Erythema Multiforme

Erythema multiforme (EM) is an acute, self-limited, and sometimes recurring skin condition that is considered to be a type IV hypersensitivity reaction associated with certain infections, medications, and other various triggers.

The clinical descriptions are as follows:

• Erythema multiforme minor - Typical targets or raised, edematous papules distributed acrally
• Erythema multiforme major - Typical targets or raised, edematous papules distributed acrally with involvement of one or more mucous membranes; epidermal detachment involves less than 10% of TBSA.
• SJS/TEN - Widespread blisters predominant on the trunk and face, presenting with erythematous or pruritic macules and one or more mucous membrane erosions; epidermal detachment is less than 10% TBSA for Steven-Johnson syndrome / toxic epidermal necrolysis and 30% or more for toxic epidermal necrolysis.

Symptoms

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 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.

Treatment & Management

For all forms of erythema multiforme (EM), the most important treatment is usually symptomatic, including oral antihistamines, analgesics, local skin care, and soothing mouthwashes (eg, oral rinsing with warm saline or a solution of diphenhydramine, xylocaine, and).

Topical steroids (Clobetasol, Dexamethasone, hydrocortisone) may be considered. In severe cases, prehospital personnel may need to treat respiratory complications and fluid imbalances aggressively, in the same manner as thermal burns.

Avoid systemic corticosteroids in minor cases. In severe cases, their use is controversial, because these agents do not improve prognosis and may increase risk of complications.

Hospitalization Erythema multiforme (EM) major may require hospitalization for the treatment of complications and sequelae (e.g., severe mucous membrane involvement is present or with impaired oral intake, dehydration, or secondary infection) and to manage the patient's fluid and electrolytes. The most severe cases should be managed in intensive care or burn units.