Dermatitis herpetiformis is an autoimmune skin condition characterized by the formation of small, itchy blisters that typically appear on the elbows, forearms, knees, and buttocks.
Although these are the body areas most commonly affected, dermatitis herpetiformis can also affect other areas of the body including the face and scalp.
The rash usually develops bilaterally, in a symmetrical fashion, appearing on both the elbows, for example. When the rash does resolve, there may be pale or brown areas of skin due to loss of pigmentation.
The condition is slightly more common among men than among females.
Celiac Disease and Dermatitis Herpetiformis
Dermatitis herpetiformis is considered to be the skin form of celiac disease and around 15 to 25% of individuals who have celiac disease develop this skin rash.
Celiac disease is a chronic autoimmune condition caused by the immunes system’s reaction to a protein called gluten, found in wheat, rye, and barley.
When a person with celiac disease consumes gluten, the immune system of the small intestine reacts by damaging the gastrointestinal lining.
An antibody called immunoglobulin A (IgA) is produced that collects in tiny blood vessels under the skin and this triggers further immune reactions that lead to the symptoms of dermatitis herpetiformis.
The symptoms of celiac disease can be mild or severe and may include diarrhea, nausea, bloating, fatigue, constipation, weight loss, anemia, and hair loss.
Once a diagnosis of celiac disease is made, the only way to treat the condition is for patients to adhere to a gluten-free diet, at which point, they should start to feel much better.
Only about 20% of individuals who have dermatitis herpetiformis experience the intestinal symptoms of celiac disease, although biopsies have revealed that 80% of these patients do have some degree of intestinal damage, particularly if their diet is rich in gluten.
Diagnosis of Dermatitis Herpetiformis
Dermatitis herpetiformis is diagnosed by taking a biopsy of the top layer of skin, referred to as the dermal papillae. This skin is tested for the presence of neutrophils and IgA deposits.
The diagnosis can also be confirmed by performing the same tests as those used to diagnose celiac disease. A biopsy may be taken from the small intestine and the blood is checked for specific antibodies.
Management of Dermatitis Herpetiformis
Before the link between dermatitis herpetiformis and celiac disease was discovered, dermatitis herpetiformis was treated solely with medication.
Today, although drugs are required to bring the skin rashes under control, the condition can be prevented in the long-term by sticking to a gluten-free diet. Since drugs can improve the skin symptoms within days, it is normal practice for both drugs and the diet to be started together initially.
The gluten-free diet that patients are placed on may have no effect on the rash for around six months and sometimes even longer. It therefore takes this long before drug dosage can be reduced and around two years before the use of drugs can be stopped completely.
Also, patients must remember that adherence to the diet needs to be strict because even tiny amounts of gluten can result in patients being unable to stop taking their drugs.
The drug most commonly used to treat dermatitis herpetiformis is the antibiotic dapsone. Generally, dapsone significantly relieves symptoms such as burning and itching within just 1 to 3 days. Patients who do not tolerate dapsone may be given sulfapyridine or sulfasalazine, although these are relatively less effective.