Biliary intraepithelial
neoplasia (
BilIN) is a precursor lesion of hilar/perihilar and
extrahepatic cholangiocarcinoma.
BilIN represents the process of multistep cholangiocarcinogenesis and is the biliary counterpart of pancreatic intraepithelial
neoplasia (PanIN). This study was performed to clarify the histological characteristics of
BilIN in relation to PanIN. Using
paraffin-embedded tissue sections of surgically resected specimens of
cholangiocarcinoma associated with
BilIN and pancreatic ductal
adenocarcinoma associated with PanIN, immunohistochemical staining was performed using primary
antibodies against MUC1, MUC2, MUC5AC,
cyclin D1, p21, p53, and S100P. For
mucin staining,
Alcian blue pH 2.5 was used. Most of the molecules examined here showed similar expression patterns in
BilIN and PanIN, in which their expression tended to increase along with the increase in atypia of the epithelial lesions. Significant differences were observed in the increase in
mucin production and the expression of S100P in PanIN-1 and the expression of p53 in PanIN-3, when compared with those in
BilIN of a corresponding grade. These results suggest that
cholangiocarcinoma and pancreatic ductal
adenocarcinoma share, at least in part, a common carcinogenic process and further confirm that
BilIN can be regarded as the biliary counterpart of PanIN.