This 74-year-old woman presented with pruritus and clusters of small vesicles on her elbows. She also had a long history of celiac sprue. This is a typical example of dermatitis herpetiformis, with the exception of the patient's age. Pruritus, symmetrically clustered vesicles, and gluten-sensitive enteropathy are all commonly seen. These patients may improve on a gluten-free diet. The histopathology is fairly typical in this case. The usual blister cavity is not present, but neutrophils predominate as the infiltrate, and classically aggregate in the dermal papillae. The differential diagnosis includes linear IgA (usually more confluent than clulstered) and other subepidermal vesicobullous disorders. The diagnosis in confirmed in this case by visualizing the granular IgA deposition in the tips of dermal papillae on direct immunofluorescence.
At higher power of the same lesion, one can appreciate the aggregates of neutrophils within the dermal papillae. There is focal collagen breakdown and the beginnings of a subepidermal cleft.