Linear IgA bullous dermatosis in one of two piroxicam-induced eruptions: a distinct direct immunofluorescence trend revealed by the literature.

BACKGROUND The report focuses first on two patients with piroxicam-induced bullous eruption, one whose disease was diagnosed as linear IgA bullous dermatosis (LABD) and the other with no disease-specific immunologic findings using immunofluorescence methods. A review of the literature points to a distinctive direct immunofluorescence feature of drug-induced LABD cases. OBJECTIVE Our purposes were to focus on divergent piroxicam reactions and to compare immunofluorescence findings in our and other reported drug-induced LABD cases to randomly occurring LABD cases. METHODS Direct and indirect immunofluorescence methods were used to study biopsy and serum samples from both cases and biopsy specimens of 40 other LABD cases. RESULTS Tense blisters developed in two patients medicated with piroxicam. Immunofluorescence studies demonstrated deposits of IgA at the basement membrane zone (BMZ) in case 1 and only non-disease-specific fibrin deposits at the BMZ in case 2. Within 1 month of discontinuation of piroxicam, all lesions were gone in both patients. CONCLUSION In LABD cases proven by direct immunofluorescence, (1) the index of suspicion of drug induction should be higher in cases with only IgA and no IgG in the BMZ; (2) possibly up to two thirds of all LABD cases may be drug induced; and (3) the negative immunofluorescence findings in case 2 and other cases reported in the literature suggest that LABD is one of several host responses in drug-induced blistering diseases.