Dermatitis Herpetiformis is a very itchy skin rash. It usually effects the outer aspects of the elbow and the knees, across the shoulders and over the buttocks. In very severe cases the rash may be more widespread, and in mild cases confined to the elbows or shoulders alone.
Each little spot goes through four stages:
- A small itchy flat red patch about 2-3mm in diameter
- The flat area becomes thickened and a bump develops above the level of the surrounding normal skin.
- The centre of the bump degenerates and fills with a clear pale yellow fluid (looks like a tiny water blister).
- The fluid is absorbed and a tiny scar is left in the skin.
Stage 3 is not often seen, as the sufferer has usually scratched the spot so much that the surface is broken and the fluid is never able to collect in the blister.
The little blisters look like the rash of Chicken Pox and Shingles, but unlike these two conditions Dermatitis Herpetiformis is neither infective or contagious. In Chicken Pox and Shingles a virus causes the problem and the latin name for the virus is Varicella/Herpes Zoster virus. When doctors started naming rashes they used latin words. The term dermatitis herpetiformis means a skin problem (DERMATITIS) which looks like Chicken Pox (HERPETIFORMIS).
Dermatitis Herpetiformis and Coeliac Disease
There is a strong link between Dermatitis Herpetiformis and Coeliac Disease. It has been discovered that over half of all patients with Dermatitis Herpetiformis have the same intestinal abnormality with damage to the villi on biopsy as do coeliacs. In a further third of the remaining patients there are signs of slight damage to the intestinal biopsy. The gut abnormality whether slight or more severe corrects itself when gluten is excluded from the diet.
Treatment of Dermatitis Herpetiformis
In the vast majority of patients the skin rash responds dramatically within 12-48 hours of treatment with dapsone tablets, but unfortunately when this treatment is stopped the itch and the rash tend to reappear.
All Dermatitis Herpetiformis patients with intestinal damage respond to treatment with a gluten-free diet. Over a period of weeks or months the dose of dapsone required to control the rash may be decreased and in the majority of patients eventually no tablets are required. Even those patients with no signs of inflammation in the intestine benefit from gluten-free diet. It is thought that the skin damage is something to do with gluten antibodies. As with coeliac disease, the diet has to be continued for life or the intestinal damage will recur and the skin rash relapse