A female presented with a skin lesions all over the body which shows positive 'bulla spread sign'. It is characteristic of:
Herpes gestationis
Bullous pemphigoid
Pemphigus vulgaris
Herpes simplex
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.