Linear IgA bullous dermatosis: comparison between the drug-induced and spontaneous forms.

BACKGROUND: Linear IgA bullous dermatosis (LABD) is a rare autoimmune blistering skin disorder characterized by linear deposits of IgA along the dermoepidermal junction, visualized by direct immunofluorescence (DIF). It is usually spontaneous and drug induced.

OBJECTIVES: To compare the clinical and histological forms of LABD.

METHODS: This retrospective single-centre cohort study concerned 28 patients diagnosed with LABD between 1 January 1995 and 31 December 2010. Imputability, determined according to the French imputability method (modified Bégaud score) and Naranjo score, enabled classification into drug-induced and spontaneous LABD groups. Clinical and histological features were compared by blinded analysis of images and histological patterns.

RESULTS: Sixteen patients had spontaneous LABD and 12 had drug-induced LABD. Nikolsky sign and large erosions were significantly more frequent in drug-induced than spontaneous LABD (P = 0.003 and P = 0.03, respectively), with no between-group differences for erythematous plaques, target or target-like lesions, string of pearls, location, mucosal involvement or histological features.

CONCLUSIONS: Drug-induced LABD was more severe than the spontaneous form, with lesions mimicking toxic epidermal necrolysis. Because LABD may be polymorphic and sometimes life threatening, DIF assay is recommended for all patients with Nikolsky sign and large erosions.