Introduction: Prior studies have validated EUS-guided needle-based confocal laser endomicroscopy (nCLE) diagnosis of IPMNs by detection of characteristic “papillae”. We sought to further assess the performance and interobserver agreement (IOA) of EUS-nCLE for differentiating IPMNs with high grade dysplasia (HGD) or adenocarcinoma (HGD-Ca) from those with low or intermediate-grade dysplasia (LGD).
Methods: In a prospective single center study evaluating EUS-nCLE for the evaluation of pancreatic cysts, 26 patients with a definitive diagnosis of IPMNs (surgery=24; confirmatory cytology/metastatic adenocarcinoma=2) were identified. EUS-nCLE imaging variables predictive (Table 1) of advanced neoplasia were internally derived amongst 3 EUS-MDs with experience in nCLE (Fig. 1).
Six external endosonographers (nCLE experience>30 cases) blinded to all clinical data, reviewed all nCLE videos (Fig. 2). After 2 weeks, the assessors reviewed the same images in a different sequence. A self-study tutorial of nCLE variables predictive of HGD-Ca was provided before each review. Prior to the second review, an interactive web-based discussion was also conducted. The IOAs (κ statistic) of diagnostic nCLE image patterns to detect HGD-Ca were calculated.
Results: Among the subjects with IPMNs (16 mixed, 10 branch-duct; mean size 3.4±1.7 cm), there were 9 with LGD and 17 with advanced neoplasia (12 HGD, 2 non-invasive and 3 invasive adenocarcinoma). The six observers identified papillary structures diagnostic of IPMN in all videos. The overall sensitivity, specificity, accuracy, and IOA of EUS-nCLE to diagnose HGD-Ca was 90%, 73%, 84%, and κ=0.54 (moderate), respectively (Table 1).
Correlating with histopathological progression of dysplasia in IPMNs, nCLE imaging characteristics of papillary “thickness” (indicative of cellular and nuclear stratification) and “darkness” (increased nuclear/cytoplasmic ratio) were the most sensitive (90% and 91%) and accurate (86% and 84%) with substantial (κ=0.61) and moderate (κ=0.55) IOAs for detecting HGD-Ca, respectively (Table 1).
Discussion: In this derivation study, blinded expert endosonographers identified several EUS-nCLE imaging features of IPMNs that are associated with advanced neoplasia. Further studies are needed to refine and validate these features for applying EUS-nCLE to identify advanced dysplasia.
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