Diagnostic Ultrasound - Abdomen and Pelvis

Cholangiocarcinoma
TERMINOLOGY
Synonyms
• Cholangiocellular carcinoma or bile duct adenocarcinoma
Definitions
• Malignancy that arises from intrahepatic bile duct (IHBD)or
extrahepatic bile duct epithelium
IMAGING
General Features
• Best diagnostic clue
○ Intra- or extrahepatic bile duct mass with upstream bile
duct dilatation
• Location
○ Distribution in different segments of biliary tree
– Distal common bile duct (CBD): 30-50%, most
common extrahepatic location
– Proximal CBD: 15-30%
– Common hepatic duct (CHD): 14-37%
– Confluence of hepatic ducts (Klatskin tumor): 10-26%
– Isolated right or left IHBD: 8-13%
– Cystic duct: 6%
○ Classification based on anatomy or radiography
– Peripheral (10%): Intrahepatic; proximal to secondary
biliary radicles
– Hilar (50%): Klatskin tumor; confluence of hepatic
ducts
– Distal (40%): Extrahepatic; distal CBD
• Size
○ Intrahepatic mass: A few cm up to 20 cm
○ Extrahepatic: Typically present when smaller
• Morphology
○ Classification by Liver Cancer Study Group of Japan
– Mass-forming type
– Periductal-infiltrating type
– Intraductal-growing type
Ultrasonographic Findings
• Grayscale ultrasound
○ Intrahepatic cholangiocarcinoma
– Mass with ill-defined margin, mixed and
heterogeneous echotexture
– Isolated thickening of IHBD or intraductal mass, with
upstream ductal dilatation
○ Hilar cholangiocarcinoma (Klatskin tumor)
– Dilatation of intrahepatic ducts without extrahepatic
ductal dilatation
– Apparent nonunion of dilated right and left IHBDs
– Primary tumor may not be discernible, or appears as
small infiltrative iso-/hyperechoic mass in hilar region
– Nodular or polypoid mass in bile ducts
– Mass effect, invasion of portal vein and hepatic artery
○ Extrahepatic cholangiocarcinoma
– Dilatation of intrahepatic and proximal extrahepatic
bile duct
□ Primary tumor often undetectable due to its deep
location
– Ill-defined, solid, heterogeneous mass within or
surrounding duct at point of obstruction
□ May be exophytic: Heterogeneous mass arising
from bile duct
□ May be intraluminal: Polypoid iso-/hyperechoic
mass within bile duct
○ Other signs of malignancy
– Infiltration of liver parenchyma
– Lymphatic spread; commonly to porta hepatis,
paraceliac and peripancreatic lymph nodes
– Liver metastases
Radiographic Findings
• Cholangiography (PTC/ERCP)
○ Intraductal filling defect with upstream ductal dilatation
○ Ductal wall irregularity and shouldering
○ "Missing duct" sign: Unopacified segmental IHBDs
upstream to tumor (ERCP)
○ Infiltrating type: Frequently long, rarely short concentric
focal stricture
○ Klatskin tumor: Nonunion of left and right IHBDs
CT Findings
• NECT
○ Intrahepatic/hilar: Peripheral hypodense lesions with
IHBD proximal to obstruction
○ Extrahepatic: Large growth (seen as hypodense mass)
and IHBD dilatation
• CECT
○ Arterial phase: Peripheral enhancement with
progressive, central patchy enhancement and IHBD
dilatation
○ Portal venous phase: Moderate enhancement of
thickened bile duct wall, vascular invasion,
lymphadenopathy
○ Delayed phase (10-15 min): Persistent enhancing tumor
due to fibrous stroma
MR Findings
• T1WI:Iso-/hypointense
• T2WI:Hyperintense periphery (viable) and hypointense
center (fibrosis)
• T1WI C+:Superior to CT in detecting small hilar tumors,
intrahepatic and periductal tumor infiltration
• T1WI FS: Tumor of intrapancreatic portion of CBD seen as
hypointense against hyperintense pancreatic head
• MRCP: Reveals site of obstruction and extension of tumor
growth
Imaging Recommendations
• Best imaging tool
○ US: Detection and initial assessment of level and cause of
biliary obstruction
○ ERCP/MRCP: Extent of biliary ductal involvement
○ CECT/CEMR: More detailed tumor extent (liver invasion,
porta hepatis involvement, regional nodal metastases)
DIFFERENTIAL DIAGNOSIS
Pancreatic Head Adenocarcinoma
• Irregular hypoechoic mass in pancreatic head on US
• Abrupt obstruction of pancreatic duct &/or distal CBD
• Early invasion of celiac axis and superior mesenteric vessels
common
• Obliteration of retropancreatic fat
Diagnoses: Biliary System
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