Risk factors:- Chronic inflammation of the gallbladder, bile ducts, or liver→ Chronic cholangitis, especially primary sclerosing cholangitis (most common risk factor)→ Chronic liver disease- Congenital abnormalities of the bile ducts (e.g., choledochal cysts, congenital hepatic fibrosis)- Parasitic infection of the biliary tracts (e.g., Clonorchis sinensis)- Diabetes, obesity, and alcohol consumption

Classification: Bismuth- Extrahepatic cholangiocarcinoma are most common (80% of cases): further divided into perihilar and distal extrahepatic cholangiocarcinomas- Intrahepatic cholangiocarcinoma involves the intrahepatic bile ducts.

Clinical features:- Intrahepatic bile duct carcinoma→ Nonspecific abdominal symptoms (e.g., weight loss, nausea) → Dull right upper quadrant (RUQ) pain→ Signs of cholestasis are rare- Extrahepatic bile duct carcinoma→ Nonspecific symptoms (e.g., weight loss, fever) → Signs of cholestasis: jaundice, pale stools, dark urine, pruritus, hepatomegaly→ Possibly a positive Courvoisier's sign