What is the role of CT scanning in the workup of cholangiocarcinoma?

Updated: Apr 13, 2018
  • Author: Mahesh Kumar Neelala Anand, MBBS, DNB, FRCR; Chief Editor: John Karani, MBBS, FRCR  more...
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Answer

Intrahepatic cholangiocarcinomas cannot easily be depicted with cross-sectional imaging. The mass is predominantly hypoattenuating, with irregular margins, and the tumors may be 5-20 cm in size at the time of presentation. The mass is rounded or oval, and images may demonstrate segmental biliary duct dilatation because of obstruction. With the intravenous administration of iodinated contrast material, the mass may demonstrate a variable enhancement pattern. No enhancement, minimal peripheral enhancement, or central enhancement may be depicted. [10, 11]

Delayed enhancement with increasing attenuation may be seen on images in as many as 74% of patients. This pattern of enhancement may be useful in differentiating HCC from cholangiocarcinomas. [12] Hepatocellular carcinoma (HCC) shows an early peak increase in attenuation with a progressive decrease. The overlying liver capsule may be retracted when the lesions are peripheral. A central scar is present in about 30% of patients. Occasionally, peripheral cholangiocarcinomas are resectable when they do not involve the inferior vena cava or the caudate lobe.

The biliary ducts may show intense enhancement in the early phase because of associated chronic bile duct inflammation. Satellite nodules of masses are seen in 65% of patients with intrahepatic tumors. Regional metastatic lymphadenopathy may be present in about 15% of cases involving intrahepatic tumors.

Extrahepatic disease is characterized by dilatation of intrahepatic ducts without extrahepatic duct dilatation. The mass in or surrounding the ducts is visible on CT scans in about 40% of cases. The confluence of the right and left ducts may be obliterated with the loss of sharp distinction. The infiltrating tumors, which grow along the duct, and the intraluminal polypoidal tumors are difficult to detect with CT and may be defined in only 22-25% of cases. Infiltrating tumors are seen as high-attenuating lesions in 22% of cases. Exophytic tumors are larger, and with thin-section imaging, the mass is demonstrable in 100% of cases as a low-attenuating lesion with lobulation. Morphologic changes may occur late in the disease process, with atrophy of the left lobe of the liver compared with the right lobe. The left-sided ducts may be more dilated than the right-sided ducts.

Differentiating the tumor from HCC, especially the fibrolamellar type of HCC, may be difficult because the alpha-fetoprotein (AFP) level is not increased with either tumor.

Differentiating solitary intrahepatic cholangiocarcinoma from HCC is difficult with CT. The presence of satellite nodules suggests cholangiocarcinomas.


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