[651] Atypical Histopathologic Features in Total Colectomy Specimens from Patients with Followup Proven Ulcerative Colitis

E Himmelfarb, O Chan, D Phan, D Dhall, P Fleshner, G Melmed, HL Wang. Cedars-Sinai Medical Center, Los Angeles, CA

Background: Strict application of the classic histopathologic assessment criteria for ulcerative colitis (UC) leaves many patients in the category of indeterminate or unclassifiable colitis even after total colectomy. About 5-10% of patients undergoing ileal pouch-anal anastomosis (IPAA) for UC develop Crohn Disease (CD) after IPAA. In this study, extensive clinical followup data was used to limit this bias by restricting assessments of colectomies to those patients who remained CD-free in the followup period.
Design: A total of 147 patients with initial diagnoses of UC or unclassifiable/indeterminate colitis who underwent total colectomy and completed at least 3 months of postoperative clinical followup were selected for the study. A list of histopathologic features atypical for UC was developed by literature study and discussion among a colorectal surgeon, a gastroenterologist and gastrointestinal pathologists specialized in inflammatory bowel disease. Detailed histopathologic reassessment of the colectomy specimens was carried out by two pathologists who were blinded to long-term patient outcomes. All patients who developed CD after colectomy were excluded from the analysis.
Results: The clinical followup time after total colectomy ranged from 3 to 144 months (mean: 37 months). During followup, 14 patients developed clinical CD and were excluded from the study. In the remaining 133 patients who remained CD-free, the following atypical histopathologic features were identified (n; %): discontinuous chronic changes in crypts (15; 11%), discontinuous active inflammation (36; 27%), focal transmural inflammation away from deeply ulcerated area (6; 5%), slit-like fissure (26; 20%), V-shaped ulcer (39; 29%), crypt granuloma (32; 24%), neural hypertrophy (7; 5%), muscle hypertrophy (5; 4%), discontinuous ileitis (8; 6%), ileal villous architectural distortion (10; 8%), and ileal ulcer (4; 3%). No true granuloma was identified in any of the cases.
Conclusions: Atypical histopathologic features are frequently found in colectomy specimens even in patients who remain CD-free during followup. Identification of these features should not be used to exclude a diagnosis of UC. Interaction between clinicians and pathologists proves helpful in resolving the diagnostic conundrum of colonic inflammatory bowel disease.
Category: Gastrointestinal

Wednesday, March 24, 2010 9:30 AM

Poster Session V # 60, Wednesday Morning


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