This patient presented with severe jaundice for which an MRCP was performed after ultrasound identified biliary obstruction.

On MRCP the CBD is of normal caliber despite severe intrahepatic duct dilatation, therefore the site of obstruction was at the porta.   The ill defined intrahepatic mass in this context was strongly suggestive for a cholangiocarcinoma (Klatskin tumor), which was subsequently proven on histology.

Cholangiocarcinoma is a highly malignant tumor arising from cholangiocytes in the biliary tree, with a poor prognosis.