<prompt> 70-year-old female came with multiple erosion flaccid bulla over skin. Slight rubbing of the skin results in exfoliation of the outermost layer, forming a blister within minutes. Erosions were present over oral mucosa. No target lesion seen. Diagnosis?Pemphigus vulgarisBullous pemphigoidDermatitis herpetiformisSJS  <response>: Ans. a. Pemphigus vulgarisMucosal involvement, nikolsky sign exfoliation of skin on rubbing positive, flaccid bulla with erosions - all are features of pemphigus vulgaris.Target lesions are seen in erythema multiformeMucosal involvement is absent in bullous pemphogoid. 