Development and Potential Utility of a New Scoring Formula for Prediction of Malignant Intraductal Papillary Mucinous Neoplasm of the Pancreas

Objective: A simple systemis needed to determinewhether surgery is indicated in cases of intraductal papillary mucinous neoplasm (IPMN). Methods: We conducted a retrospective study to identify factors predictive of malignant IPMN and thus simplify the treatment decision-making process. Ninety-six consecutive patients treated surgically for IPMN at Kyorin University Hospital (Tokyo, Japan) between 1994 and 2014 were included. Univariate and multivariate analyses were used to identify preoperative factors predictive of malignancy. A simple scoring formula was derived from the regression equation. Results: Twenty-two (23%) of the IPMNs were malignant, and 74 (77%) were benign. Pancreatic head tumor, cyst diameter of 47 mm or greater, and mural nodule diameter of 9 mm or greater were identified as significant predictors of malignant IPMN. The following scoring formula was developed: 4 x tumor location (pancreatic head, 1; pancreatic body or tail, 0) + 3 x cyst diameter (>= 47mm, 1; < 47 mm, 0) + 6 x mural nodule diameter (>= 9 mm, 1; < 9 mm, 0); the area under the receiver operating characteristic curve was 0.970. At a cutoff of 8 points, the diagnostic accuracy was excellent (sensitivity, 90.9%; specificity, 95.9%; accuracy, 94.8%). Conclusions: Our scoring systemhas potential as a simple screening tool for the identification of malignant IPMN.