Risk factors for malignancy in branched-type intraductal papillary mucinous neoplasms of the pancreas during the follow-up period.

Abstract

The international consensus guidelines for the management of intraductal papillary mucinous neoplasm (IPMN) of the pancreas were revised in 2012 Tanaka (Pancreatology 12(3):183-197, 2012), making the indications for operation less aggressive. Therefore, the number of branch duct-type IPMN (BD-IPMN) patients requiring follow-up care is expected to increase in the future. The aim of this study was to identify risk factors for malignancy in BD-IPMN patients during the follow-up period. This study included 47 BD-IPMN patients without a mural nodule (MN) at the time of initial diagnosis and who subsequently underwent resection after a follow-up period of more than 3 months. Data for the patients were reviewed retrospectively, and the clinicopathological factors were investigated. In a univariate analysis, age (≧ 65 years), an increase in the main pancreatic duct (MPD) diameter, the MPD diameter at resection (≧ 5 mm), and the occurrence of MN were significantly associated with malignancy. The occurrence of MN was the only significant factor in a multivariate analysis. In addition, 7 of the 17 patients (41.2 %) who only exhibited an increase in the cyst diameter during the follow-up period were diagnosed as having malignancies. All 6 patients who exhibited an increase in the cyst diameter of 100 % or more were diagnosed as having carcinoma. During the follow-up period, the incidence of malignancy was higher among patients with BD-IPMNs and the occurrence of MN, an increase in the MPD diameter, or an increase ratio of 100 % or more in cyst diameter than the others; resection was recommended for these patients.