Where is a Klatskin tumor located in the hepatobiliary (liver and bile) tree?

Klatskin Tumor Location in the Hepatobiliary Tree

Klatskin tumors are hilar cholangiocarcinomas that occur at or near the junction of the right and left hepatic ducts in the extrahepatic biliary tree. 1

Anatomical Classification

• Klatskin tumors (hilar cholangiocarcinomas) are specifically located at the bifurcation of the common hepatic duct where the right and left hepatic ducts join 1, 2
• These tumors are classified as extrahepatic cholangiocarcinomas despite their proximity to the liver parenchyma 1
• They account for approximately 50-60% of all cholangiocarcinoma cases 1
• The term "Klatskin tumor" is named after Gerald Klatskin who described this specific type of tumor in 1965 3

Diagnostic Features

• Imaging typically reveals dilatation of the intrahepatic bile ducts but normal common bile duct, which is a characteristic finding 4
• Non-union of the right and left hepatic ducts and small solid masses at the hepatic hilum are common sonographic features 4
• The Bismuth-Corlette classification is commonly used to describe the extent of perihilar cholangiocarcinoma based on ductal involvement 5

Anatomical Distinction from Other Cholangiocarcinomas

• Cholangiocarcinomas are broadly classified as either intrahepatic (20-25%) or extrahepatic (75-80%) 1
• Intrahepatic cholangiocarcinomas (also called peripheral cholangiocarcinomas) are located within the hepatic parenchyma 1
• Extrahepatic cholangiocarcinomas include:
  • Hilar/Klatskin tumors (at the confluence of hepatic ducts) 1
  • Distal extrahepatic tumors (in the common bile duct) 1

Clinical Significance

• Klatskin tumors are often diagnosed at advanced stages due to their location and late presentation of symptoms 2
• Surgical resection offers the only chance of cure, but only about 25% of tumors are resectable at diagnosis 3
• Accurate anatomical classification is critical for proper surgical planning and approach 5
• Misclassification of these tumors has been common in cancer registries, with many Klatskin tumors historically being incorrectly coded as intrahepatic tumors 1

Potential Mimics

• Several benign conditions can mimic Klatskin tumors radiologically, sometimes leading to unnecessary radical hepatic resections 6
• Careful evaluation with multiple imaging modalities is essential to differentiate true Klatskin tumors from "Klatskin-mimicking lesions" 6

Understanding the precise location of Klatskin tumors at the junction of the right and left hepatic ducts is crucial for proper diagnosis, staging, and treatment planning in these challenging cases.