Fast Five Quiz: How Much Do You Know About Erythema Multiforme?

William James, MD


February 15, 2018

The initial lesion is a dull-red, purpuric macule or urticarial plaque that expands slightly to a maximum of 2 cm over 24-48 hours. In the center, a small papule, vesicle, or bulla develops, flattens, and then may clear. An intermediate ring develops and becomes raised, pale, and edematous. The periphery gradually changes to become cyanotic or violaceous and forms a typical concentric "target" lesion. Some lesions consist of only 2 concentric rings. Polycyclic or arcuate lesions may occur. Some lesions appear at areas of previous trauma (Koebner phenomenon). Postinflammatory hyperpigmentation or hypopigmentation may occur. The Nikolsky sign is negative (ie, top layers of the skin do not slip away from the lower layers when slightly rubbed).

The lesions are symmetrical, predominantly on the acral extensor surfaces of the extremities, and they spread centripetally to involve the abdomen and back. Lesions may also coalesce and become generalized. The palms, neck, and face are frequently involved. Lesions of the soles and flexural aspects of the extremities are less common. A zosteriform distribution may be present.

Mucosal lesions usually heal without sequelae. The mucosal involvement in Stevens-Johnson syndrome is more severe and more extensive than that of erythema multiforme major. Generalized lymphadenopathy often accompanies erythema multiforme major.

Prodromal symptoms are usually absent or mild in persons with erythema multiforme minor, consisting of a mild, nonspecific upper respiratory tract infection. The abrupt onset of a rash usually occurs within 3 days, starting on the extremities symmetrically, with centripetal spreading. Pruritus is generally absent. In erythema multiforme major, 50% of patients have prodromes similar to an influenzalike prodrome, including moderate fever, general discomfort, cough, sore throat, vomiting, chest pain, and diarrhea (secondary to gastrointestinal tract ulceration). These symptoms have a classic time course of development and are usually present for 1-14 days before the cutaneous eruption occurs.

For more on the presentation of erythema multiforme, read here.


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