Eosinophilic Gastroenteritis

Eosinophilic gastroenteritis is a rare disorder of eosinophilic infiltration of the gastric and small bowel wall (eosinophilic gastrointestinal disease affecting the stomach and small bowel) with gastrointestinal symptoms.

• Prevalence 1 to 30 per 100,000; peaks in 3rd to 5th decades; many have atopy (50%): asthma, eczema, food allergy, allergic rhinitis.
• Klein classification by depth: mucosal (most common; malabsorption, protein losing enteropathy, bleeding), muscular (obstruction), serosal (eosinophilic ascites).
• Pathogenesis: Th2 response (IL 4, IL 5, IL 13) with eotaxin 3, food and aeroallergens as triggers.
• Differential: parasites (Strongyloides, Ascaris, Anisakis), drugs (NSAIDs, gold), hypereosinophilic syndrome, EGPA, Crohn disease, lymphoma, mastocytosis.

• Mucosal: abdominal pain, nausea, vomiting, diarrhoea, weight loss, early satiety, protein losing enteropathy, iron deficiency, bleeding.
• Muscular: gastric outlet or small bowel obstruction, thickened wall.
• Serosal: ascites (exudative, eosinophilic), pleural effusion, abdominal distension.
• Peripheral eosinophilia in 50 to 80%.
• Relapsing remitting course.

Criteria: gastrointestinal symptoms, biopsy showing eosinophilic infiltration (over 20 to 30 eosinophils per high power field in the stomach, small intestine, or colon; or eosinophilic infiltration of the bowel wall), or eosinophilic ascites, and exclusion of other causes of eosinophilia.

• Full blood count, IgE, ESR, CRP, albumin, iron studies, stool for ova and parasites, Strongyloides serology, fungal serology.
• Upper endoscopy with multiple biopsies (gastric antrum, duodenum, and normal appearing mucosa); full thickness biopsy (laparoscopic) for muscular or serosal disease.
• CT/MR enterography: wall thickening, folds, obstruction, ascites.
• Ascitic fluid analysis (eosinophils over 50%).
• Allergy testing (skin prick, specific IgE), but limited reliability.
• Exclude hypereosinophilic syndrome (FIP1L1 PDGFRA, cardiac assessment) and EGPA (ANCA).

• Dietary: empirical elimination diet (six food elimination: milk, wheat, egg, soy, nuts, fish/shellfish) for 6 to 8 weeks, then reintroduction; elemental diet in refractory cases.
• Corticosteroids (most effective, response in 80 to 90%): prednisolone 20 to 40 mg daily (0.5 to 1 mg/kg) for 2 to 4 weeks, then taper over 2 to 3 months; the serosal and muscular forms respond fastest.
• Steroid sparing or topical therapy: budesonide 9 mg daily (open capsule or enteric coated), azathioprine 2 mg/kg, 6 mercaptopurine.
• Adjuncts: montelukast 10 mg daily, ketotifen 1 mg twice daily, sodium cromoglicate 100 to 200 mg four times daily (limited).
• Biologics: dupilumab 300 mg every 2 weeks (IL 4 receptor), mepolizumab 100 to 300 mg monthly, benralizumab 30 mg every 8 weeks, vedolizumab, omalizumab.
• Treat nutritional deficiencies, bleeding, and obstruction (surgery or endoscopic dilation if fibrotic).
• Antiparasitic therapy (ivermectin 200 micrograms/kg) before steroids in endemic areas.
• Relapse is common (up to 50%), so maintenance low dose steroids or budesonide. Monitor eosinophil counts and symptoms.