Intraductal papillary mucinous neoplasms: predictors of malignant and invasive pathology.

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.