In Brief Objective: Determine whether size and other preoperative parameters predict malignant or invasive intraductal papillary mucinous neoplasia (IPMN). Summary Background Data: From 1991 to 2006, 150 patients underwent 156 operations for IPMN. Methods: Prospectively collected, retrospective review of a single academic institution's experience. All preoperative parameters including a detailed radiologic-based classification of IPMN type, location, distribution, size, number, cytology, and mural nodularity were correlated with IPMN pathology. Results: Malignant IPMN was present in 32% of cases, whereas 19% of cases were invasive. IPMN type and main pancreatic duct diameter were significant predictors of malignant IPMN (P < 0.001). Side-branch lesion number was negatively associated with invasive IPMN (P = 0.03). Side-branch size, location, and distribution did not predict IPMN pathology. The presence of mural nodules was associated with malignant and invasive IPMN (P < 0.001; P < 0.02). Atypical cytopathology was significantly associated with malignant and invasive IPMN (P < 0.001; P < 0.001). Multivariate analysis demonstrated mural nodularity and atypical cytopathology were predictive of malignancy and/or invasion in branch-type IPMN. Conclusions: To lower the rate of invasive pathology, surgery should be recommended for fit patients with main-duct IPMN and for branch-duct IPMN with mural nodularity or positive cytology irrespective of location, distribution, or size. Intraductal papillary mucinous neoplasia (IPMN) is an increasingly recognized condition, which can lead to pancreatic cancer. Previous studies have attempted to correlate IPMN size with the probability of malignant or invasive IPMN pathology. Based on our study, no correlation exists between side branch size and malignant or invasive IPMN pathology.

Intraductal Papillary Mucinous Neoplasms