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A 52-year-old man with a history of alcohol-induced, Child-Pugh C10 cirrhosis was referred to our center for pretransplantation imaging screening. Initial blood tests revealed moderate hepatic cytolysis and cholestasis, with an elevated serum bilirubin level at 139 mmol/L (normal range, ≤17). Doppler ultrasonography confirmed features of cirrhosis with portal hypertension and showed pseudocystic dilatation of intrahepatic bile ducts.

Magnetic resonance cholangiopancreatography (MRCP) was then performed and demonstrated small cysts on both sides of the portal veins, which did not communicate with the bile ducts. There was no evidence of obstructive jaundice. Such magnetic resonance imaging (MRI) findings were consistent with the diagnosis of peribiliary cysts (Fig. 1), secondarily confirmed on the liver explant (Fig. 2).

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Figure 1. MRI and MRCP of the liver. Axial T2-weighted images (A) without and (B) with fat suppression confirm the cystic nature of the structure with the high-intensity signal (arrowheads) along the portal vein (white arrow). Note features of cirrhosis with marked hyperintense areas of confluent fibrosis (*). (C) Three-dimensional MRCP disproves the possibility of biliary dilatation and revealed that these tiny cysts do not communicate with the biliary tree. Small cysts (arrowheads) are well observed anterior and dorsal to the left and right hepatic ducts, confirming the diagnosis of peribiliary cysts.

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Figure 2. Fixed gross specimen of the explanted liver showing small, unilocular cysts (*) adjacent to, but independent of, the biliary ducts (arrow). Extensive periportal fibrosis can also be observed.

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Peribiliary cysts were first described in 1984 by Nakanuma et al.1 as serous cysts involving the hepatic hilum and large portal tracts without communication with the biliary tree. The cystic wall is composed of a single layer of columnar or cuboidal epithelium. They represent cystic dilatation of the extramural glands in the periductal connective tissue2 and are usually found incidentally in patients with advanced liver disease, with almost all having severe portal hypertension.3 They may increase in size and number.4

They are usually asymptomatic, although obstruction of the bile ducts may occur.5 The point is that, in patients with a high serum bilirubin level caused by cirrhosis, peribiliary cysts may be misdiagnosed as obstructive jaundice, especially on ultrasound examination.

Positive diagnosis is made on the presence of such cystic dilatation on both sides of the portal veins, whereas dilation of intrahepatic bile ducts usually appears on one side. MRCP6 is a useful, noninvasive technique showing small fluid-filled cavities independent of the biliary tree.

Other differential diagnoses include bile duct hamartomas, Caroli disease, and periportal edema. Bile duct hamartomas are rare, benign malformations of the biliary tract that present as multiple cystic lesions that do not communicate with the biliary tree on MRCP, affecting all the liver without periportal distribution. MRCP in Caroli disease displays multiple cystic structures of varying size communicating with the biliary system. Periportal edema is characterized by a nonspecific fluid infiltration of periportal spaces and may occur in acute hepatitis, hypoalbuminemia, ascites, cirrhosis, veno-occlusive disease, and heart failure.

This not so rare condition should be considered on imaging in the presence of cystic structures adjacent to the biliary tree in cirrhotic livers.

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