Immunohistochemistry for immunoglobulin g4 on paraffin sections for the diagnosis of pemphigus.

Context.-Pemphigus is a group of autoimmune vesiculobullous diseases characterized by immunoglobulin G (IgG) antibodies directed against desmosomal adhesion proteins, with IgG4 being the predominant subclass in active diseases. Direct immunofluorescence for IgG performed on fresh-frozen tissue plays a crucial role…