The interobserver agreement of optical features used to differentiate benign from neoplastic biliary lesions assessed at balloon-assisted cholangioscopy

Background and Aim Balloon-assisted cholangioscopy allows mucosal assessment of the biliary tree with pediatric endoscopes. No validated optical criteria exist to differentiate benign from neoplastic biliary lesions. We aimed to identify, validate, and revalidate optical features differentiating benign from neoplastic biliary lesions. Furthermore, we aimed to determine whether cholangioscopic appearance allows endoscopists to accurately differentiate benign from neoplastic biliary lesions. Methods Baseline: from 44 de-identified balloon-assisted cholangioscopy videos, a blinded investigator analyzed potential optical features distinguishing benign from neoplastic biliary lesions. Validation: during the initial teaching phase, 20 endoscopists viewed video clips of 11 optical features identified in the baseline study. At the subsequent test phase, 20 further video clips were assessed by the endoscopists blinded to clinical details and questionnaires completed for the presence or absence of optical features, favored diagnosis and diagnostic confidence. Revalidation: The six identified optical features from the validation study with at least moderate agreement were revalidated the same way 12 months later assessing 20 new lesions. Results Baseline: 11 optical features were found to differentiate benign from neoplastic biliary lesions. Validation and revalidation: six optical features demonstrated at least moderate interobserver agreement (irregular margin, dark mucosa, adherent mucous, papillary projections, tubular, or branched/disorganized surface structures). Endoscopists correctly diagnosed lesions as benign in 89% and neoplastic in 83%. When highly confident, endoscopists correctly diagnosed 96% of benign and 87% neoplastic lesions. Conclusions Six features were validated and revalidated to differentiate benign from neoplastic biliary lesions. When highly confident with a diagnosis, endoscopists usually differentiate benign from neoplastic biliary lesions.