Intrahepatic peripheric mass forming cholangiocarcinoma:

These tumors are usually found when symptomatic as large masses, causing biliar obstruction, proximal biliar dilation and capsular retraction. Hystologically, they have a large desmoplastic component, which is accountable for the enhancement pattern, irregular peripheric on arterial phase and centripetal enhancement on delayed phase images.

Mass forming cholangiocarcinoma can present as a hypodense nodules on basal CT (Fig. 3) on MRI, it had hyperintensity on T2 (fig. 4), and had contrast irregular rim early enhancement (fig. 5) and centripetal delayed phases contrast persistence (fig. 6-7).

Cholangiocarcinoma can also present as large masses with irregular centripetal enhancement, that causes liver capsule retraction and bile duct dilation on contrast enhanced CT (Fig. 8-9).

Intrahepatic periductal cholangiocarcinoma:

This type usually presents with segmentary bile duct dilation or bilateral dilation depending on the location in the biliary tree. On sonography we can see segmental bile duct dilation.On contrast enhanced CT we can find an enhancing nodule (Fig. 10). Minimun intensity reconstruction helps locate the confluence of the bile ducts when there is dilation(Fig 11).

Extrahepatic cholangiocarcinoma:

This type is usually periductal and is characterized by growth along a narrow or dilated bile duct without mass formation. Patients can present with jaundice, abdominal pain and dilation of the intra and extrahepatic bile ducts. Usual sonographic findings are bile duct dilation without identifying the cause, so on most cases, a CT or MRI are needed. On contrast enhanced CT, we can find thickening of the bile ducts that enhance(Fig. 12-13).

Intraductal:

This is a rarer type that slowly grows into the duct and can invade the mucosa, but in a later phase. This tumor may produce dilation of the proximal ducts. Sonographic findings include bile duct dilation with occupation by a castlike image which is often confused with biliary sludge and bile ducts dilation that can be segmental, bilateral, and extrahepatic only, depending on the location on the biliary tree and on the evolution time. Usually extrahepatic lesions develop extrahepatic bile duct dilation before causing intrahepatic dilation (Fig. 16). On contrast enhanced CT we can find occupation of the bile ducts by a mass that enhances on portal and delayed phase(Fig. 17).

In MRCP sequences findings include intraluminal defects and bile duct dilation (Fig.14) and on contrast MRI we can see that these mass enhances (Fig.15).

Differential diagnosis of cholangiocarcinomas can be quite challenging based on the imaging features. Liver masses have a broad differential, including hepatocarcinoma, metastasis, early stages of abscesses, tuberculomas, among others,  while bile duct dilation can be due to intrinsic or extrinsic compression, most commonly gallblader stones, ampulomas, neuroendocrine tumors (Figs. 18-19), metastasis. Chronic cholangitiscan also mimic a cholangiocarcinoma (Fig. 20).