Figure 28b. Papillary adenoma in a preexisting choledochal cyst. (a) Sagittal US scan through the porta hepatis shows an eccentric mass (m) within a biliary diverticulum. (b) Coronal MR cholangiopancreatogram helps confirm the presence of the mass (m). Cholangiocarcinoma in a choledochal cyst was proved at histopathologic analysis.