Peribiliary cysts on MRI: review of imaging features and associated clinical features.

purposePeribiliary cysts (PBC) are benign cystic lesions adjacent to intrahepatic and extrahepatic bile ducts, most often seen in chronic liver disease, and may mimic other cystic biliary entities. We evaluated MRI features of PBC and their clinical associations.

methodsWe retrospectively reviewed 1708 consecutive patients who underwent liver MRI at our institution (2021-2022). Imaging and clinical data were assessed for PBC, including location (intra-/extrahepatic), distribution, size, and associated bile duct dilatation. Group comparisons used descriptive statistics and hypothesis testing (p < 0.05). Correct identification of PBC in the original MRI report was recorded. Interval change on follow-up MRI was assessed.

resultsPBC were identified in 35/1708 patients (2.0%); 77.1% were male, mean age 63.5 years (SD 12.4). Cysts were predominantly intrahepatic (97.1%) with bilobar involvement in 80.0%. Median cyst size was 9 mm (range 2-34 mm). Concomitant bile duct dilatation was present in 25.7%. PBC were significantly associated with cirrhosis (60%; p < 0.001). Malignancy was present in 42.8% of patients with PBC versus 35.9% without PBC (p = 0.3797). Cyst progression was observed in 59.3% of patients with follow-up MRI. PBC were correctly identified in the original report in 10/35 cases (28.6%).

conclusionPBC are uncommon but are strongly associated with chronic liver disease and typically show an intrahepatic, bilobar, predominantly central peribiliary distribution. They are frequently underrecognized on baseline reporting, and progression is common on follow-up. Awareness of typical MRI patterns may improve differentiation from mimickers; further studies should clarify clinical significance and prognostic implications.