This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Skin, Subject name: Pathology
[{'content': '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: \nSelect and explain. \nA. Pemphigus vulgaris, B. Dermatitis herpetiformis, C. Bullous pemphigoid, D. None', 'role': 'user'}, {'content': 'Answer: A \nExplanation: 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', 'role': 'assistant'}]