List of abbreviations:
IPMN-B: Intraductal papillary mucinous neoplasm of bile duct
CEA: carcinoembryonic antigen
CA 19-9: Cancer antigen 19-9
CECT: Contrast-enhanced computed tomography
COPD: chronic obstructive airway disease
OS: ovarian-like stroma
IOC: Intraoperative cholangiography