ANSWER
The correct answer is dermatitis herpetiformis (DH; choice “b”).
DISCUSSION
DH is unusual, although not rare, and it is often overlooked in the investigation of itchy rashes—even by dermatologists. As is so often the case, the biopsy was the missing piece of the puzzle, since it clearly showed changes consistent with this condition.
The history of DH has some interesting overlap with that of biopsy. It was Rudolph Virchow, an 18th century Austrian pathologist, who first connected clinical disease to specific arrangements of disordered tissue seen microscopically—at that time, a giant leap for medicine. An American dermatologist, Louis Adolphus Duhring, had the good fortune to study under Virchow and his successors in Vienna and brought this cutting-edge knowledge back to this country, where he began the process of categorizing diseases by their histologic patterns as well as by their presentation and clinical course. This was when he discovered the basis for the condition that became known as Duhring disease, also known as dermatitis herpetiformis.
It was much later (1967) that a connection was made between DH and the ingestion of gluten. Our patient experienced a rapid decline in his itching and rash as soon as he started a gluten-free diet. However, since many patients find such a diet difficult to maintain, there are pharmacologic options as well: dapsone, colchicine, sulfa drugs, drugs from the tetracycline family, and nicotinamide. All have potential adverse effects with which the prescriber needs to become familiar.
With a combination of medication and reduced gluten intake, it’s entirely possible that the patient’s DH will permanently resolve, although he will remain at increased risk for other autoimmune conditions.