Prediction of malignancy in main duct or mixed‐type intraductal papillary mucinous neoplasms of the pancreas

Background/Purpose Surgical indications of main duct‐involved intraductal papillary mucinous neoplasm (IPMN), especially for main pancreatic duct (MPD) of 5‐9 mm, remain controversial. We aimed to predict malignancy risk of main duct‐involved IPMN. Methods Total 258 patients with main duct‐involved IPMN between 2000 and 2017 in our institute were retrospectively analyzed. Main duct IPMN was classified into segmental and diffuse‐type by dilated MPD pattern. Clinicopathologic features and predictive factors for malignancy were analyzed. Results Among 258 patients, 47 and 211 had pure main duct (segmental: 27, diffuse type: 20) and mixed type, respectively. Malignant IPMN presented higher in main duct type (66.0%) compared to mixed type (46.9%). The diffuse type (72.2%) had more invasive carcinoma than the segmental type (40.7%). Invasive IPMN risk increased proportionally to the MPD diameter (5 ≤ MPD