Morphological classification of intraductal papillary neoplasm of the bile duct

To investigate the morphological classification of intraductal papillary neoplasm of the bile duct (IPNB), as well as morphological differences between IPNB without mucin secretion (IPNB-NM) and IPNB with mucin secretion (IPMN-B).

Eighty-one patients with IPNB were retrospectively analysed. Imaging examinations included computed tomography (CT), magnetic resonance imaging (MRI), gadolinium-ethoxybenzyl-diethylenetriaminepentaacetic acid (Gd-EOB-DTPA)-enhanced MRI and positron emission tomography-computed tomography (PET-CT). According to the morphology of tumours and extent of bile duct dilations, IPNB was classified into seven types: I, upstream-ductectatic type; II, typical type; III, superficial-spreading type; IV, no-mass-forming type; V, intrahepatic-cystic type; VI, extrahepatic-cystic type; and VII, infiltrating type.

Thirteen IPNB-NM patients comprised type I (11 cases), type II (1 case) and type VII (1 case); 68 IPMN-B patients comprised type I (2 cases), type II (30 cases), type III (6 cases), type IV (11 cases), type V (13 cases), type VI (2 cases) and type VII (4 cases). Bile duct dilations were more severe in IPMN-B than in IPNB-NM. PET-CT and Gd-EOB-DTPA-enhanced MRI clearly demonstrated the extension of infiltrating IPNB.

IPNB can be classified into seven morphological types. IPNB-NM and IPMN-B have different morphological features.

• IPNB can be classified into seven morphological types. • IPNB-NM and IPMN-B have different morphological features. • Enhanced CT and MRI can display different types of IPNB. • Morphological classification of IPNB facilitates management of the disease.