Biliary intraepithelial neoplasia (BilIN) is frequently found in surgical margins of biliary tract cancer resection specimens but has no clinical implications.

Biliary tract cancers are aggressive tumors of which the incidence seems to increase. Resection with cancer-free margins is crucial for curative therapy. However, how often biliary intraepithelial neoplasia (BilIN) occurs in resection margins and what its clinical and therapeutic implications might be is largely unknown.