THE TODANI SUBTYPES FOR CHOLEDOCHAL CYSTS: TIME TO CONSIDER RECLASSIFICATION
Rejoice F. Ngongoni*, Huda A. Muhammad, Jonathan DeLong, George A. Poultsides, Byrne Lee, Matias Bruzoni, Brendan Visser, Monica M. Dua
Stanford University School of Medicine, Stanford, CA
Introduction: Choledochal cysts (CC) are rare congenital dilations of the biliary tree. CC are categorized into 8 anatomical alphanumeric subtypes using the Todani Classification. The different subtypes are associated with varying levels of cancer risk or liver disease and the surgical management is based on anatomical location. Although this classification has been in use for over four decades, it is challenging to remember, making it less practical for clinical use. Additionally, not all CC fit into this classification system. In this study, we aim to show that the Todani Classification is subject to interpretation and does not comprehensively describe choledochal cysts.
Methods: We conducted a retrospective cohort study of patients who underwent surgical management of a choledochal cyst between 1979 and 2022. Pediatric (<18years) and adult (≥18years) patients were included. Patient demographic data, perioperative information, and morphologic details on biliary anomalies were obtained by retrospective chart review of preoperative radiologic summaries, operative reports, and clinical notes. Descriptive statistical analysis was performed.
Results: A total of 104 patients were included of which 57 (54.8%) were pediatric patients (<18years old) and 81 (77.9%) were female. The median age for the pediatric cohort was 2.8 years while that of the adult cohort was 38.9 years. The most common presenting symptom was pain in 59 (56.7%) patients. The most common preoperative Todani classification was Type I which was present in 56 (53.8%) patients followed by Type IV in 14 (13.5%) patients. Of the 29 (27.9%) patients who were assigned multiple classifications preoperatively, 92.8% of them were pediatric. Computer tomography scan or cholangiogram was obtained in 37 (64.9%) pediatric patients and 43 (91.5%) adult patients, preoperatively. Despite this, there was still discordance between preoperative imaging and intraoperative classification in 40 (38.5%) patients. Eight cases did not fit into the other Todani classifications i.e., Type II to V, and comprised only 7.7% of the cohort (Table). In 15 (14.4%) patients, Types I and IV were used interchangeably despite clear assessment of radiologic imaging.
Conclusion: The current Todani classification of CC that is based purely on the location of cystic dilation is confusing and leads to false grouping of different anomalies of the biliary tree. This is especially true of Type I and IV which can be considered a variation of the same pathology just with different levels of intrahepatic involvement requiring the same surgical management. The Todani classification also does not incorporate all possible choledochal cysts. A new system to classify these CC that is simple and based on reproducible clinical features would eliminate ambiguity and allow standardized reporting for comparable lesions to assess true cancer risk.
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