Erythema multiforme (EM) strikes all ages, with the highest incidence in young adults (20 to 40 years), 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 (EM major or Stevens-Johnson syndrome). Precipitating factors include infection (mycoplasma and herpes simplex), drugs (antibiotics and anticonvulsants), and malignancy. No cause is found in about 50% of cases.
Malaise, arthralgias, myalgias, fever, a generalized burning sensation, and diffuse pruritus may precede skin lesions. The initial skin lesions are erythematous papules and maculopapules followed by target lesions in 24 to 48 hours. Urticarial plaques, vesicles, bullae, vesiculobullous lesions, and mucosal (oral, conjunctival, respiratory, and genitourinary) erosions may also develop (Fig. 154-1). Significant systemic toxicity along with significant fluid and electrolyte deficiencies and secondary infection may be seen in severe disease.
Diagnosis and Differential
Target lesions are highly suggestive of EM. The presence of mucosal involvement suggests EM major/Stevens-Johnson syndrome. The differential diagnosis includes herpetic infections, vasculitis, toxic epidermal necrolysis, primary blistering disorders, Kawasaki disease, and toxic infectious erythemas.
Emergency Department Care and Disposition
Patients without systemic manifestation and mucous membrane involvement may be managed as outpatients with dermatologic consultation. Systemic steroid bursts (prednisone 60 to 80 milligrams PO daily) are prescribed for mild disease but are unproven to change duration and outcomes. Acyclovir may reduce recurrent HSV-related EM.
Patients with extensive disease or systemic toxicity require critical care admission and consultation with a dermatologist and ophthalmologist. Intensive management of fluid, electrolyte, infectious, nutritional, and thermoregulatory issues is required. Diphenhydramine and lidocaine rinses provide symptomatic relief for stomatitis. Cool Burrow solution (5% aluminum acetate) compresses are 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 EM major/Stevens-Johnson syndrome.
Potential etiologies include medications, chemicals, infections, and immunologic factors. Malaise, anorexia, myalgias, arthralgias, fever, and upper respiratory infection symptoms may precede skin findings by 1 to 2 weeks. Skin findings progress from erythroderma to flaccid bullae to erosions with exfoliation (Fig. 154-2). A Nikolsky sign is present (slippage of the epidermis from the dermis when slight tangential pressure of rubbing is applied). Mucosal lesions are present. Systemic toxicity is common. Acute and chronic complications are similar to those encountered in EM major patients. TEN is fatal in 25% to 35% of cases. Predictors of poor prognosis include advanced age, extensive disease, multiple medication use, leucopenia, ...