Dermatitis Herpetiformis
It is a sub-epidermal blistering disorder.
Pathogenesis:
⁃ It occurs due to IgA autoimmune against epidermal transglutaminase (eTG).
⁃ Genetic causes and dietary factors (presence of dietary gluten and its constituent gliadin) results in formation of IgA, which reacts with eTG in skin (leads to formation of blisters) and tissue TG or tTG in small intestine (leads to gluten-sensitive enteropathy or celiac disease)
Clinical findings:
⁃ Patient presents with chronic, intensely itchy, grouped papules and vesicles, distributed symmetrically on extensors like elbows, knees, buttocks, shoulders and sacral areas.
⁃ There may be history of diarrhoea (due to celiac disease)
Investigations :
⁃ Biospy : subepidermal split and neutrophils on tip of dermal papillae
⁃ DIF: Granular of fibrillar IgA deposits in the papillary dermis
Treatment :
⁃ Gluten free diet (Avoid Barley, Rye, Oat, Wheat)
⁃ Dapsone
⁃ Other sulfa drugs