Isolated Right Hepatic Duct Biliary Cyst With a Literature Review: Is It Time to Expand the Todani Classification?

Biliary tract cysts are congenital intrahepatic and/or extrahepatic cystic dilatations of the biliary system. Todani classified the biliary tract cysts into five categories. However, solitary intrahepatic biliary tract cysts are rare. With the advancement of better imaging modalities over the decades, new cases have been reported that do not fit into the original Todani classification of biliary duct cysts. Hence, we propose an expansion of the Todani classification to include the uncommon variants.