Fig. 7. A 63-year-old man, with intrahepatic cholangiocellular carcinoma.

This is an example of Klatskin tumor, central subtype. A. B-mode ultrasonography (US) shows dilated bile ducts, and a "stop" at the level of the hepatic ducts (bifurcation), with a badly defined mass. This is called an invisible tumor in ultrasonography. B. On color Doppler ultrasonography, it is easy to observe the dilated bile ducts versus blood vessels. C-F. Contrast-enhanced ultrasonography (CEUS) evaluation shows a nodule measuring 4.7×3.2 cm, presenting arterial enhancement with early and marked washout, which becomes more pronounced in the late phase. The nodule, measuring 4.7×3.2 cm, shows arterial enhancement with early and marked washout.