3D volumetric pathology of colorectal polyps identifies additional high-risk features and modifies endoscopic surveillance category assignment

Background Conventional two-dimensional (2D) pathology samples less than 0.1% of colorectal polyp tissue and may miss clinically relevant histologic features. Here, we compared three-dimensional (3D) volumetric pathology with standard 2D evaluation to determine whether expanded sampling identifies additional high-risk features and alters endoscopic surveillance recommendations. Methods In this prospective single-center study, 158 colorectal polyps from 100 patients (143 adenomas ≥ 6 mm and 15 hyperplastic polyps with endoscopically discordant impressions) underwent three independent evaluations – the original 2D pathology report, an independent 2D digital review by three blinded pathologists, and 3D volumetric fluorescence imaging on 150-µm sections. Surveillance intervals followed United States Multi-Society Task Force 2020 guidelines. Interobserver agreement was assessed by Fleiss’ κ, whereas surveillance reclassification was tested with the McNemar exact test. Results 3D pathology identified histologic discrepancies in 35.0% of adenomas (50/143), with 34.8% (40/115) of tubular adenomas reclassified as tubulovillous adenomas and 5.8% (8/139) of low-grade dysplasia cases upgraded to high-grade dysplasia. Among the 15 endoscopically discordant hyperplastic polyps, 6 (40.0%) were reclassified as adenomatous lesions. Overall, 32 of 100 patients (32%) were reassigned to higher-risk surveillance categories – with the high-risk group rising from 25 to 56 (paired odds ratio = 32.0; P < .001). Fleiss’ κ was 0.696 for 2D and 0.726 for 3D analysis. Conclusions 3D volumetric pathology detected villous architecture and high-grade dysplasia overlooked on standard 2D sections, reclassifying one-third of patients into higher-risk surveillance groups. Prospective studies are warranted to determine whether 3D-based risk stratification may reduce post-colonoscopy colorectal cancer. Trial registration Taipei Medical University Hospital Joint Institutional Review Board, reference N202310020. Issued on 14 December 2023.