The patient’s history of celiac disease and the presence of vesicular lesions affecting primarily extensor surfaces pointed to a diagnosis of dermatitis herpetiformis (DH).
DH is an autoimmune skin condition that is associated with gluten sensitivity. It is more frequent in individuals of northern European heritage.1
The lesions associated with DH are intensely pruritic grouped papules, vesicles, and tense blisters that appear more commonly on extensor areas of the lower limbs, elbows, buttocks, and sacral region. Involvement of the oral mucosa is rare and not all patients with DH experience the intestinal symptoms of gluten sensitivity.
Direct immunofluorescence of perilesional skin is the gold standard to confirm the diagnosis. Histology of the lesions is also performed, but findings may vary depending on the age of the lesion. Additionally, serology can help to confirm the diagnosis. Both tissue and epidermal transglutaminase antibodies are often present in the serum but may be negative if the patient is following a gluten-free diet. In this case, biopsy was not ordered because the patient already had a biopsy-confirmed diagnosis of celiac disease and a classic presentation of lesions.
Treatment of DH consists of a strict gluten-free diet and dapsone as first-line pharmacologic therapy. Typically, dapsone is started at doses of 25 to 50 mg daily and increased, as needed and tolerated, to 100 to 200 mg per day. Improvement is usually seen within 2 days of treatment initiation. Dapsone has multiple potential adverse effects; the most common is hemolysis. Since individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency can develop severe hemolysis if treated with dapsone, it is necessary to screen for this condition prior to initiation of treatment. A complete blood count and liver and renal function testing are typically done before, and during, treatment with dapsone.1
This patient had normal levels of G6PD and his screening labs were also normal. He was started on dapsone orally 25 mg/d and follow-up was pending.
Image courtesy of Daniel Stulberg, MD. Text courtesy of Marcella Colom, MD, and Daniel Stulberg, MD, FAAFP, Department of Family and Community Medicine, University of New Mexico School of Medicine, Albuquerque.