dermatitis herpetiformis
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The skin form of gluten sensitivity — a blistering rash that is pathognomonic for celiac-spectrum disease and resolves on a gluten-free diet.
Dermatitis herpetiformis is a chronic blistering skin condition caused by IgA antibody deposits in the skin. It is the cutaneous (skin) manifestation of gluten sensitivity and shares the same underlying immunological mechanism as intestinal celiac disease — the same anti-tTG antibodies responsible for gut damage also deposit in the skin, where they cause the inflammatory reaction.
Why It Happens
tissue-transglutaminase is expressed not only in the gut but also in skin tissue. Anti-tTG IgA antibodies circulating in the blood can deposit in the papillary dermis (the upper layer of skin), triggering an inflammatory reaction that causes the characteristic blistering.
Clinical Features
- Intensely itchy, symmetrical blistering rash
- Characteristic sites: elbows, knees, buttocks, scalp, back of neck
- Blisters are small, grouped (herpetiform = resembling herpes blisters in distribution pattern, not caused by herpes virus)
- Chronic and relapsing if gluten exposure continues
- Often excoriated (scratched open) before a patient seeks care, making the blisters harder to find
Diagnosis
DH is diagnosed by skin biopsy with direct immunofluorescence — showing granular IgA deposits in the papillary dermis. This pattern is pathognomonic for DH and therefore for gluten sensitivity. Blood TTG IgA is usually positive.
Importantly, patients with DH may have minimal or no GI symptoms — the skin can be the dominant or sole manifestation. Intestinal biopsy may still show subclinical villous-atrophy or elevated IELs.
Treatment
- gluten-free-diet — first-line; resolves the rash over months as antibody levels fall
- Dapsone — a medication that rapidly suppresses the skin inflammation while the GFD takes effect; does not treat the underlying celiac disease
Relationship to Celiac Disease
DH is considered a variant of celiac disease, not a separate condition. Patients with DH have the same HLA-DQ2/DQ8 genetic risk factors and the same long-term complication profile (including EATL risk, bone disease, etc.) as intestinal celiac patients.
Related Concepts
autoantibodies-celiac | tissue-transglutaminase | gluten-free-diet | iga-and-iga-deficiency | hla-dq2-dq8 | villous-atrophy | eatl