Retrospective Application of 2012 Revised International Consensus Guidelines to Suspected Mucinous-Type Pancreatic Cysts Managed in the Sendai Era

1.1.Background:Pancreatic cystic lesions (PCL) are a common clinical problem. International consensus guidelines were published in 2006 and revised in 2012 to assist clinicians in the diagnosis and management. 1.2.Methods:2012 international consensus guidelines (ICG-2012) were retrospectively applied to PCLs originally managed with ICG-2006. PCLs diagnosed in 2008-2012 (Sendai era) were included if: (1) lesions were suspected to be BD-IPMN (branch duct intraductal papillary mucinous neoplasm) prior to surgery with carcinoembryonic antigen < 192, (2) required resection based on ICG-2006, (3) final diagnosis verified by histopathology. Performance of ICG-2012 was tested with indications for resection defined as carcinoma and pre-malignant lesions such as pancreatic intraepithelial neoplasia (PanIN). 1.3.Results:15 PCLs met the inclusion criteria. Applying ICG-2012, following were the sensitivity, specificity, negative predictive value, positive predictive value, and accuracy, expressed as % (N/C = not calculable), for each of the criteria featured in the proposed algorithm. High-risk stigmata: enhancing solid component within cyst (50, 92, 92, 50, 87), main pancreatic duct (MPD) ≥ 10mm (0, 100, 87, N/C, 87). Clinical worrisome features: pancreatitis (0, 85, 85, 0, 73). Worrisome features on cross sectional imaging: cyst ≥ 3cm (0, 38, 71, 0, 33), thickened/enhancing cyst walls (0, 85, 85, 0, 73), MPD 5-9 mm (33, 100, 87, 100, 88), non-enhancing mural nodule (0, 92, 86, 0, 80), abrupt change in PD caliber with distal atrophy (100, 100, 100, 100, 100). EUS (endoscopic ultrasound) features: definite mural nodule (100, 62, 100, 29, 67), MPD suspicious for involvement (0, 100, 87, N/C, 87), cytology (0, 100, 92, N/C, 92). Channeling PCLs through the ICG-2012 algorithm, 4 lesions [1 adenocarcinoma and 3 MCNs (if the resection indication was expanded to include MCNs)] that met resection criteria with ICG-2006 would not be resected utilizing ICG-2012. Conclusion:Feature in ICG-2012 algorithm that predicted carcinoma/pre-malignant lesions with highest accuracy was abrupt change in PD caliber with distal atrophy on cross sectional imaging. Cyst details such as mural nodules may be missed on cross sectional imaging but detected on EUS, which suggests a possible need for at least one EUS in PCL size of 1-2 cm