Dermatitis herpetiformis (DH) is a chronic skin condition associated with coeliac disease. It is intensely itchy, even in the presence of a mild rash.
The name, dermatitis herpetiformis, is a descriptive name. The rash is not related to either dermatitis or herpes, but is a specific chronic skin condition.
DH has a genetic basis and is not contagious. The rash may be small lumps, like insect bites (papules), some with tiny fluid filled blisters on top. These small blisters are called vesicles. However it can also appear hive-like, persisting in one area, or it may look like a pink and scaly dermatitis.
DH can flare and subside even without treatment. The rash has a characteristic distribution, over the knee caps, on the outer surface of the elbows, on the buttock area, around the ears, the shoulder blades, and in the hairline and eyebrows. It tends to appear symmetrically on both the left and right sides of the body. When the rash subsides, which often occurs spontaneously, it may leave brown pigmentation or pale areas, where pigmentation is lost.
Who gets Dermatitis Herpetiformis?
People are born with a genetic predisposition to develop coeliac disease and/or DH. DH is slightly more common in males than females and generally presents in adult life (15-55 years). It is uncommon to see DH in children, but it can occur.
Less than 10% of patients with DH have gastrointestinal symptoms suggestive of coeliac disease. However biopsies show that the majority of people with DH have some degree small bowel damage characteristic of coeliac disease. Recent findings confirm that all patients with DH will display villous atrophy on consumption of a high gluten load. There is a small group of patients with coeliac disease who develop DH even though they have been on a strict gluten free diet for years.
Like coeliac disease, it is unclear why the condition develops at a particular time. Both genetic and environmental factors play important roles in DH.
How is the Condition Diagnosed?
The variable presentation of the rash can make diagnosis very difficult, and a referral to a skin specialist (dermatologist) is required. When your doctor suspects DH, a skin biopsy is taken to confirm the diagnosis.
How is the Condition Treated?
DH is treated in the same way as coeliac disease: By maintaining a diet free of gluten for life. It may take six months to achieve moderate improvement in the skin condition and up to two years or more to achieve total control by diet alone.
An oral medication called Dapsone is available to relieve the rash of DH. Dapsone, however, does not improve small bowel damage. Dapsone is generally well tolerated but requires careful medical supervision. It has a number of side effects, especially if taken in large amounts for long periods of time. Sulphapyridine and other sulphonamides can also be used. Maintaining a strict gluten free diet is essential to reducing and eliminating the use of medication.