Unique immunobullous disease in a child with a predominantly IgA response to three desmosomal proteins.

We report the case of a 15-year-old girl who presented at 11 years of age with an interesting, acquired and, to our knowledge, unique blistering disease. It involved both skin and mucous membranes with extensive oral and periungual lesions, clinically resembling paraneoplastic pemphigus. Skin biopsy showed an inflammatory cell infiltrate in the upper dermis with numerous leucocytoclastic nuclear fragments, neutrophilic papillary microabscesses and a small subepidermal bulla. Direct and indirect immunofluorescence studies showed marked intercellular staining with IgA and less prominent staining with IgG. Granular deposition of IgA and, to a lesser extent IgG and C3, was also seen along the basement membrane zone. Immunoblotting and enzyme-linked immunosorbent assay studies showed both IgG and IgA antibodies to desmocollin, desmoglein 3 and desmoplakin. However, despite extensive investigation, no underlying neoplasm was found. Treatment with dapsone and sulphapyridine proved ineffective but methylprednisolone and azathioprine have reduced the blistering. We believe that this patient is unique for her combination of IgA and IgG antibodies to desmoplakin, desmocollin and desmoglein 3, although further studies may provide further clarification.