General characteristics

Cholangiocarcinoma is a biliary malignancy of older patients (>50 years). Patients usually present with jaundice and weight loss. Three types of cholangiocarcinomas can be differentiated based on the anatomical distribution: the peripheral (or intrahepatic) type arising from Primary sclerosing cholangitis (PSC). Maximum- intensity projection (MIP) from high-resolution T2- weighted three-dimensional fast spin-echo imaging in two patients with primary sclerosing cholangitis. Focal bile-duct irregularities, stenosis, and interruptions can be appreciated in all parts of the intrahepatic and extrahepatic biliary system (a arrows). High- and low-grade stenoses of peripheral bile ducts (b arrows) induce signs of obstruction and dilatation of the bile ducts until far into the liver periphery peripheral bile ducts in the liver, the hilar type (Klatskin tumor) with its origin at the confluence of the right and left hepatic ducts, and the extrahepatic type arising from the main hepatic ducts, CHD or CBD.

Klatskin tumors

Klatskin tumors are usually small-volume, superficial, spreading tumors that result in early biliary obstruction and dilatation of proximal ducts. They show circumferential growth and spread along bile ducts with poor conspicuity on non-contrast MR images. Lobar atrophy of the liver combined with marked biliary dilatation is an associated MRI finding.

Extrahepatic cholangiocarcinomas

Extrahepatic cholangiocarcinomas usually grow in a circumferential pattern similar to Klatskin tumors. They arise in the CBD and result in biliary obstruction in the vast majority of patients. On T1-weighted MR images with or without fat-suppression, cholangiocarcinomas appear mildly to moderately hypointense but may also be isointense relative to liver parenchyma. On T2-weighted images, they are isointense or mildly hyperintense. Thickening of bile duct walls greater than 5 mm is highly suggestive of cholangiocarcinoma. On immediate post-gadolinium images, cholangiocarcinomas are usually hypovascular showing minimal or moderate enhancement that intensifies on delayed images (Fig 6.1.29). A combination of early and late fat-suppressed gadolinium-enhanced images is very helpful to identify these tumors. Fat-suppression also reduces the signal of fatty tissue in the porta hepatis, which improves the conspicuity of cholangiocarcinomas and facilitates the evaluation of the extent of tumor and infiltration into adjacent tissues and organs (Worawattanakul et al. 1998).

Intrahepatic or Peripheral Bile-Duct Carcinoma (Cholangiocarcinoma)

Intrahepatic or peripheral cholangiocarcinoma are terms applied to lesions that originate in the ducts proximal to (i.e., above) the hilum of the liver.

The tumor is frequently large at presentation. Cholangiocarcinoma resembles HCC with moderate high signal intensity on T2-weighted images and low signal intensity on T1-weighted images. Enhancement with gadolinium varies from minimal to intense diffuse heterogeneous enhancement immediately after contrast administration. Minimal enhancement is most commonly observed. Persistent enhancement on delayed images is relatively common (Hamrick et al. 1992).

Malignant tumors of mixed liver cell and bile duct differentiation are rare. Mixed HCC–cholangiocarcinoma may occur, and the imaging appearance is generally indistinguishable from that of HCC.

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