Eczema refers to any skin inflammation. A type of eczema called dermatitis herpetiformis is an autoimmune disorder characterized by intensely itchy, raised, red rashes and blisters, usually grouped on the extensor surfaces of elbows, knees, buttocks and the back. The condition is closely associated with celiac sprue (also known as gluten-sensitive enteropathy), an autoimmune disease of the intestines acquired with consumption of food that contains gluten, a protein present in barley, rye and wheat.
Cause of Dermatitis Herpetiformis
If you have celiac sprue, stimulation of the intestines with dietary gluten produces immunoglobulin A (IgA) antibodies directed against particular antigens. Evidence indicates that the produced IgA antibodies cross-react with another antigen, called epidermal transglutaminase-3 (eTG), found in maturing skin cells. When IgA and eTG bind, they form a circulating antibody-antigen immune complex that eventually finds its way to the papillary layer of the epidermis, where it is deposited.
Deposited immune complexes recruit white blood cells and activate the complement system in the dermis, causing an immunological cascade that ultimately leads to inflammation of the skin. Dermatitis herpetiformis is a consequence of this immunological and inflammatory reaction. Diagnosis of the condition requires demonstration of these complexes in the papillary dermis of a skin biopsy.
Dermatitis herpetiformis is a rare disease, affecting only about 10 in 100,000 individuals. Because of its association with celiac sprue, incidence of dermatitis herpetiformis is frequently found in northern Europe, where the rate of occurrence of celiac sprue is significant. It appears that if you are a man, you are more prone to having dermatitis herpetiformis, and that the typical onset is during the second to fourth decades of your life.
Both dermatitis herpetiformis and celiac disease have strong genetic components. There is an increased risk if you are positive for HLA-A1, HLA-B8, HLA-DR3 and HLA-DQ2 haplotypes.
Signs and Symptoms
The most common presentation of dermatitis herpetiformis is a waxing and waning crop of pruritic rashes over the extensor surfaces of shoulders, arms, elbows, knees and buttocks. The scalp, face, palms and soles are virtually spared from any lesion.
The colors of rashes range from the natural skin color to red, and may be evenly studded with clusters of small blisters called vesicles. Since rashes are intensely itchy, sometimes with a burning or stinging sensation, it is common to see excoriations due to chronic scratching. Worsening episodes of the disease are associated with intake of gluten from the diet.
Dermatitis herpetiformis is a lifelong disease without any known cure. However, symptoms can be controlled through the use of medications and by avoiding gluten in the diet. While totally eliminating gluten from the diet is very difficult to achieve, merely reducing intake can significantly lessen symptoms. Oats are safe and reasonable alternatives to barley, rye or wheat.
The first-line medications used to treat dermatitis herpetiformis are dapsone and sulfapyridine, and both drugs are effective in controlling symptoms. Other alternatives, albeit less effective, are colchicine, cyclosporine, azathioprine and prednisone. Avoid the use of nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin, indomethacin and naproxen, because these can potentially exacerbate dermatitis herpetiformis.