<prompt> A female presented with a skin lesions all over the body which shows positive bulla spread sign. It is characteristic of:Herpes gestationisBullous pemphigoidPemphigus vulgarisHerpes simplex  <response>: Pemphigus vulgaris is characterized by cutaneous and mucosal blisters. On application of tangential pressure on normal skin results in formation of new bulla Nikolsky sign or if applied to pre-existing bulla results in the spread of bulla bulla spread sign. Cutaneous lesions predominantly present on face, trunk, axillae, groins, and scalp. Ref: Illustrated Synopsis Of Dermatology Sexually Transmitted Diseases By Khanna, 3rd edition, Page 64. 