Smallest Todani's type II choledochal cyst

A choledochal cyst is defined as an isolated or combined congenital dilation of the extra hepatic or intrahepatic biliary tree. Todani and colleagues proposed the five types of congenital choledochal cysts which have gained widespread acceptance. Type II choledochal cyst, a diverticulum of common bile duct, is rarest, and most reported cases of Type II were as large as several centimeters in size. We herein report the case of a small Type II choledochal cyst which was resected at pancreatoduodenectomy for carcinoma of the papilla of Vater. A 58-year-old Japanese male was referred to our hospital for the evaluation of jaundice. Preoperative cholangiogram via the percutaneous transhepatic biliary drainage tube revealed a complete obstruction at the narrow terminal segment. Furthermore, a small diverticular protrusion was demonstrated on the lower part of the common bile duct. The resected specimen showed a 2.2 x 1.7 x 1.2 cm carcinoma of the major papilla, and a deep, 2 mm in diameter and 5 mm in depth, depression on the posterior wall of the common bile duct. The anomalous pancreatobiliary duct was not seen. The deep depression was confirmed microscopically to penetrate the fibromuscular layer of the common bile duct and diagnosed as a Todani's Type II choledochal cyst. To our knowledge, the current case is the smallest Type II choledochal cyst which was completely resected.