Dermatitis herpetiformis (DH) is a relatively rare skin disorder with an 
estimated incidence of 1:10,000 in the UK. It is characterized by urticarial 
plaques and blisters on the elbows, buttocks, and knees, although other sites 
may also be involved. The eruption tends to be persistent: only 10-15% of 
patients have spontaneous remission over a 25-year study period. The disease is 
characterized by the presence of IgA deposits in the upper dermis of uninvolved 
skin and the diagnosis should not be made in the absence of these deposits. 
Two-thirds of patients have a small intestinal enteropathy with villous atrophy 
as seen in coeliac disease (CD). However, the remaining third also show evidence 
of a gluten sensitivity in the intestine, as judged by increased lymphocytic 
infiltration of the epithelium. Villous atrophy also ensues after gluten 
challenge in those patients with previous normal villous architecture. The 
initial treatment of the rash is with one of the following three drugs, dapsone, 
sulphapyridine or sulphamethoxypyridazine. However, the rash also clears with 
gluten withdrawal. It must be stressed, however, that the average time to 
achieve significant reduction in drug requirements is 6 months and it can be 
over 2 years before drugs are no longer required. On re-introduction of gluten 
the eruption recurs. Patients with DH have a high incidence of auto-immune 
disorders, thyroid disease, pernicious anaemia, and insulin-dependent diabetes, 
and should be screened for those diseases on a yearly basis. As with coeliac 
disease there is also an increased incidence of lymphoma and a gluten-free diet 
appears to protect patients from this complication. The mechanism by which 
gluten causes the skin lesions has still to be elucidated, but current 
investigations implicate lymphocytes and cytokines in the pathogenesis. The 
original hypothesis of an antigen-antibody reaction in the skin with complement 
activation causing the skin lesions, may not be correct.