Clinicopathologic analysis of surgically proven intraductal papillary mucinous neoplasms of the pancreas in SNUH: a 15-year experience at a single academic institution

The clinical importance of intraductal papillary mucinous neoplasm of the pancreas (IPMN) has been increasing with a large number of newly diagnosed IPMN. This study was designed to explore the characteristics of resected IPMN and to determine the predictive factors for malignant and invasive IPMN. Retrospective review of a prospectively collected database was performed on 187 consecutive patients following IPMN surgery between 1994 and 2008 at a tertiary institute. The main duct type IPMN was radiologically defined as main pancreatic duct dilation > 5 mm rather than previously defined a parts per thousand yen10 mm. The morphologic types of IPMN included 28 main duct (IPMN-M, 15.0%), 118 branch duct (IPMN-Br, 63.1%), and 41 mixed (IPMN-Mixed, 21.9%) IPMNs. There were 23 patients with adenoma, 106 borderline atypia, 15 carcinoma in situ, and 43 invasive carcinoma. Sixty-nine extrapancreatic malignancies were diagnosed in 61 (32.6%) patients. Based on multivariate analysis, IPMN-M was statistically significant predictor of malignancy/invasiveness (p = 0.013/p = 0.028). In patients with IPMN-Br, the presence of mural nodule was a predictive factor for malignancy/invasiveness (p = 0.005/p = 0.002). In patients with IPMN-Mixed, mural nodule (p = 0.038/p = 0.047) and wall thickening (> 2 mm, p = 0.015/p = 0.046) were risk factor for malignancy/invasiveness and elevated CA19-9 (p = 0.046) for invasiveness. The main pancreatic duct diameter (> 5 mm) is a significant predictor for malignancy and invasiveness. Therefore, IPMN patients with main pancreatic duct dilatation (> 5 mm) should be considered surgical resection. Mural nodule is the indicator of surgery in IPMN-Br and IPMN-Mixed. In case of IPMN-Mixed with wall thickening or elevated serum CA19-9, surgical resection is recommended.