If you have celiac disease, you may have heard about dermatitis herpetiformis (DH). Dermatitis herpetiformis is a very serious skin disorder that is related to celiac disease. The majority of people with dermatitis herpetiformis are gluten intolerant, although they may not have symptoms and may not know that they have celiac disease.
The rash of dermatitis herpetiformis has a number of specific characteristics:
- It is extremely itchy.
- The first things seen on the skin are red bumps or raised areas, and blisters. The blisters are the most commonly seen part of the rash.
- The rash appears on the elbows and knees, the scalp, back of the neck, the buttocks and the back. It affects other areas much less often.
- It can start at any time, even childhood.
- Most often, DH first appears in people between the ages of 20 and 50 years.
- The disease does not go away spontaneously. It does not respond to the usual creams and lotions prescribed for many skin problems. Sometimes, after someone with this condition has been experiencing the rash and has been scratching, all that can be seen is scratches and red bumps with crusting. Also, it is possible for people with dermatitis herpetiformis to experience burning and or stinging in advance of the appearance of the rash.
Most people with DH share the specific HLA antigens that people with celiac disease have, either HLA-DQ8 or HLA-DQ2 antigens. Dermatitis herpetiformis, like celiac disease, is associated with other autoimmune illnesses including thyroid disease and type 1 diabetes.
The diagnosis of dermatitis herpetiformis can be made by biopsy of the affected skin areas. A special stain must be used. In addition to changes in the skin that occur in any kind of rash with bumps and blisters, there are deposits of IgA visible in a characteristic pattern. Remember, patients are screened for celiac disease with tests measuring specific IgA levels – anti-tissue transaminase and endomysial antibody. It is believed that these IgA antibodies are a part of the dysfunction of the immune system in DH and celiac disease.
There is a treatment for DH, called dapsone, an oral medication that can lead to significant improvement of the rash within 24 to 48 hours. Dapsone can cause side effects, especially at higher doses. Essentially everyone who takes dapsone has some damage to their red blood cells. This needs to be watched closely, and the lowest possible dose must be used. Eating a gluten-free diet can often lower the dose of dapsone needed to control the rash, or even make the medicine unnecessary. This may take years.
Even if someone with DH does not have gastrointestinal symptoms, he or she may have celiac disease. It is worthwhile making the diagnosis of celiac disease before removing gluten from the diet. It may be easier for many people to stay on a gluten-free diet because of something more serious than a rash. Since most of these individuals have positive blood tests, small bowel biopsy is necessary. In addition to a decreased need for dapsone, individuals with DH who do stay on the gluten-free diet also report that they feel better overall.
Dermatitis herpetiformis is clearly a part of the celiac spectrum. It can be diagnosed by biopsy and treated with dapsone. Anyone with DH should be tested for celiac disease and put on a gluten-free diet.