Table 1.

Features of Subtypes of Cholangiocarcinoma

Feature	Intrahepatic Cholangiocarcinoma (iCAA)	Extrahepatic Cholangiocarcinoma (eCCA)
		Perihilar (pCCA)	Distal (dCCA)
Percent of CCA	10–20%	50–60%	20–30%
Location	Intrahepatic bile ducts	Left, right common hepatic ducts	Common bile duct
Growth pattern	Mass forming or peri-ductal infiltrating or intraductal growth	Peri-ductal infiltrating or intraductal growth
Risk factors	Risk factors seen more commonly in eCCA:  • Choledocholithiasis  • Chronic Pancreatitis  • Primary Sclerosis Cholangitis Risk factors seen more commonly in iCCA:  • Cirrhosis  • Viral Hepatitis (HBV, HCV)  • Liver Flukes (Opisthorchis viverrini, Clonorchis sinensis)  • Alcohol consumption  • Asbestos General Risk factors:  • Diabetes Mellitus type 2  • Obesity  • Cigarettes smoking
Presentation	Weight loss, abdominal pain, nonspecific symptoms	Biliary obstruction, jaundice, abdominal pain, weight loss
Detectable genetic abnormalities (* = FDA-approved targeted therapy)	FGFR Alterations (10–20%)* IDH1 Mutations (15–20%)*	KRAS mutations (30–45%) ERBB2 (HER2) and ERBB3 alterations (10–15%)
	BRAF alterations (3–5%) Homologous Recombination Deficiency – DNA Repair Genes (ATM, BRCA, PLAB2, BAP1, ARID1A, etc) (5–15%) MSI-high/dMMR (2–5%)*