A 15-year-old girl complains of itchy skin lesions of 6 months in duration. Physical examination reveals numerous wheal-like lesions with small vesicles over her elbows and knees. A skin biopsy demonstrates inflammation in the tips of the dermal papillae and subepidermal vesicles. Which of the following histopathologic findings would provide the best evidence to support a diagnosis of dermatitis herpetiformis in this patient?

Dermatitis herpetiformis is an intensely pruritic cutaneous eruption related to gluten sensitivity, which is characterized by urticaria-like plaques and vesicles over the extensor surfaces of the body. Genetically predisposed patients may develop IgA antibodies to components of gluten in the intestines. The resulting IgA complexes then gain access to the circulation and are deposited in the skin. The release of lysosomal enzymes by inflammatory cells cleaves the epidermis from the dermis. The other choices are not typical histologic findings in dermatitis herpetiformis.Diagnosis: Dermatitis herpetiformis