Usefulness of a Simple Immunohistochemical Staining Technique to Differentiate Anti-p200 Pemphigoid From Other Autoimmune Blistering Diseases: A Report of 2 Cases.

Anti-p200 pemphigoid is a rare autoimmune subepidermal blistering disease characterized by the presence of circulating immunoglobulin G antibodies directed against laminin gamma-1, a 200-kDa protein located in the lamina lucida of the basement membrane. We review the clinical, histopathological and immunological characteristics of the first 2 cases described in Spain. Anti-p200 pemphigoid shares histopathological and immunopathological findings with epidermolysis bullosa acquisita, the main entity in the differential diagnosis. However, its management follows the same guidelines as those used for bullous pemphigoid. The diagnosis is confirmed by immunoblotting, which is a complex technique available in few centers. We propose the immunohistochemical detection of collagen type IV on the floor of the blister, combined with standard immunofluorescence techniques, as a simple, accessible alternative to differentiate anti-p200 pemphigoid from epidermolysis bullosa acquisita.