Adult linear IgA bullous dermatosis: a polymorphic disorder.

We report on two patients with unusual forms of adult linear IgA bullous dermatosis. One was a middle-aged woman who had targetoid lesions and bullae on her trunk and extremities. This patient first presented with lesions that clinically resembled erythema multiforme, but these evolved into a widespread eruption with bulging, elongated bullae. Examination of a biopsy specimen showed changes compatible with dermatitis herpetiformis and bullous pemphigoid. Findings on immunofluorescence studies showed deposition of linear IgA at the basement membrane zone. The second patient was an elderly woman with intensely pruritic vesicles whom we classified as having vesicular pemphigoid, until the linear IgA band on direct immunofluorescent test results became the predominant immunofluorescent finding. These cases are reported because of their unusual clinical presentations. The mechanism for the targetoid lesions in the first patient is discussed.