Figure 10b. Cholangiocarcinoma in a preexisting choledochal cyst. (a) Sagittal US scan through the right lobe of the liver shows a soft-tissue mass (M) within a focal sacculation of the common hepatic duct. gb = gallbladder. (b) Coronal magnetic resonance (MR) cholangiopancreatogram helps confirm the presence of the mass (m).