What is A 35-year-old man has had an outbreak of pruritic lesions over the extensor surfaces of the elbows and knees during the past month. He has a history of malabsorption that requires him to eat a special diet, but he has had no previous skin problems. On physical examination, the lesions are 0.4- to 0.7-cm vesicles. A 3-mm punch biopsy of one of the lesions over the elbow is performed and on microscopic examination shows the accumulation of neutrophils at the tips of dermal papillae and the formation of small blisters caused by separation at the dermo-epidermal junction. Immunofluorescence studies show granular deposits of IgA localized to tips of dermal papillae. Laboratory studies show serum antigliadin antibodies. What is the most likely diagnosis? and explain in detail?
Dermatitis herpetiformis can accompany the celiac disease. The IgA or IgG antibodies formed against the gliadin protein in gluten that is ingested (commonly in wheat, rye, and barley grains) cross-react with reticulin. Reticulin is a component of the anchoring fibrils that attach the epidermal basement membrane to the superficial dermis. This explains the localization of the IgA to the tips of dermal papillae and the site of inflammation. A gluten-free diet may relieve the symptoms. Bullous pemphigoid can occur in older individuals, with an antibody directed at keratinocytes to produce flaccid bullae, but there is no association with celiac disease. Contact dermatitis is most likely to be seen on the hands and forearms. It is a type IV hypersensitivity reaction without immunoglobulin deposition and would not persist for 1 month. Discoid lupus erythematosus is seen in sun-exposed areas and has the appearance of an erythematous rash. Erythema multiforme is a hypersensitivity response to infections and drugs; it produces macules and papules with a red or vesicular center, but it is probably mediated by cytotoxic lymphocytes and not by immunoglobulin deposition. Pemphigus vulgaris is an autoimmune disease in which IgG deposited in acantholytic areas forms vesicles that rupture to form erosions; it is not related to celiac disease.