Published online Nov 16, 2021. doi: 10.4253/wjge.v13.i11.555
Peer-review started: February 23, 2021
First decision: June 17, 2021
Revised: June 25, 2021
Accepted: September 6, 2021
Article in press: September 6, 2021
Published online: November 16, 2021
Processing time: 259 Days and 8.1 Hours
Some pancreatic cystic lesions (PCLs) have unequivocal malignant potential, but the precise determination of the risk of progression with endoscopic ultrasound (EUS), fine-needle aspiration (FNA), analysis of carcinoembryonic antigen (CEA) level, and cytology is still challenging. Among the novel tools for assessing PCLs, needle-based confocal endomicroscopy (nCLE) has been identified as one of the most sensitive, but some concerns have been raised about its safety and reproducibility.
The first clinical trials published described a correlation between nCLE and histological features, and established the criteria for characterizing the most frequent type of cysts. However, no multicenter prospective studies have been performed at the time of study conception to evaluate the safety of the procedure and interobserver agreement (IOA).
The purpose of this multicenter prospective study was to evaluate the diagnostic accuracy of EUS-guided nCLE to differentiate mucinous from non-mucinous in PCLs compared to standard of care, by analysis of intracystic CEA and amylase level and/or cytology vs surgical pathology.
The strength of the study is its observational design in high-volume centers compared to the single-center studies previously published. All nCLE videos were independently reviewed by 6 observers blind to clinical or imaging information; each investigator provided a final diagnosis, and if the disagreement between reviewers was > 20%, videos were discussed together in order to reach a final nCLE consensus diagnosis. In the event of persistent disagreement among investigators, the videos were considered false negatives.
A total of 59 patients were enrolled in this study to receive EUS-FNA and nCLE. The procedure was technically feasible in 95% of patients; nCLE sensitivity, specificity, and accuracy for the diagnosis of mucinous lesions were 80% [95% confidence interval (CI): 65-90], 100% (95%CI: 72-100), and 84% (95%CI: 72-92), respectively, and for distinguishing mucinous from non-mucinous lesions compared to intracystic CEA > 192 ng/mL were 58% (95%CI: 43-72), 100% (95%CI: 73-100), and 67% (95%CI: 53-78), respectively. IOA for nCLE diagnosis was 0.76, and 10% of adverse events were recorded.
Our study confirmed the feasibility of nCLE and its excellent performance in the discrimination of mucinous vs non-mucinous lesions. This new finding confirms the possibility of an accurate pre-operative diagnosis. The strength of the study was the multicenter, prospective observational design and the selection of a study group of real undetermined pancreatic cysts without pancreatic duct communication and free of worrisome features; this was also a weakness due to the low number of cases with surgical/histological diagnosis. The excellent performance of nCLE opens various possible scenarios for the management of undetermined PCLs.
Future research should include fine-needle biopsies with biopsy forceps to improve pathological diagnosis without surgery.