Dermatitis herpetiformis is an autoimmune disease that is closely linked to coeliac disease. In autoimmune diseases, the immune system recognises the body’s own tissues as foreign and mounts a response against them, causing damage to the tissues. Despite the name of the disorder, it is not caused by the Herpes virus and has no association with the herpes virus. The name herpetiformis came about because the skin rash looks similar to rashes that are due to the herpes virus. The disease affects more men than women; approximately 2/3 of patients with the disorder are males. In most people, dermatitis herpetiformis tends to occur in early to middle adulthood. Genetics are important in the cause of the disease, and a few important genes have been identified. Much like coeliac disease, dermatitis herpetiformis involves intolerance to gluten.
Signs & Symptoms
The main feature of dermatitis herpetiformis are very itchy bumps (papules) and blisters on the skin. There may also be feelings of burning or stinging. The underlying skin may look normal, or be red and inflamed. When scratched, the blisters often appear crusty. Old blisters may leave markings on the skin, which may be lighter or darker than the normal skin colour. Dermatitis herpetiformis is generally symmetrical (affects both sides of the body similarly), and the lesion are most commonly found on the scalp, elbows, knees, shoulders and buttocks. It does not usually affect the face or the back of the scalp. Although not common, some patients may get lesions in the inside of their mouth. Sometimes there are also bleeding spots on the skin of the fingers.
The majority of patients with dermatitis herpetiformis also have coeliac disease, and it may be thought of as the skin manifestation of coeliac disease. Because of this association, patients may also have some of the symptoms and signs of this disease, which include:
- Abdominal discomfort
- Weight loss
Tests & Investigations
The most important test to confirm a diagnosis of dermatitis herpetiformis is a biopsy of the skin. This is a minor procedure in which a sample of the affected skin is taken and sent to the laboratory for testing and analysis. A blood test may also be ordered to look for some of the antibodies that are associated with coeliac disease.
The most effective treatment for dermatitis herpetiformis is a medication called dapsone. Dapsone was initially used as an antibiotic to treat leprosy. Although it does work as an antibiotic, this is not the main mechanism of action for dapsone in dermatitis herpetiformis. Dapsone also has anti-inflammatory properties and can also help to control the effects of the immune system, which are more important in the treatment of this disorder. It can be used as a topical cream or in tablet form. Some potential side effects of dapsone include nausea, vomiting, diarrhoea, skin irritation and haemolytic anaemia. A small number of patients who are treated with dapsone develop a dapsone hypersensitivity syndrome, which involves a rash, jaundice and fever. It may take up to six weeks to develop. This can potentially be fatal. Treatment involves immediately stopping dapsone therapy and giving systemic corticosteroids.
If patients do not tolerate dapsone, there are other potential therapies but these are not as effective. One treatment option is corticosteroids, which can be used topically or orally. However, there are numerous side effects associated with corticosteroids, particularly with long term use. Some side effects include thinning of the skin, skin bruising and weight gain. Other possible medications include colchicine, a medication most commonly used to treat gout and cyclosporine, which is a drug used to suppress the activity of the immune system.