Purpose: 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.
Methods: 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 ≥10 mm.
Results: 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.
Conclusions: 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.