Ans. b. Dermatitis herpetiformis Granular deposition of IgA at dermal papillae on immunofluorescence is seen in dermatitis herpetiformis.Dermatitis Herpetiformis: Diagnosis is confirmed by direct immunofluorescence microscopy of normal appearing or faintly erythematous perilesional skin (adjacent to active lesion), by demonstration of granular deposits of IgA (with or without complements) in papillary dermis** and along the epidermal basement membrane zone (EBMZ)."Dermatitis Herpetiformis (Duhring Disease)* Associated with Subclinical gluten sensitive enteropathy^* Associated with HLA-B8 (60%)/DRW3 (95%) and HLA-DQW2 haplotype (95-100%)* Increased incidence of autoimmune disorders e.g. thyroid abnormalities (mostly hypothyroid), achlorhydria, atrophic gastritis, and antigastric parietal cell antibodies, insulin dependent DM. SLE, Sjogren syndrome, vitiligo, RA. UC, myasthenia and gastrointestinal non Hodgkins Lymphoma.* Dietary gluten sensitivity in DH is associated with IgA endomysial autoantibodies that target tissue transglutaminase.* On direct immunofluorescence, IgA autoantibodies against epidermal transglutaminase and granular deposits of IgA in papillary dermis (dermal papillae),Dermatitis Herpetiformis (Duhring Disease)Clinical Feature:* Most common in 2nd- 4th decade* Intensely (itchy) pruritic0. papulovesicular/urticarial skin ds characterized by lesions symmetrically distributed over extensor surfaces (i.e. elbows, knees, buttocks, back, scalp and posterior neck)0* Primary lesion is a papule, papulovesicles or urticarial plaque.* Because pruritus is prominent, patients may present with excoriation and crusted papules with no observable primary lesion0.* Pruritus may have a distinctive burning or stinging component.Diagnosis:* Lesion biopsy reveal subepidermal blister with neutrophils in dermal papillae i.e. subepidermal bullae with papillary tip abscess0* Diagnosis is confirmed by direct immunofluorescence microscopy of normal appearing or faintly erythematous perilesional skin (adjacent to active lesion), by demonstration of granular deposits of IgA (with or without complements) in papillary dermis0and along the epidermal basement membrane zone (EBMZ)Treatment:* IgA deposits in skin are unaffected by control of disease w ith medication dapsone; but decrease or disappear in patients maintained on long periods on a strict gluten-free diet (treatment of choice).Dapsone (diaminodiphenvlsulfone: Drug of choice), sulfoxone (diasone) and sulfapyridine control but do not cure disease.* Elemental diet (composed of free amino acids, short chain polysaccharides and small amount of triglycerides) without full proteins can alleviate skin disease within few weeks.* Atkins diet with high protein, unlimited fat and low carbohy drate also lead to complete resolution of skin disease