Choledochal Cyst

Choledochal cysts, or dilatation of the common bile duct, were fi rst reported by Douglas in 1852. The condition is a relatively rare abnormality with an estimated incidence in Western populations of 1 in 13,000– 15,000. However, this condition is far more common in the East, with rates as high as 1 per 1,000 having been described in Japan. The etiology remains unknown, but choledochal cysts are likely to be congenital in nature. The pathologic features of the condition frequently include an anomalous junction of the pancreatic and common bile ducts (pancreaticobiliary malunion: PBMU), intrahepatic bile duct dilatation with or without downstream stenosis, and various degrees of hepatic fi brosis.

Choledochal cysts are usually classifi ed into three groups, based on anatomy. However, other forms and subgroups have been described, based on the cholang-iographic fi ndings of intrahepatic ducts or pancreatico-biliary malunion (PBMU), i.e., the so-called long common channel. Based on our experience, we prefer to classify choledochal cysts into groups associated with presence or absence of PBMU (Fig. 56.1). The majority of choledochal cysts are choledochal cysts with PBMU, and choledochal cysts without PBMU are extremely rare. Thus, the following comments are related primarily to cystic, fusiform, or forme fruste choledochal cysts (FFCC).