Cholangiocarcinoma
Also known as: bile duct cancer
Cholangiocarcinoma is a malignant tumor arising from the epithelial cells that line the bile ducts. It is usually an adenocarcinoma, tends to present late with painless jaundice, and carries a poor prognosis because it is rarely resectable at diagnosis.
Cholangiocarcinoma arises from cholangiocytes, the epithelial cells lining the biliary tree. The great majority are adenocarcinomas with a dense fibrous stroma, which is part of why they are firm, infiltrative, and difficult to biopsy. Tumors are classified by location: intrahepatic, within the liver; perihilar, at the junction of the right and left hepatic ducts — the classic Klatskin tumor; and distal, in the common bile duct. Perihilar tumors are the most common of the three.
The recognized risk factors share a theme of chronic biliary inflammation. Primary sclerosing cholangitis, often in the setting of ulcerative colitis, is the most heavily tested association. Others include liver fluke infection with *Clonorchis sinensis* or *Opisthorchis viverrini*, congenital choledochal cysts and Caroli disease, chronic hepatitis B or C, cirrhosis, and hepatolithiasis. The historical contrast agent thorotrast is a classic exam association.
Clinically, an extrahepatic tumor obstructs bile flow and produces painless obstructive jaundice with pruritus, pale stools, dark urine, and weight loss; a palpable, nontender gallbladder in a jaundiced patient — Courvoisier sign — suggests malignant obstruction rather than gallstones. Intrahepatic tumors often stay silent longer and present with a liver mass, vague right upper quadrant discomfort, or constitutional symptoms. Laboratory findings show a cholestatic pattern with elevated direct bilirubin and alkaline phosphatase, and CA 19-9 may be elevated but is not specific. Imaging with MRCP or CT defines the extent, and surgical resection or transplantation in selected cases offers the only cure — most patients are diagnosed too late for it.
USMLE Step 1 tests cholangiocarcinoma within gastrointestinal pathology, most often through a vignette pairing long-standing primary sclerosing cholangitis with new painless jaundice and weight loss. Know how to separate it from cholangitis, an acute infection of an obstructed biliary tree that presents with Charcot triad of fever, jaundice, and right upper quadrant pain.
Key takeaways
- Cholangiocarcinoma is a malignancy of bile duct epithelium, usually adenocarcinoma with dense fibrous stroma.
- It is classified as intrahepatic, perihilar (Klatskin tumor), or distal; perihilar tumors are most common.
- Primary sclerosing cholangitis is the most classic risk factor; liver flukes, choledochal cysts, and chronic viral hepatitis also increase risk.
- Extrahepatic tumors typically present with painless obstructive jaundice, pruritus, and weight loss.
- Diagnosis is late in most patients, and surgical resection offers the only chance of cure.