<s>[INST] context: Dermatitis herpitiformis Chronic blistering skin disease characterised clinically by intensely pruritic grouped vesicles on a erythematous base. Etiology and pathogenesis: Neutrophilic infiltration in dermal papillae, granular IgA deposition in papillary dermis , gluten sensitive enteropathy. Antibodies to gliadin are present in some patients Associated with HLA-DQ2 and HLA -DQ8. Autoantibodies are formed against epidermal transglutaminase(TGe) forming IgA precipitates at papillary tips. Dermal deposition of circulating immune complexes at the papillary tips and activation of complement leads to bullae formation Clinical feature: Age- most common -20-30years Males>females Onset-acute/gradual Skin lesions-polymorphous lesions-papular, uicarial,vescicular,bullous. Primary lesion: small vesicle on a erythematous edematous base, erythematous papule or uicarial plaque Grouped vesicles in herpetiform manner. Intense itching leading to excoriations and crusts Areas of predilection: elbows , knees, buttocks, scrotum, shoulder, posterior hair line,scalp Symetricall distribution over extensor surfaces Associations- gluten sensitive enteropathy,diabetes mellitus type1, connective tissue disorders, gastric hypochlorhydria,thyroid disease, lymphomas Histopathology: neutrophilic microabcesses at dermal papillary tips Direct immunofluorescence: granular deposits of IgA at dermal papillary tips appears as PICKET FENCE Serological tests: circulating anti endomysial, antireticulin anti tissue trans glutaminase antibodies of IgA type Treatment: Dapsone is the drug of choice. Gluten free diet Otherdrugs- sulfasalazine,colchicine,cyclosporine,azathioprine.,prednisolone. IADVL textbook of dermatology, page 1119 [/INST] question: A 30 year old male had severely ithcy papula vesicular lesions on extremities, knees, elbows and butocks for one year. Direct immunofluorescence staining of the lesions showed IgA deposition at dermal papillary tips. The most probable diagnosis is | options: A: Pemphigus vulgaris B: Bullous pemphigoid C: Dermatitis herpetiformis D: Nummular eczema | answer: C </s>