Linear IgA bullous dermatosis mimicking erythema multiforme in adult.

This report describes a 49-year-old woman with an erythema multiforme--like rash and direct immunofluorescence showing linear IgA deposits at the dermoepidermal junction. Light microscopy revealed features of bullous pemphigoid, dermatitis herpetiformis, and erythema multiforme; immunoelectron microscopy demonstrated IgA deposition beneath the lamina densa about anchoring fibrils. These data provide additional information about the variable clinical and histologic manifestations of the adult linear IgA bullous dermatosis and emphasize the diagnostic dilemmas of light microscopy, which are resolved by immunohistochemical methods.