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Clinical Features

Erythema multiforme (EM) strikes all ages, with the highest incidence in young adults (20 to 40 years of age). It affects males twice as often as females, and occurs more commonly in the spring and fall. EM is an acute inflammatory skin disease with presentations that range from a mild papular eruption (EM minor) to diffuse vesiculobullous lesions with mucous membrane involvement and systemic toxicity (Stevens–Johnson syndrome). Precipitating factors include infection (mycoplasma and herpes simplex), drugs (antibiotics and anticonvulsants), and malignancy. No specific cause is found in about half of the cases.

Malaise, arthralgias, myalgias, fever, a generalized burning sensation, and diffuse pruritus may precede the development of skin lesions. Skin lesions begin as erythematous papules and macular lesions followed by the development of target lesions in 24 to 48 hours. Lesions can be diffused and may be located on the palms and soles. Urticarial plaques, vesicles, bullae, vesiculobullous lesions, and mucosal (oral, conjunctival, respiratory, and genitourinary) erosions may also develop (Fig. 154–1). Systemic toxicity along with significant fluid and electrolyte deficiencies and secondary infections may be seen in severe disease.

Diagnosis and Differential

Target lesions are highly suggestive of EM. The presence of mucosal involvement suggests Stevens–Johnson syndrome. The differential diagnosis includes herpetic infections, vasculitis, toxic epidermal necrolysis, primary blistering disorders, Kawasaki disease, and the toxic and infectious erythemas.

Emergency Department Care and Disposition

  1. Patients without systemic manifestation or mucous membrane involvement may be managed as outpatients with dermatologic consultation. Prednisone 60 to 80 mg PO daily for 3 to 5 days are often prescribed for mild disease but are unproven to change duration and outcomes. Acyclovir may reduce recurrent HSV-related EM.

  2. Admit patients with extensive disease or systemic toxicity for critical care and consultation with a dermatologist and ophthalmologist. Intensively manage fluid, electrolyte, infectious, nutritional, and thermoregulatory issues. Diphenhydramine and lidocaine rinses provide symptomatic relief for stomatitis. Cool Burrow’s solution (5% aluminum acetate) compresses can be applied to blistered regions.


Toxic epidermal necrolysis (TEN) is a severe inflammatory skin disease that strikes all ages and both sexes equally. Some authorities consider TEN to be a variant of Stevens–Johnson syndrome.

Clinical Features

Potential etiologies include chemicals, infections, and malignancy, but medications are the most common causes of TEN. Malaise, anorexia, myalgias, arthralgias, fever, and upper respiratory infection symptoms may precede skin findings by 1 to 2 weeks. Skin findings progress from tender erythematous areas that become confluent within hours to flaccid bullae and erosions with exfoliation (Fig. 154–2). A positive Nikolsky sign is slippage of the epidermis from the dermis ...

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