A patient presents with persistent painful oral lesions

Pemphigus is a group of chronic, autoimmune blistering diseases of the skin and mucous membrane charecterised histologically by intra-epidermal bullae. Two major types are P.vulgaris and P.foliaceous. P.vulgaris: Target antigens- desmoglein 1 and 3. skin and mucosa are affected. Skin involvement stas in the form of flaccid blisters which easily ruptures producing charecteristic erosions that have no tendency to heal. skin lesions are usually preceded by blisters and erosions of oral mucosa which are very painful and interfere in food intake. Nikolsky sign and bulla spread sign are positive. Nikolsky sign: development of erosion on surrounding normal skin following shearing force. Bulla spread sign: lateral finger pressure at the edge of lesion leads to spread of bulla. P.foliaceous Target antigen: desmoglein 1 Mucosal involvement is absent. Skin involvement is very superficial and flaccid blisters are seen which rupture easily leading to crusted eroded areas. Common sites involved are seborrheic areas like scalp, face, upper trunk and abdomen. Endemic in some pas of brazil and is known as Fogo Selvagum. Ref Harrison 20th edition pg 1233