ERYTHEMA MULTIFORME

Erythema multiforme is a skin condition of unknown etiology, but some authors suggest that the disease is mediated by deposition of immune complex ( mostly IgM ) in the superficial microvasculature of the skin and oral mucous membrane that usually follows an antecedent infection or drug exposure. It varies from a mild, self-limited rash (E. multiforme minor) to a severe, life-threatening form (E. multiforme major, or Stevens-Johnson syndrome) that also involves mucous membranes.
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Erythema multiforme is a skin disease that causes lesions and redness around the lesions. [more]Erythema multiforme - Community and Resources

Noun
1. a red rash caused by hypersensitivity to a drug or disease or other allergen
(hypernym) erythema