Dermatitis Herpetiformis
Symptoms
External symptoms are an intense burning and itching rash. The intestinal symptoms of celiac disease may or may not appear. A new, unscratched lesion is red, raised, and usually small in diameter with a tiny blister at the centre. If scratched, crusting appears on the surface. The burning or stinging sensation is different from a regular itch, and can often occur 8–12 hours before a lesion appears.
Causes
Genetic factors, the immune system, and sensitivity to gluten all play a role. DH and celiac disease are related autoimmune disorders that share the same genetic pathways and chromosome features. Both respond to gluten withdrawal from the diet.
Prevalence
DH occurs in 10 cases per 100,000 population and is more common in males. It is rare in children with onset is most frequently in the late second to the fourth decades of life. About 10-15% of patients with celiac disease have DH.
Area Affected
The most common areas are the elbows, knees, buttocks, back of the neck, scalp, and upper back. Facial and hairline lesions are less common. The rash has symmetric distribution. The inside of the mouth is rarely affected.
Diagnosis
DH can be diagnosed with a biopsy taken from skin adjacent to the blisters. Most people with DH have few or no bowel complaints. A small percentage have diarrhea, bloating, bulky stools, or abdominal cramps. They also may have nutritional defiencies.
Diagnosis of DH can only be made by a dermatologist. The dermatologist must obtain a slight skin biopsy from uninvolved skin adjacent to blisters or erosions. If DH is confirmed, small bowel biopsies are not essential as celiac disease is known to coexist with DH.
Management
Treatment is by dapsone and a gluten free diet.
Dapsone (Avlosulfon)
The response is dramatic. Within 24–48 hours, the burning is relieved and the rash starts to disappear. The aim is to use the smallest dose possible to keep the itch and rash under control. Dapsone has no effect on the gut abnormality.
Gluten Free Diet
Elimination of all wheat, rye, and barley and any parts thereof from the diet will result in:
Improvement of skin lesions
The gut returning to normal
Substantial reduction in or elimination of the need for sulphones to control the skin rash
Decreased risk of malignancy
Click here for more about the gluten free diet.