Gluten challenge induces skin and small bowel relapse in long-term gluten-free diet-treated dermatitis herpetiformis

Abstract Dermatitis herpetiformis (DH) is an extra-intestinal manifestation of coeliac disease causing an itchy, blistering rash. Skin IgA deposits are pathognomonic for DH, and the treatment of choice is a life-long gluten-free diet (GFD). Preliminary evidence suggests that there are DH patients who redevelop gluten tolerance after adherence to a GFD treatment. To examine this, we performed a 12-month gluten challenge with skin and small bowel mucosal biopsies in 19 DH patients who had adhered to a GFD for a mean of 23 years. Pre-challenge biopsies showed negative skin IgA and transglutaminase 3 deposits in 16 (84%) patients and normal villous height crypt depth ratios in the small bowel mucosa in all 19 patients. The gluten challenge caused a relapse of the rash in 15 (79%) patients in a mean of 5.6 months; 13 of these patients had skin IgA and transglutaminase 3 deposits, and 12 had small bowel villous atrophy. In addition, three patients without rash or skin immune deposits developed villous atrophy, while one patient persisted without any signs of relapse. In conclusion, 95% of the DH patients were unable to tolerate gluten even after long-term adherence to a GFD. Therefore, life-long GFD treatment remains justified in all DH patients.