Type I tumors are found below the confluence of the left and right hepatic ducts.

Type II tumors reach the confluence of the left and right hepatic ducts.

Type IIIa and IIIb tumors occlude the common hepatic duct and either the right or the left hepatic duct, respectively.

Type IV tumors are multicentric or they involve the confluence and both the right and left hepatic ducts. A combined anatomic–morphologic classification is useful for patient management and can provide consistency in clinical or epidemiologic studies. Tumors are shown in (B) and (C) in yellow