Drug-induced linear IgA bullous dermatosis: report of six cases and review of the literature.

Background: Linear IgA bullous dermatosis (LABD) is an autoimmune subepidermal blistering disease that may be associated with drug exposure. Objective: Our purpose was to compare the clinical, pathologic, and immunofluorescence findings in drug-induced LABD with those in the idiopathic type. Methods: Six patients with an acute drug eruption were identified who had linear IgA deposition at the basement membrane zone (BMZ). Lesional tissue was examined by brightfield microscopy, and perilesional tissue was examined by direct immunofluorescence (DIF). The presence of circulating BMZ antibody was assayed by indirect immunofluorescence (IIF) on monkey esophagus (ME) and salt-split human skin (SS). Results: Histopathologic examination showed subepidermal bullae with varying numbers of inflammatory cells. DIF showed linear IgA at the BMZ; three of the patients also had weak deposition of C3 at the BMZ. Serum from five patients was studied by IIF. One patient had circulating IgA BMZ antibodies in a titer of 1:80 on ME, localized to the dermal side on SS. All patients were free of lesions within 5 weeks after discontinuation of the drug. Conclusion: Drug-induced LABD is a self-limited eruption characterized by linear deposition of IgA without IgG at the BMZ. Most patients lack circulating antibodies. The distribution of lesions and the course of the disease differ from those of idiopathic LABD.