50-year-old female presents with blisters and erosions on the skin and mucous membranes, most commonly inside the mouth. Direct immunofluorescence (DIF) on normal-appearing perilesional skin was done. It shows IgG within suprabasal intercellular spaces-fishnet pattern Diagnosis:

Ans. (a) Pemphigus vulgarisDIF usually shows immunoglobulin G (IgG) deposited on the surface of the keratinocytes in and around lesions giving a fish net pattern. IgG1 and IgG4 are the most common subclasses.Direct immunofluorescence (DIF) is usually done on normal-appearing perilesional skin