Adult choledochal cysts: current update on classification, pathogenesis, and cross-sectional imaging findings

Approximately 20% of choledochal cysts (CC) present in adult patients and they are commonly associated with a high risk of complications, including malignancy. Additionally, children who underwent internal drainage procedures for CCs can develop complications during adulthood despite treatment. Concepts regarding classification and pathogenesis of the CCs have been evolving. While new subtypes are being added to the widely accepted Todani classification system, simplified classification schemes have also been proposed to guide appropriate management. The exact etiology of CCs is currently unknown. The two leading theories involve either the presence of an anomalous pancreatico-biliary junction with associated reflux of pancreatic juice into the biliary system or, more recently, some form of antenatal biliary obstruction with resulting proximal bile duct dilation. Imaging studies play an important role in the initial diagnosis, surgical planning, and long-term surveillance of CCs.