Type I choledochal cysts in adults: natural history and implications for management

Historical pediatric data recommend surgical resection for type I choledochal cysts because of the risk of malignant progression over time (up to 60%). With the widespread use of high-resolution cross-sectional imaging, isolated dilation of the extrahepatic biliary tree has become more frequently observed. The pediatric management strategy for choledochal cysts has been extrapolated to adults, without any specific long-term data. This study aimed to characterize the natural history of choledochal cysts in adults.

We have updated our previously published institutional series. From 1990 to 2023, all adult patients with a radiographic diagnosis of Todani type I choledochal cysts were identified from the endoscopic, radiologic, and surgical databases at a single academic institution. Patient demographics, clinical data, imaging studies, pathology, and management outcomes were reviewed.

A total of 100 patients with a median age of 41 years (range 15-78 years) and male/female ratio of 0.3 were identified. Ninety-three patients underwent surgery, including 83 (89%) with clinical symptoms with or without abnormal serologic liver function test results. Symptoms included biliary colic (62%), pancreatitis (16%), and cholangitis (11%). The median radiographic duct size was 22 mm [range 9-100]. 73% of the patients underwent Endoscopic Retrograde Cholangio-Pancreatography (ERCP) as part of their work-up. An anomalous pancreaticobiliary ductal junction (APBDJ) was identified in 83%, compared to 30% in biliary dilation from other etiology from our historical institutional cohort (p < 0.001). The median time from diagnosis to resection was 7 months (range 0.1-9 years). The cholangiocarcinoma rate was 6% during a median follow-up of 8 years [range 0.5-64yrs]. Five out of 6 (83%) malignant cysts were initially diagnosed during childhood, but were not resected or only bypassed. The overall morbidity after choledochal cyst resection was 50%, with Clavien-Dindo III-IV complications occurring in 40% of the patients. The clinically relevant bile leak rate was 16%, with no predictive features on the multivariate analysis. Bilioenteric anastomotic stricture and symptomatic retained cyst in the intrapancreatic portion of the bile duct requiring reoperation occurred in 24% and 5% of the patients, respectively.

The largest Western series of type I choledochal cysts in adults confirms a lower risk of malignant transformation than previously described, occurring mostly in cysts diagnosed during childhood but not resected at that time. When diagnosed at an older age, the lower risk of cholangiocarcinoma should be weighed against the high risk of short- and long-term biliary complications associated with resection, including biliary fistula, stricture, and recurrent pancreatitis due to retained cysts within the intrapancreatic bile duct.