Erythema Multiforme

Etiology • Many cases preceded by infection with herpes simplex; less
often with Mycoplasma pneumoniae or other organisms • May be related to drug consumption, including sulfonamides,
other antibiotics, analgesics, phenolphthalein-containing laxatives, barbiturates
• Another trigger may be radiation therapy. • Essentially an immunologically mediated reactive process,
possibly related to circulating immune complexes
Clinical Presentation • Acute onset of multiple, painful, shallow ulcers and erosions

with irregular margins • Early mucosal lesions are macular, erythematous, and occa-
sionally bullous. • May affect oral mucosa and skin synchronously or
metachronously • Lips most commonly affected with eroded, crusted, and
hemorrhagic lesions (serosanguinous exudate) known as Stevens-Johnson syndrome when severe
• Predilection for young adults • As many as one-half of oral cases have associated erythematous
to bullous skin lesions. • Target or iris skin lesions may be noted over extremities. • Genital and ocular lesions may occur. • Usually self-limiting; 2- to 4-week course • Recurrence is common.
Diagnosis • Appearance • Rapid onset • Multiple site involvement in one-half of cases • Biopsy results often helpful, but not always diagnostic
Differential Diagnosis • Viral infection, in particular, acute herpetic gingivostomatitis
(Note: Erythema multiforme rarely affects the gingiva.)
• Pemphigus vulgaris • Major aphthous ulcers • Erosive lichen planus • Mucous membrane (cicatricial) pemphigoid
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Treatment • Mild (minor) form: symptomatic/supportive treatment with
adequate hydration, liquid diet, analgesics, topical corticosteroid agents
• Severe (major) form: systemic corticosteroids, parenteral fluid replacement, antipyretics
• If evidence of an antecedent viral infection or trigger exists, systemic antiviral drugs during the disease or as a prophylactic measure may help.
• See “Therapeutics” section for details.
Prognosis • Generally excellent • Recurrences common