<prompt> 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:Pemphigus vulgarisDermatitis herpetiformisBullous pemphigoidNone  <response>: 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 