A 62-year-old man with primary sclerosing cholangitis presents with 4 weeks of progressive painless jaundice, pruritus, and weight loss. Bilirubin is 14 mg/dL (direct predominant), ALP 720 U/L, and CA 19-9 880 U/mL. Contrast CT shows dilated intrahepatic ducts with abrupt cut-off at the hepatic hilum, a small enhancing soft-tissue mass at the confluence of right and left hepatic ducts extending into the right secondary branches, right hepatic lobe atrophy, and a collapsed non-distended gallbladder. The lesion marked **B** in the diagram represents this tumor. According to the Bismuth-Corlette classification, what is the type of this hilar cholangiocarcinoma?

Question

Accepted Answer

B. Type IIIA — tumor extending into right secondary hepatic radicles. ## Why Type IIIA is right

The Bismuth-Corlette classification stratifies hilar cholangiocarcinomas (Klatskin tumors) by the extent of involvement of the hepatic duct confluence and secondary radicles. Type IIIA specifically denotes a tumor at or near the confluence of the right and left hepatic ducts that extends into the RIGHT secondary hepatic radicles. In this case, the CT imaging explicitly describes the mass at the confluence extending into the right secondary branches, with associated right hepatic lobe atrophy—the classic presentation of Type IIIA disease. This classification is critical for surgical planning, as Type IIIA tumors typically require right hepatic trisectionectomy with caudate lobectomy to achieve R0 resection (Blumgart/Bismuth-Corlette classification, standard in hilar cholangiocarcinoma management).

## Why each distractor is wrong

- **Type I**: Type I tumors arise below the confluence with the confluence itself remaining intact. This case has a mass directly AT the confluence extending into secondary radicles, making it at least Type II or higher.
- **Type II**: Type II tumors involve the confluence but do not extend into secondary radicles. This patient's tumor clearly extends into the right secondary branches, which upgrades it to Type IIIA.
- **Type IV**: Type IV disease involves bilateral secondary radicles (both right AND left) or multifocal tumors. This case involves only the right secondary radicles, making it Type IIIA, not Type IV.

**High-Yield:** Klatskin tumors (hilar cholangiocarcinomas) at the confluence extending into RIGHT secondary radicles = Bismuth-Corlette Type IIIA; LEFT secondary radicles = Type IIIB; BILATERAL = Type IV. Right lobe atrophy + dilated intrahepatic ducts + non-distended gallbladder = classic CT triad.

[cite: Blumgart/Bismuth-Corlette classification for hilar cholangiocarcinoma]

Answer

A. Type IV — tumor involving bilateral secondary radicles or multifocal disease

Answer

C. Type I — tumor below the confluence with confluence intact

Answer

D. Type II — tumor involving the confluence

Explanation

Why Type IIIA is right

Why each distractor is wrong

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