Intraductal papillary neoplasm of the bile duct
Intraductal papillary neoplasm of the bile duct (IPNB) is a pre-invasive biliary tree neoplasm considered to be a precursor of cholangiocarcinoma.
IPNBs have been reported to be more frequent in Asia, in regions where hepatolithiasis and clonorchiasis are endemic 2,6. They account for 10 to 30% of all bile duct tumors in countries such as Japan, China, and Korea, compared to ~9% in Western countries 2.
Other risk factors for IPNBs 2:
- primary sclerosing cholangitis (PSC)
- biliary tree malformations
- choledochal cysts
- familial adenomatous polyposis (Gardner syndrome)
Reported symptoms include abdominal pain and jaundice.
IPNB is a counterpart for the intraductal papillary mucinous neoplasm of the pancreas (IPMN), with both showing intraluminal growth, same histological subtypes, and the association with mucin hypersecretion 1-4.
Although they potentially affect any segment of the biliary tree, IPNBs are more frequently found involving the intrahepatic ducts or at the hepatic hilum and, for unclear reasons, most commonly within the left-sided ducts 2.
On gross specimens, they present as solitary or multiple papillary lesions within a dilated bile duct 2.
Different from the pancreatic IPMN, which are commonly lined by mucinous epithelium, IPNBs are lined by biliary epithelium 4. There is a papillary proliferation of the atypical epithelial cells with central fibrovascular cores, as well as mucinous cells 1,2.
Histological subtypes are 1-6: