Rapid response of IgA pemphigus of subcorneal pustular dermatosis type to treatment with isotretinoin

Diagnosing IgA pemphigus and distinguishing between its 2 subtypes, intraep idermal neutrophilic IgA dermatosis type and subcorneal pustular dermatosis type, is important because treatment of IgA pemphigus has to be different from treatment of other blistering autoimmune dermatoses. We present a pati ent with subcorneal pustular dermatosis type of IgA pemphigus who rapidly r esponded to systemic treatment with isotretinoin. Specific diagnosis was es tablished by detecting IgA serum activity to desmocollin 1 by indirect immu nofluorescence microscopy on unfixed COS7 cells transfected with desmocolli n 1. No IgA or IgG serum reactivity was found to recombinant forms of desmo gleins 1 and 3 by an antigen-specific enzyme-linked immunosorbent assay The disease was not effectively controlled by conventional therapeutic regimen s. Systemic treatment with isotretinoin 20 mg daily led to complete clearan ce of skin lesions within 3 weeks. Assaying IgA serum reactivity to desmoco llin 1, desmoglein 1, and desmoglein 3 as a valuable method for establishin g the diagnosis and differentiating the 2 subtypes of IgA pemghigus. Isotre tinoin was an effective drug in the treatment of subcorneal pustular dermat osis type of IgA pemphigus in this patient.