Overview
Dermatitis herpetiformis (DH) is the cutaneous manifestation of celiac disease, presenting as intensely pruritic, grouped vesicles on the elbows, knees, buttocks, and scalp. It is driven by IgA antibodies against epidermal transglutaminase (eTG), the skin homolog of tissue transglutaminase (tTG) targeted in celiac disease. Virtually all DH patients have underlying celiac enteropathy, though intestinal symptoms may be subclinical.
Microbiome Associations
DH shares the gut microbiome alterations documented in celiac disease: reduced Bifidobacterium and Lactobacillus, increased Proteobacteria and Bacteroides. The gut-skin axis in DH likely operates through immune-mediated pathways — intestinal dysbiosis promotes systemic inflammation and aberrant IgA production that deposits in dermal papillae. Whether skin-resident microbiome changes contribute to lesion formation remains under investigation.
Metal Associations
The subclinical celiac enteropathy in DH patients impairs absorption of iron, zinc, and selenium through villous atrophy. Iron deficiency is common even without overt anemia. Zinc malabsorption may contribute to impaired wound healing and skin barrier dysfunction. These micronutrient deficiencies compound the immune dysregulation driving the disease.
Associated Conditions
DH clusters with other autoimmune conditions: celiac disease (virtually universal), autoimmune thyroid disease, and type 1 diabetes. This autoimmune clustering suggests shared genetic susceptibility (HLA-DQ2/DQ8) and potentially shared gut microbiome-immune interactions.
Cross-References
- celiac disease — underlying intestinal condition
- iron — malabsorption from enteropathy
- zinc — deficiency and skin barrier
- gut-skin-axis — immune-mediated cross-talk