Cystadenoma of the common bile duct demonstrated by percutaneous transhepatic cholangiography.

Benign neoplasms of the extrahepatic biliary tract are uncommon and rarely diagnosed preoperatively. Percutaneous transhepatic cholangiography will demonstrate such lesions, and, if contrast outlines only the wall of the mass, a benign tumor may be suspected. An example of a cystadenoma of the common bile duct demonstrating this principle is presented.