Objective Peribiliary cysts are usually benign, although severe complications and mortality may occur, and they may be confounded with other diseases. No classification delineating their different characteristics exists.

Design We performed a systematic review of the frequency and clinical manifestations of peribiliary cysts. Two reviewers identified studies after searching multiple databases on 2 August 2017.

Results These cysts were prevalent in cirrhosis (9%). A total of 135 patients were reported in 72 papers with sufficient clinical data (10 countries, 65% from Japan, median age 63 years (range: 4–88), and 80% were males). Symptoms were present in 70%. Misdiagnosis occurred in 40%, and 33% underwent therapeutic misadventures. Cysts were solitary in 10%. Obstructive features and cholangitis were observed in 36% and 12.5%, respectively. Cysts progression was observed in 37.5% over a median of 18 months. Mortality was 24%, mostly due to cirrhosis. A classification framework is proposed, wherein type I includes hepatic, type II extrahepatic and type III mixed hepatic and extrahepatic cysts, each having distinct features. Specifically, type II was more frequent in females, solitary, without cirrhosis, presenting with obstructive jaundice, more difficult to diagnose and required more surgical interventions (all p<0.05).

Conclusion Although rarely studied in the literature, peribiliary cysts were frequent in studies designed to evaluate their prevalence, and were mostly asymptomatic. Inaccurate diagnosis, therapeutic misadventures, cysts progression and cysts-related complications are frequent. In a novel classification framework based on location, extrahepatic peribiliary cysts have distinct characteristics and require a special approach for diagnosis and management.