['The management of branch duct-type intraductal papillary mucinous neoplasms (IPMNs) remains controversial. This study aimed to elucidate the preoperative clinical factors that identify high-risk malignant transformation in branch duct-type IPMN.', 'We retrospectively evaluated 38 patients diagnosed with branch duct-type IPMN who underwent pancreatectomy, identifying different preoperative factors between adenoma (intraductal papillary mucinous adenoma [IPMA]) and carcinoma (intraductal papillary mucinous carcinoma [IPMC]).', 'Twelve patients were diagnosed with IPMC. The mean tumor size was 31.9 ± 11.8 mm for IPMA and 35.7 ± 17.1 mm for IPMC (P = .467). No significant differences were found between IPMA and IPMC patients with regard to age, sex, symptoms, and tumor number. The mean diameter of the main pancreatic duct was significantly larger in IPMCs (8.3 ± 5.9 mm) compared with IPMAs (4.7 ± 2.3 mm; P = .011). The mural nodule was a good predictor of malignancy (P = .0002) and was identified as the only independent and significant marker of IPMC in multivariate analysis.'] Is mural nodule in branch duct-type intraductal papillary mucinous neoplasms of the pancreas a marker of malignant transformation and indication for surgery?