Imaging description

Peribiliary cysts are small (2–20 mm) thin-walled non-communicating retention cysts of the serous glands adjacent to the intrahepatic bile ducts [1,2]. If numerous and contiguous, these periductal cysts result in an appearance of periportal fluid-filled tubes that may mimic biliary dilatation (including Caroli's disease) or periportal edema (Figures 22.1 and 22.2) [3–6].

Importance

Peribilary cysts are usually inconsequential, and only matter insofar as they mimic more serious pathology or may be markers of associated underlying disease. Rarely, peribiliary cysts may cause biliary obstruction [7, 8].

Typical clinical scenario

Peribiliary cysts usually occur in patients over 50 and are reportedly commoner in men [3]. They may be idiopathic or secondary to adult polycystic disease (Figures 22.3 and 22.4), cirrhosis, idiopathic portal hypertension, extrahepatic biliary obstruction, systemic infection, or liver metastases [9].

Differential diagnosis

While peribiliary cysts can closely mimic biliary dilatation, close inspection may show that the periportal findings are on both sides of the portal vein branches (Figures 22.1 and 22.4), in contrast to dilated bile ducts which are only visible on one side of the portal vein branches. CT cholangiography can elegantly confirm the diagnosis by opacifying the bile ducts and documenting that they are distinct to the peribiliary cysts (Figures 22.1 and 22.2) [3].