Extremely pruritic excoriation & papules on buttocks with autoantibodies against epidermal transglutaminase and IgA deposition in dermis on immunohistological examination of normal perilesional skin. Diagnosis is –
Following information suggest the diagnosis of dermatitis herpetiformis.

Extremely pruritic
Paulo - excoriation
Buttock involved
Antibodies against epidermal transglutaminase
IgA deposition in dermis
Pemphigus vulgaris
Pemphigoid
Linear IgA disease
Dermatitis herpetiformis