What is the “Celiac Rash” AKA Dermatitis Herpetiformis?
You may be wondering why the skin is involved and not solely gastrointestinal symptoms when it comes to celiac disease. This is because the mucosal immune system in the intestine responds by producing IgA antibodies, and these IgA antibodies are directed against epidermal transglutaminase. They travel to the skin and bind with the epidermal transglutaminase protein, a reaction in which gluten ingestion seems to trigger. DH patients frequently do not have digestive symptoms.
Dermatitis Herpetiformis (DH), is also known as Duhring’s disease. It is a chronic skin condition caused by a reaction to gluten ingestion. It is characterized by extremely itchy bumps or blisters. DH affects 10-15% of people with celiac disease. They are most often on the forearms near the elbows, knees, buttocks and along the hairline. Because the bumps and blisters resemble herpes lesions, it is named herpetiformis, but they are not caused by the herpes virus. They are caused by gluten ingestion.
Surprisingly, 20% of people with DH will have a normal intestinal biopsy, but patients with DH are at the same risk for complications suffered by people with celiac disease. People of all ages are affected by DH but it most often appears for the first time in people between the ages of 30 and 40. Northern European descent individuals are more likely to develop DH than those of African or Asian heritage. DH is also somewhat more common in men than women.
Doctors diagnose DH by examining the cells under the top layer of skin (dermal papillae), for neutrophils and granular IgA deposits in the skin by taking a biopsy of the skin. This should always be done by someone who has diagnosed this skin condition before and knows how to correctly do the biopsy. If antibody tests are positive and the skin biopsy has the typical findings of DH, patients do not need an intestinal biopsy to confirm the diagnosis of celiac disease.
Treatment is the same, a 100% gluten-free diet. Your dermatologist may prescribe Dapsone, a medication that can provide short-term relief from itching. Usually DH responds within 48 to 72 hours to this medication. Regardless of Dapsone use, a strict gluten-free diet is necessary and it can take about six months to achieve some improvement in DH symptoms and up to two years+ to get total control through a gluten-free diet alone. Your dermatologist may prescribe Dapsone, a medication that can provide short-term relief from itching. Usually DH responds within 48 to 72 hours to this medication.
DH patients with a normal intestinal biopsy and normal celiac blood tests will still respond to a gluten-free diet. DH is commonly diagnosed as eczema and symptoms tend to come and go. With a 100% gluten-free diet, symptoms normally resolve.
