Overlap of IgA Pemphigus and Linear IgA Dermatosis in a Patient with Ulcerative Colitis: A Mere Coincidence?

Abstract

IgA pemphigus and linear IgA dermatosis (LAD) are rare autoimmune bullous disorders characterized by intraepidermal or dermo-epidermal IgA deposition and blister formation, respectively. IgA pemphigus is divi-ded into different subgroups according to clinical and histological findings: a subcorneal pustular dermatosis (SPD) type and an intraepidermal neutrophilic (IEN) type (1–3). The latter is clinically characterized by flac-cid vesiculopustules forming annular lesions with central crusts, often appearing as “sunflower-like” lesions. Direct immunofluorescence demonstrates intercellular IgA de-position throughout the epidermis. Patients with the SPD type often display circulating autoantibodies of the IgA class against the desmosomal protein desmocollin 1, in contrast to IgA autoantibodies to heterogeneous antigens including desmoglein 1 or 3 in patients with the IEN type of IgA pemphigus. The subepidermal bullous dermatosis LAD presents with annular tense blisters with a “crown of jewels-like” pattern, linear IgA deposition at the ba-sement membrane zone, and circulating autoantibodies that most frequently target the soluble BP180/collagen XVII ectodomain (4). In contrast to the more common eosinophil-rich autoimmune blistering dermatoses pem -phigus vulgaris and bullous pemphigoid, the development of IgA pemphigus and LAD is based on IgA deposition in the skin, which results in neutrophil chemotaxis and subsequent blister formation (5). CASE REPORT