Predictors for underestimated pathology in forceps biopsy compared with resection specimen of colorectal neoplasia; focus on surface appearance.

BACKGROUND: There have been substantial differences in pathologic results between forceps biopsies (FB) and resection specimen (RS) of the colorectal neoplasm. The aim of this study was to investigate predictive factors of the underestimated pathology in FB compared with RS. METHODS: Data from 248 consecutive patients with colorectal intraepithelial neoplasm ≥10 mm, which was removed by endoscopic mucosal resection or endoscopic submucosal dissection, were reviewed retrospectively. We excluded patients with no FB on the neoplasm before the resection. Demographic data and tumor characteristics including size, locations, surface appearances, and the number of FB fragments were evaluated as potential factors associated with the discrepancies by logistic regression analysis. RESULTS: Overall, 179 lesions from 171 patients were included in the study (size, 28.37 ± 12.00 mm; range 10-80 mm). The overall number of discrepancy cases was 103 (57.5%), where 90 (50.3%) were underestimated in FB and 13 (7.2%) downgraded in their RS. In the multivariate analysis, round [odds ratio (OR) 4.46, 95% confidence interval (CI) 1.76-11.30, p = 0.002], depressed (OR 3.23, 95% CI 1.11-9.39, p = 0.031), and mixed type of surface appearance (OR 5.47, 95% CI 2.38-12.60, p < 0.001), and tumor size ≥30 mm (OR 2.14, 95% CI 1.12-4.10, p = 0.021) were significant predictive factors for underestimated pathology in FB. CONCLUSIONS: Underestimation in FB is remarkable in colorectal tumors ≥10 mm in size. This discrepancy is associated with the tumor characteristics, such as surface appearance and size. Endoscopic characteristics of tumor should be carefully examined for an adequate management strategy of colorectal epithelial neoplasm.