Cystic dilatation of the cystic duct: a type 6 biliary cyst.

Choledochal cysts of the cystic duct are extremely unusual and only single case reports are documented in the literature. The widely used Todani classification does not include such type of lesions. We present a case of a young girl with a cystic duct choledochal cyst diagnosed preoperatively and confirmed intraoperatively. Due to the site and mass effect of the cyst, excision of the lesion included a part of bile duct. Reconstruction was achieved by Roux-en-Y hepaticojejunostomy. While such lesions are extremely rare, they do occur and need to be recognized as a separate entity in the Todani classification.