A case of linear IgA disease in a child with IgA and IgG circulating antibodies directed to BPAg2

A 7-year-old Caucasian girl had multiple bullae on the trunk, upper and lower limbs (Fig. 1a,b) for 10 days. The lesions were large, tense, and asymptomatic, and mucosae were not involved. Laboratory findings were all normal. Histopathology revealed a subepidermal blister containing numerous neutrophils, eosinophils, and fibrin. Direct immunofluorescence of perilesional skin disclosed linear deposition of IgA and slight linear deposits of IgM at the basement membrane zone (Fig. 2). Indirect immunofluorescence on monkey esophagus and on human salt-split skin was negative. Immunoblot assay (IB), performed with an epidermal extract, revealed IgA and IgG antibodies directed to BPAg2 antigen (Fig. 3), while it was negative when performed on dermal extract. Enzyme-linked immunosorbent serologic assay using a commercial kit (MBL, Naka-Ku Nagoya, Japan) with the noncollagenous domain (NC16A) of the BPAg2 antigen was negative for both IgA and IgG. A diagnosis of linear IgA disease (LAD) was made and a treatment with dapsone (50 mg/day) and prednisolone (30 mg/day) was initiated. One month later, lesions had cleared.