Celiac disease & Dermatitis herpetiformis

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Introduction:

  • Celiac disease = Gluten sensitive enteropathy
  • Foods containing gluten (Mnemonic – BROW):
  1. B: Barley
  2. R: Rye
  3. O: Oat
  4. W: Wheat.
  • Associated with HLA-DQ2 (90%) & DQ8 (10%)
  • 10% of all Celiac disease patients have Dermatitis herpetiformis
  • 70-100% of Dermatitis herpetiformis patients have Celiac disease.

 

Pathophysiology:

  • Main component responsible: Alcohol-soluble fraction of gluten – Gliadin
  • Pathophysiology of Celiac disease: Gluten diet → Gliadin peptide → Activation and proliferation of CD8+ intraepithelial lymphocytes (IEL) → Destruction of enterocytes → Villous atrophy.

  • Pathophysiology of Dermatitis herpetiformis:
    • Gluten diet → IgA antibody against gluten → Molecular mimicry → Cross react with epidermal transglutaminase (TTG) which are present in the papillary tip → Neutrophilic reaction in the papillary tip → Papillary tip microabscess + Papillary tip blister.

Site of involvement & clinical features:

Celiac disease:

  • Duodenum & jejunum are mostly affected
  • Duodenum involved:
  1. ↓Ca absorption: Hypocalcemia
  2. ↓Fe absorption: Recurrent iron deficiency anemia
  • Jejunum involved:
  1. ↓Folate absorption: ↑MCV
  2. ↓ Fat absorption: Steatorrhea & deficiency of fat soluble vitamins
  3. ↓ Water absorption: Voluminous diarrhea.
  • Note: Terminal ileum is least affected in Celiac disease; so, vitamin B12 absorption is not affected.
  • The main presenting features are:
  1. Diarrhea
  2. Steatorrhea
  3. Dermatitis herpetiformis.

Dermatitis herpetiformis:

  • Blisters characteristically located at extensor surface of upper and lower limbs (elbow is a common site)
  • Intense pruritus is present.

 

Investigations:

  1. IgA anti-TTG (Anti-tissue transglutaminase): Most sensitive
  2. IgA anti-EMA (Anti-endomysial antibody): Most specific
  3. If asked “most sensitive & specific”/ “most preferred”, then answer anti-TTG
  4. IOC in case of selective IgA deficiency: IgG anti-deamidated gluten peptide.
  5. Gold standard: Biopsy.

 

Biopsy:

  • The hallmark of celiac disease is an abnormal small intestinal biopsy and the response of the condition (including symptoms and histologic changes) to the elimination of gluten from the diet.
  • Biopsy findings:
  1. ↑↑Intraepithelial CD8+ T-lymphocytes
  2. Villous atrophy
  3. Crypt hyperplasia
  4. Increased villous: crypt ratio (normal: 3-5:1).

  • Diagnosis of Dermatitis herpetiformis is based on direct immunofluorescence (DIF) of skin biopsy which shows dermal tip granular IgA deposits.

Rx:

  • Celiac disease: Gluten free diet
  • Dermatitis herpetiformis: Gluten free diet + Dapsone (because of its antineutrophilic property).

 

Celiac disease predisposes to the following malignancy:

  1. Plummer Vinson syndrome: SCC of pharynx & esophagus
  2. Adenocarcinoma of small intestine
  3. T cell lymphoma of small intestine (MC cause of death in Celiac disease).

 

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