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Background and Aims: Interobserver agreement (IOA) among pancreaticobiliary (PB) pathologists in evaluating high-grade dysplasia and/or invasive carcinoma (HGD-IC) of IPMNs remains understudied. EUS-guided needle-based confocal endomicroscopy (nCLE) can evaluate papillary architecture in branch-duct (BD)-IPMNs. We assessed IOA among PB pathologists in classifying dysplasia in resected IPMNs and compared the performance of the Kyoto guidelines' high-risk stigmata (HRS) and pre-surgical EUS-nCLE against reclassified pathology., Methods: Subjects in prospective clinical trials (2015-2023) with resected IPMNs were included. Blinded PB-pathologists independently reviewed histopathology, achieving a consensus diagnosis. The accuracy of cyst fluid next-generation sequencing (NGS) analysis, EUS-nCLE, and Kyoto-HRS in predicting HGD-IC was compared with the reclassified pathology., Results: Among 64 subjects, 25 (39%) exhibited HGD-IC (17 HGD, 8 IC). Disagreements occurred in 14% of cases with substantial IOA (kappa=0.70; 95%CI: 0.53-0.88) between two PB-pathologists for differentiating HGD-IC vs. low-grade dysplasia. To detect HGD-IC, the sensitivity, specificity, and accuracy of Kyoto-HRS and EUS-nCLE were 52%, 95%, 78%, and 68%, 87%, 80%, respectively. Integrating nCLE with Kyoto-HRS improved sensitivity to 80%, with specificity and accuracy at 82% and 81%, respectively. The sensitivity, specificity, and accuracy of NGS (n=47) to detect HGD-IC was 6.3%, 100%, and 68%, respectively. A unique subset of IPMNs were identified in all (n=8, p=0.01) cases where pre-surgical EUS-nCLE underestimated dysplasia revealing a distinct micropapillary architecture on post-surgical histopathology., Conclusions: Despite substantial IOA among experienced PB-pathologists, a second pathologist's review may be warranted for dysplasia classification in IPMNs under certain circumstances. Incorporating an imaging biomarker such as EUS-nCLE with Kyoto-HRS improves sensitivity for HGD-IC without sacrificing accuracy., (Copyright © 2024 American Society for Gastrointestinal Endoscopy. Published by Elsevier Inc. All rights reserved.)

Background and Aims: EUS-guided needle-based confocal laser endomicroscopy (nCLE) characteristics of common types of pancreatic cystic lesions (PCLs) have been identified; however, surgical histopathology was available in a minority of cases. We sought to assess the performance characteristics of EUS nCLE for differentiating mucinous from non-mucinous PCLs in a larger series of patients with a definitive diagnosis., Methods: Six endosonographers (nCLE experience >30 cases each) blinded to all clinical data, reviewed nCLE images of PCLs from 29 patients with surgical (n = 23) or clinical (n = 6) correlation. After 2 weeks, the assessors reviewed the same images in a different sequence. A tutorial on available and novel nCLE image patterns was provided before each review. The performance characteristics of nCLE and the κ statistic for interobserver agreement (IOA, 95% confidence interval [CI]), and intraobserver reliability (IOR, mean ± standard deviation [SD]) for identification of nCLE image patterns were calculated. Landis and Koch interpretation of κ values was used., Results: A total of 29 (16 mucinous PCLs, 13 non-mucinous PCLs) nCLE patient videos were reviewed. The overall sensitivity, specificity, and accuracy for the diagnosis of mucinous PCLs were 95%, 94%, and 95%, respectively. The IOA and IOR (mean ± SD) were κ = 0.81 (almost perfect); 95% CI, 0.71-0.90; and κ = 0.86 ± 0.11 (almost perfect), respectively. The overall specificity, sensitivity, and accuracy for the diagnosis of serous cystadenomas (SCAs) were 99%, 98%, and 98%, respectively. The IOA and IOR (mean ± SD) for recognizing the characteristic image pattern of SCA were κ = 0.83 (almost perfect); 95% CI, 0.73-0.92; and κ = 0.85 ± 0.11 (almost perfect), respectively., Conclusions: EUS-guided nCLE can provide virtual histology of PCLs with a high degree of accuracy and inter- and intraobserver agreement in differentiating mucinous versus non-mucinous PCLs. These preliminary results support larger multicenter studies to evaluate EUS nCLE. (Clinical trial registration number: NCT02516488.)., (Copyright © 2017 American Society for Gastrointestinal Endoscopy. Published by Elsevier Inc. All rights reserved.)