Discrepancy Between Forceps Biopsy and Resection in Colorectal Polyps: A 1686 Paired Screening-Therapeutic Colonoscopic Finding

PURPOSE: To identify pathology discrepancy between forceps biopsies and polypectomy specimens in colorectal polyps, as well as the reliability of biopsy-based treatment strategy. METHODS: All endoscopic polypectomy cases with forceps biopsies performed within 6 months were included in the study. The biopsies were compared with polypectomy specimens in terms of concordance of histological diagnosis. A logistic regression model was used to investigate the independent predictors of upgrade in histological diagnosis compared with concordance in histological diagnosis. RESULTS: A total of 1686 paired screening-therapeutic colonoscopies and 1739 paired biopsy-polypectomy specimens were enrolled in the study. The grade of dysplasia in 84.5% of biopsy specimens were concordant to polypectomy specimens, but this proportion decreased to 75.4% when the specimens were classified using tubular or villousness structure. 10.1% and 5.4% of biopsy specimens were upgraded and downgraded in assessing grade of dysplasia, respectively, while 14.3% and 10.3% of biopsy specimens were upgraded and downgraded in assessing tubular or villousness structure, respectively. In subgroup analysis stratified by size of polyps, 9.0% and 10.6% of biopsies obtained from polyps smaller than 10 mm were upgraded in assessing dysplasia and tubular or villousness structure, respectively. This proportion increased to 10.7% and 21.3%, respectively, in biopsies obtained from polyps larger than 10 mm. Larger size of polyps and pedunculated polyps were associated with a higher incidence of upgrade in histological diagnosis. Nearly 25% of biopsy specimens with high-grade dysplasia were identified as adenocarcinoma in polypectomy specimens. CONCLUSION: The concordance between biopsy and polypectomy specimens is not adequate. The biopsy-based treatment strategy is not reliable and should not be considered as an indicator for further treatment, particularly in large or pedunculated polyps.