IgA pemphigus with non-pustular erythematous lesions and IgA antibodies to desmocollins 1 and 2.

IgA pemphigus is a rare variant of pemphigus. IgA pemphigus is subdivided into intraepidermal neutrophilic IgA dermatosis-type (IEN-type), whose target antigen is still an enigma, and subcorneal pustular dermatosis-type, whose target antigen is desmocollin 1 (Dsc1). We report a 56-year-old Japanese male with IgA pemphigus showing atypical erythema. One month after erythema developed, the patient visited his private physician, and was tentatively diagnosed as having erythema multiforme. The patient had been intermittently treated with a low dose of oral prednisolone for a year without benefit before visiting our hospital. Clinical examination revealed irregularly-shaped and partially edematous erythema over the trunk and extremities without mucosal involvement. Neither bullae nor pustules were seen during the course. Direct immunofluorescence showed IgA deposition on cell surfaces of keratinocytes in the upper two thirds of the epidermis. Indirect immunofluorescence of monkey esophagus sections revealed IgA and IgG anti-cell surface antibodies. Our new enzyme-linked immunosorbent assays using eukaryotic recombinant proteins of human Dsc 1-3 detected IgA antibodies to Dsc1 and Dsc2. Although no apparent bullae were observed, the diagnosis of IgA pemphigus was made. Prednisolone 30 mg daily was required to control erythematous lesions. Although the pathomechanism for the unique skin lesion is unknown, the possibility that IgA pemphigus has a prodromal phase and that early administration of low dose prednisolone suppressed the development of pustules or bullae were considered.