Inflammatory and Immunologic Disorders of the Gut
Scope
Covers Crohn disease, ulcerative colitis, food protein-induced allergic proctocolitis (FPIAP), eosinophilic gastroenteritis, and immunodeficiency-associated enteropathy.
Concepts
- IBD phenotypes: Crohn is transmural, skip lesions, perianal disease, granulomas; ulcerative colitis is mucosal, continuous from rectum, with bloody diarrhea.
- Diagnosis: endoscopy with biopsies; exclude infection; check inflammatory markers and growth.
- FPIAP: blood-streaked stools in a well-appearing infant; resolves with maternal elimination of cow's milk protein.
- Eosinophilic gastroenteritis: peripheral eosinophilia, protein-losing enteropathy, responds to steroids or elimination.
- Immunodeficiency: recurrent infections, failure to thrive, chronic diarrhea; evaluate immune function.
Traps
Questions conflate FPIAP with necrotizing enterocolitis or infection-FPIAP occurs in thriving infants. Another trap: assuming IBD requires elevated CRP or ESR; they can be normal. Beware missing perianal Crohn disease in a child with fistulas.
Worked example
A 3-month-old, breastfed, thriving, with streaks of blood in stool: FPIAP. Maternal cow's milk elimination usually resolves symptoms; no endoscopy needed.
Rule of thumb
Bloody diarrhea in a thriving infant = FPIAP; in a sick child = infection or surgical cause. IBD can have normal inflammatory markers.