Assessment of peri-polyp biopsy specimens of flat mucosa in patients with inflammatory bowel disease

Background and Aims: When colon polyps are removed in the setting of inflammatory bowel disease (IBD) involving the large intestine, biopsy sampling of the flat mucosa surrounding such polyps have been recommended, but there are no data to support this practice. Methods: We reviewed endoscopic and pathologic findings in IBD patients who had dysplastic polyps removed and biopsy sampling of the adjacent flat mucosa. We assessed risk for subsequent neoplasia based on the presence or absence of dysplasia in the peri-polyp flat mucosa and based on number and grade of index polypoid lesions. Kaplan-Meier survival analysis was performed. Results: Fifty-six IBD patients (68% ulcerative colitis [UC]) underwent 102 colonoscopies, in which 129 dysplastic polyps were resected. Five hundred three biopsy procedures of the surrounding flat mucosa were performed (mean, 3.9 biopsy samples per polyp), of which 16 (3.2%) were dysplastic. Thirty-four patients (21 UC) had follow-up in a median of 1.7 years (range,.02-15) and 147 colonoscopies. The presence of dysplasia in peri-polyp biopsy specimens during index colonoscopy was not associated with risk of developing high-grade dysplasia (HGD) or cancer (Pearson χ² test =.19). The size and number of dysplastic polyps were not predictive of neoplastic outcomes, but the probability of developing subsequent advanced neoplasia for polypoid low-grade dysplasia was 18%, 29%, and 40% by 1, 3, and 5 years, respectively, and for polypoid HGD was 50%, 60%, and 70% by 1, 3, and 5 years, respectively (hazard ratio, 7.0; standard error, 4.8). Conclusions: In patients with IBD-associated colitis, biopsy sampling of the mucosa adjacent to discrete dysplastic polypoid lesions are low yield and do not predict findings in follow-up examinations. However, the grade of dysplasia of the polyp itself is predictive of subsequent advanced neoplasia.