Patient with gluten-sensitive enteropathy has a lifelong history of periodic crops of intensely pruritic, grouped, papular or vesicular lesions on the elbows, knees, sacrum, and shoulders. Because the vesicles are intensely pruritic, the patient routinely scratches the top off them, which relieves the pruritus. Which of the following is the most likely diagnosis?

The condition described is dermatitis herpetiformis, which is strongly associated with gluten-sensitive enteropathy (celiac sprue), and often has a life-long, intermittent course. Clinically, patients have (excoriated) groups of papules and vesicles on an erythematous base. The lesions tend to involve the extensor surfaces of the extremities and the buttocks. Microscopically, the lesions show subepidermal papillary dermal neutrophilic abscesses, with granular deposits of IgA and C3 in dermal papillary tips. Patients may respond dramatically to dapsone therapy. Bullous pemphigoid produces large, tense blisters. Herpes simplex I is characterized by crops of vesicles, but is not paicularly associated with gluten-sensitive enteropathy. Pemphigus vulgaris usually shows prominent oral involvement. Ref: DeWitt C.A., Buescher L.S., Stone S.P. (2012). Chapter 153. Cutaneous Manifestations of Internal Malignant Disease: Cutaneous Paraneoplastic Syndromes. In L.A. Goldsmith, S.I. Katz, B.A. Gilchrest, A.S. Paller, D.J. Leffell, N.A. Dallas (Eds), Fitzpatrick's Dermatology in General Medicine, 8e.