Percy, thanks for doing the housekeeping!
A word of caution about the second link:
Is preoperative histological diagnosis necessary for cholangiocarcinoma?
The article was published in 2008. The authors reviewed the literature up to July 2007. They reached the conclusion that positive biopsy is not required to diagnose extrahepatic CC. That was before the emergence of SpyGlass exam. I'm not sure if SpyGlass biopsy is accurate enough to change the conclusion reached in the article.
Here's another good article closely related to the other two.
Endoscopic diagnosis of extrahepatic bile duct carcinoma: Advances and current limitations
Here's another article that looks at the issue of biopsy before surgery. The section on extrahepatic CC reviews several benign strictures that may look very similar to ECC.
Is preoperative histological diagnosis necessary before referral to major surgery for cholangiocarcinoma?
Note: "histological diagnosis" refers to positive biopsy that firmly confirms CC.