Malignancy arising from intrahepatic bile duct (IHBD) or extrahepatic bile duct epithelium

Best diagnostic clue: Intra- or extrahepatic bile duct mass with upstream bile duct dilatation

Intrahepatic cholangiocarcinoma

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  Mass with ill-defined margin, heterogeneous echotexture

  
  
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  Arise distal to 2nd-order bile ducts

  
  
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  Isolated thickening of IHBD or intraductal mass with upstream ductal dilatation

  
  
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  May see associated capsular retraction of liver

Hilar cholangiocarcinoma

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  Dilatation of IHBDs without extrahepatic ductal dilatation

  
  
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  Nonunion of right and left hepatic ducts due to obstructing mass

  
  
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  Primary tumor may not be discernible or appears as small, infiltrative iso-/hyperechoic mass in hilar region

  
  
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  Nodular or polypoid mass in bile ducts

Extrahepatic cholangiocarcinoma

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  Proportional bile duct dilatation

  
  
  
  
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    Primary tumor often undetectable due to deep location

  
  
  
  
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  Ill-defined, solid, heterogeneous mass within or surrounding duct at point of obstruction

  
  
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  Exophytic heterogeneous mass from bile duct

  
  
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  Polypoidal intraluminal tumor visible as iso-/hyperechoic mass within bile duct

Pancreatic head adenocarcinoma

Choledocholithiasis

Recurrent pyogenic cholangitis

Primary sclerosing cholangitis

Porta hepatis tumor

Pathogenesis: Biliary intraepithelial neoplasm is considered premalignant lesion

Rule out other pancreatobiliary pathology causing biliary obstruction

Long focal extrahepatic biliary stricture, irregular ductal wall, stenosis, and prestenotic biliary ductal dilatation

Look for capsular retraction, biliary ductal dilatation, or abrupt cut-off of dilated bile ducts