis may precede the onset of EM, but most often a prodrome is absent. The dorsum of the hands, palms and soles, and extensor extremities are the sites most often involved.

Sites of skin trauma that preceded the onset of lesions may develop target lesions in the configuration of the injury (Koebner phenomenon).

Oral mucosa is involved and in half of children a few shallow oral lesions will be seen. EM is uncommon, recurrent and predominantly seen in older children and teens. Recurrences are usually 1 or 2 each year.

The majority of children with EM will have HSV-1 or -2 associated disease and have detectable virus within their skin lesions even without a definite history of a preceding HSV infection. They may have delayed clearing of HSV from their skin. In a few, EBV or CMV infections may be precipitating agents.

Symptomatic treatment with wet compresses and oral antihistamines will help with itching or pain.

Antiviral treatment even at the onset of symptoms is ineffective, as the skin injury has already been initiated.

Good sun protection can be useful in preventing the antecedent recurrent HSV.

Systemic steroids should be avoided as their use may result in more frequent recurrences and prolonged, almost continuous episodes.