Dermatitis herpetiformis (DH) is a skin disorder often associated with celiac disease. (DH) is an intensely itchy skin eruption. Dermatitis herpetiformis usually begins in persons age 20 and older, although children may sometimes be affected. It is seen in both men and women. It usually shows up in young adults, and is more common in men and people originally from some areas of northern Europe. It has been hypothesized that DH is the result of an immunologic response to chronic stimulation of the gut mucosa by dietary gluten with subsequent activation of cutaneous endothelial cells and circulating inflammatory cells, including neutrophils. DH was formerly described in the literature as Duhring’s Disease. Several chemicals have been associated with induction of DH, including potassium iodide and cleaning solutions. It has a typical onset in the teens or in the third or fourth decades of life. In the U.S., the presence of diagnosed cases is estimated to be about 1 in 10,000 with a male/female ratio of 2:1. It is more common in whites and rare in people of African or Asian descent. If you have DH, you always have gluten intolerance. With DH, the primary lesion is on the skin, whereas with celiac disease the lesions are in the small intestine.
Symptoms of dermatitis herpetiformis are intense burning, stinging and itching around the elbows, knees, scalp, buttocks and back. More locations can also be affected and the severity can vary. Scratching will further irritate the eruptions. Eruptions commonly occur on pressure points, such as around the elbows, the front of the knees, the buttocks, back face, and scalp but can appear anywhere on the body. Eruptions are usually bilateral – occurring on both sides of the body. Ingestion of gluten plays a role in the exacerbation of skin lesions. Small blisters usually develop gradually, mostly on the elbows, knees, buttocks, lower back, and back of the head. Sometimes blisters break out on the face and neck. 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. The fact that the rash is most prevalent at pressure points (where clothing rubs the most) may be why the symptoms sometimes appear to be symmetrical. Typically, the onset of DH is in the second to fourth decade; however, persons of any age may be affected.
Dermatitis herpetiformis is frequently associated with gluten (a protein found in cereals) sensitivity in the small bowel. This means that instead of being highly convoluted, the lining of the intestines is smooth and flattened. Gluten is a protein present in grasses of the species Triticeae, which includes barley, rye, and wheat. Rice and oats belong to different species and are generally well tolerated. Hormonal factors may also play a role in the pathogenesis of DH. Androgens have a suppressive effect on immune activity, including decreased autoimmunity, and androgen deficient states may be a potential trigger for DH exacerbation. IgA circulating immune complexes are present in 25-35% of patients with DH, although no association with disease severity has been noted. These immune complexes also have been noted in patients with isolated GSE and are believed to be related to the presence of the gut disease. Associated autoimmune diseases include dermatomyositis, type 1 diabetes mellitus, myasthenia gravis, rheumatoid arthritis, Sjögren syndrome, systemic lupus erythematosus, and thyroid abnormalities. Thyroid abnormalities are present in as many as 50% of DH patients and include hypothyroidism, hyperthyroidism, thyroid nodules, and thyroid cancer.Gastric manipulation (surgery) may induce DH.
There is a very effective treatment available for dermatitis herpetiformis. A gluten-free diet is very difficult to achieve; however, limiting intake of wheat, barley, or rye products can lessen the symptoms. Dapsone can be associated with severe hematologic (blood) disturbances and must be closely monitored. However, strict long-term avoidance of dietary gluten has been shown to reduce the dose of dapsone required to control the disease and may even eliminate the need for medication. In addition, a gluten-free diet may reduce the risk of gastrointestinal lymphoma. Other, less effective treatments for DH include colchicine, cyclosporine, azathioprine, and prednisone. UV light may provide some symptomatic relief. Cyclosporine should be used with caution in patients with DH because of a potential increase in the risk of developing intestinal lymphomas. Nonsteroidal anti-inflammatory drugs may exacerbate DH; however, ibuprofen appears to be safe. Gulphapyridine or sulphamethoxypyridazine have been used to suppress the skin manifestation. It takes several months for the skin to improve on these drugs and they do not protect against the serious complication of gluten hypersensitivity.