An unclassified congenital bile duct cyst.

Congenital bile duct cysts are rare in adulthood. The most frequently used classification was proposed by Todani in 1977. However, in rare cases, not all the bile duct cysts are suitable to this classification. Hereby, we describe the case of an unclassified and very rare form of congenital bile duct cyst--isolated cystic duct cyst. En-block resection of the cyst, along with gallbladder, is the treatment of choice. Although exceptional, cystic duct cysts should be included in Todani classification so that the surgeons to be aware for this variation.