Predictors of malignancy in main duct intraductal papillary mucinous neoplasm of the pancreas.

Abstract Background and aims The international consensus guidelines updated in 2017 recommended surgery to all main duct intraductal papillary mucinous neoplasms (MD-IPMNs) with the main pancreatic duct (MPD) of 10 mm or more and those with mural nodule regardless of its size. The aim of the present study is to identify predictors of malignancy in MD-IPMN among preoperative factors including sizes of MPD and mural nodule. Methods Twenty-six benign MD-IPMNs (7 resected and 19 nonresected MD-IPMNs) and 32 malignant MD-IPMNs (31 resected and 1 nonresected MD-IPMN) were enrolled. Magnetic resonance cholangiopancreatography (MRCP), computed tomography (CT), endoscopic ultrasonography (EUS), and cytology was performed using pancreatic juice collected by endoscopic retrograde pancrestography (ERP). Resected IPMNs were classified as benign or malignant by histological examination; nonresected MD-IPMNs by imaging, cytology, and observation. Cutoff values of candidate parameters were determined by receiver operating characteristic (ROC) curves. Univariate and multivariate analyses by regression model were performed. Results Sizes of MPD and mural nodule and result of cytology differed significantly between benign and malignant groups. Cutoff values of MPD and mural nodule sizes were 15 mm and 10 mm with areas under the curve (AUC) of 0.66 and 0.86, respectively. Mural nodule of 10 mm or more (OR, 8.32; 95% CI, 1.13-61.2; P=0.038) and positive cytology (OR, 42.5; 95% CI, 4.10-439; P=0.002) were shown to be independent predictors of malignancy by multivariate analysis. When MD-IPMNs that had either of the predictors were diagnosed to be malignant, sensitivities, specificities, and overall accuracy for malignancy were 94%, 85%, and 90%, respectively. Conclusions Mural nodule of 10 mm or more and positive cytology were independent predictors of malignancy in MD-IPMN.