Pyloric gland metaplasia: Potential histologic predictor of severe pouch disease including Crohn's disease of the pouch in ulcerative colitis.

Crohn's disease of the pouch (CDP) is seen in a subset of ulcerative colitis (UC) patients following ileal pouch-anal anastomosis (IPAA). Histologic or clinical predictors of CDP are unknown. UC patients with subsequent CDP diagnosis were identified. The rationales for the diagnosis, the interval from the initial signs of CDP to the diagnosis, family history and smoking history were reviewed. Archived pathology materials were reviewed for the presence of pyloric gland metaplasia (PGM) and compared with those from UC with similar severity of pouchitis with CDP (matched UC controls), random UC controls, and ileocolectomies from primary CD patients. CDP diagnosis was made in 26 (18.1%) of 144 patients; all of them met commonly used diagnostic criteria for CDP. The diagnosis was rendered on average 15 months after the initial CD-like signs. PGM was found in 58% of CDP, more common than random UC controls but no different from primary CD and matched UC controls. PGM preceded first signs of CD in a subset. Patients with a family history of CD were more likely to develop CDP than those without a family history of any type of inflammatory bowel disease. Smoking status did not affect the likelihood of developing CDP. Finding PGM in proctocolectomy, ileostomy and follow-up biopsies in UC patients post IPAA may warrant close follow up for the potential development of pouchitis. Some of these patients, especially those with family history of CD, may further progress and develop severe disease meeting the clinical diagnostic criteria for CDP.