AIM To investigate the reproducibility of the in vivo endoscopic ultrasound(EUS)-guided needle based confocal endomicroscopy(n CLE) image patterns in an ex vivo setting and compare these to surgical histopathology for characterizing pancreatic cystic lesions(PCLs). METHODS In a prospective study evaluating EUS-nC LE for evaluation of PCLs, 10 subjects underwent an in vivo nC LE(AQFlex nC LE miniprobe; Cellvizio, MaunaK ea, Paris, France) during EUS and ex vivo probe based CLE(pC LE) of the PCL(Gastroflex ultrahigh definition probe, Cellvizio) after surgical resection. Biopsies were obtained from ex vivo CLE-imaged areas for comparative histopathology. All subjects received intravenous fluorescein prior to EUS and pancreatic surgery for in vivo and ex vivo CLE imaging respectively. RESULTS A total of 10 subjects(mean age 53 ± 12 years; 5 female) with a mean PCL size of 34.8 ± 14.3 mm were enrolled. Surgical histopathology confirmed 2 intraductal papillary mucinous neoplasms(IPMNs), 3 mucinous cystic neoplasms(MCNs), 2 cystic neuroendocrine tumors(cystic-NETs), 1 serous cystadenoma(SCA), and 2 squamous lined PCLs. Characteristic in vivo nC LE image patterns included papillary projections for IPMNs, horizon-type epithelial bands for MCNs, nests and trabeculae of cells for cystic-NETs, and a “fern pattern” of vascularity for SCA. Identical image patterns were observed during ex vivo pC LE imaging of the surgically resected PCLs. Both in vivo and ex vivo CLE imaging findings correlated with surgical histopathology.CONCLUSION In vivo n CLE patterns are reproducible in ex vivo p CLE for all major neoplastic PCLs. These findings add further support the application of EUS-nC LE as an imaging biomarker in the diagnosis of PCLs. AIM To investigate the reproducibility of the in vivo endoscopic ultrasound(EUS)-guided needle based confocal endomicroscopy(n CLE) image patterns in an ex vivo setting and compare these to surgical histopathology for characterizing pancreatic cystic lesions(PCLs). METHODS In a prospective Study evaluating EUS-nC LE for evaluation of PCLs, 10 subjects underwent an in vivo nC LE(AQFlex nC LE miniprobe; Cellvizio, MaunaK ea, Paris, France) during EUS and ex vivo probe based CLE(pC LE) of the PCL ( Gastroflex ultrahigh definition probe, Cellvizio) after surgical resection. Biopsies were obtained from ex vivo CLE-imaged areas for comparative histopathology. All subjects received intravenous fluorescein prior to EUS and pancreatic surgery for in vivo and ex vivo CLE imaging respectively. RESULTS A total of 10 subjects(mean age 53 ± 12 years; 5 female) with a mean PCL size of 34.8 ± 14.3 mm were enrolled. Surgical histopathology confirmed 2 intraductal papillary mucinous neoplasms(IPMNs), 3 Mucinous cystic neoplasms (MCNs), 2 cystic neuroendocrine tumors (cystic-NETs), 1 serous cystadenoma (SCA), and 2 squamous lined PCLs. Characteristic in vivo nC LE image patterns included papillary projections for IPMNs, horizon-type epithelial bands for MCNs , nests and trabeculae of cells for cystic-NETs, ​​and a “fern pattern” of vascularity for SCA. Identical image patterns were observed during ex vivo pC LE imaging of the surgically resected PCLs. Both in vivo and ex vivo CLE imaging findings. Related with surgical histopathology.CONCLUSION In vivo n CLE patterns are reproducible in ex vivo p CLE for all major neoplastic PCLs. These findings add further support the application of EUS-nC LE as an imaging biomarker in the diagnosis of PCLs.