Uncinate Duct Dilation in Intraductal Papillary Mucinous Neoplasms of the Pancreas: A Radiographic Finding with Potentially Increased Malignant Potential

Risk of high-grade dysplasia and invasive carcinoma in intraductal papillary mucinous neoplasms (IPMN) of the pancreas is increased in main duct compared to branch duct lesions. We hypothesized that isolated uncinate duct dilation may also be a radiographic indicator of high-risk disease, as the primary drainage of this portion of the gland originates from a distinct embryologic precursor. All patients with available preoperative imaging who underwent resection for IPMN between 1994 and 2010 were included (n = 184). Imaging studies were reviewed by an experienced radiologist who was blinded to the pathologic results, and studies were categorized as main duct, branch duct, or combined-duct. The presence of uncinate duct dilation was assessed as a risk factor for tumors which proved to have high-grade dysplasia (HGD) or invasive carcinoma (IC) on pathologic assessment. IPMN with HGD or IC were identified in 82 of 184 cases (45 %). Without considering uncinate duct dilation, IPMN with HGD or IC were present in 84 % of patients with main duct IPMN (n = 31/37), 58 % with combined-duct IPMN (n = 23/40), and 26 % with branch \duct IPMN (n = 28/107). Dilation of the uncinate duct was observed in 47 patients, with or without main duct dilation, and 30 of these (64 %) contained HGD or IC on pathology. Isolated uncinate duct dilation without main duct dilation was observed in 17 patients, and 11 (65 %) had HGD. On multivariate analysis of IPMN without associated main duct dilation, uncinate duct dilation was independently associated with IPMN with HGD or IC (p = 0.002). Uncinate duct dilation on preoperative radiologic imaging appears to be an additional risk factor for IPMN-associated high-grade dysplasia or adenocarcinoma.