From the Guidelines
Dermatitis herpetiformis is primarily caused by an autoimmune reaction to gluten, specifically sensitivity to gluten found in wheat, barley, and rye, as evidenced by studies showing a strong link between dermatitis herpetiformis and celiac disease 1.
Causes of Dermatitis Herpetiformis
The condition is characterized by an immune system reaction to gluten, leading to the production of antibodies (IgA) that deposit in the skin, triggering an inflammatory response and resulting in a itchy, blistering rash.
- The rash typically appears symmetrically on the elbows, knees, buttocks, back, and scalp.
- Approximately 85-90% of people with dermatitis herpetiformis also have celiac disease, even if they don't experience digestive symptoms, as noted in studies examining the relationship between celiac disease and dermatitis herpetiformis 1.
Treatment and Management
Treatment involves a strict gluten-free diet, which can take several months to fully control symptoms, along with medications like dapsone to provide faster relief of symptoms.
- Dapsone works by inhibiting neutrophil function and reducing inflammation, but requires regular blood monitoring due to potential side effects.
- Some patients may need to continue medication for 1-2 years while maintaining a gluten-free diet, though the diet must be lifelong to prevent recurrence of the condition.
Key Considerations
Recent studies suggest that wheat starch is a safe and well-tolerated addition to the gluten-free diet when the diet is otherwise strict, as found in a study by Kaukinen et al 1.
- However, it is essential to prioritize a strict gluten-free diet to manage dermatitis herpetiformis effectively, given the strong link between gluten sensitivity and the condition.
From the Research
Causes of Dermatitis Herpetiformis (DH)
- DH is an autoimmune, pleiomorphic, papulovesicular disorder associated with celiac disease and gluten sensitivity 2, 3, 4, 5, 6
- The condition is caused by gluten sensitivity and affects the skin, with symptoms including a symmetrical blistering rash on the extensor surfaces with severe pruritus 3
- DH is characterized by subepidermal bullae on hematoxylin and eosin staining and granular immunoglobulin A deposits in the dermal papillae using the direct immunofluorescence method 2
- The autoantigen in coeliac disease is tissue transglutaminase (TG2), while in DH it is epidermal transglutaminase (TG3) 4
- Both diseases exhibit TG2-specific autoantibodies in serum and small bowel mucosa; patients with DH have IgA-TG3 in the skin 4
Genetic and Environmental Factors
- DH and coeliac disease are strictly associated with class II HLA alleles A10501 and B102 encoding the HLA-DQ2 heterodimer 5
- Coeliac disease segregates in the families of patients with DH, also supporting a shared genetic background 5
- Environmental, not genetic, factors seem to be responsible for the development of the rash in DH, as shown by monozygotic twins with one having DH and the other having coeliac disease 5
Pathophysiology
- The physiopathology of DH is complex, occurring in HLA DQ2 or DQ8 predisposed patients, and implies gluten, immunological reaction in the intestinal wall then in the skin 6
- A clinically silent but immunologically active coeliac disease in the gut could well produce IgA autoantibodies which react also with the connective tissue in the skin 5