Factors of biliary carcinogenesis in choledochal cysts.

The long-term complications of choledochal cysts include malignant degeneration of the epithelial lining of the biliary tract. Possible factors leading to malignant degeneration were examined by measuring amylase levels in the biliary tract, intraoperative biliary manometry and a histopathological study. 27 patients, 1 to 13 years of age, with choledochal cysts, were studied over a 13-year period. Amylase levels in the bile of choledochal cysts and the gallbladder were measured. The pressure profile of the biliary tract was recorded as the probe was withdrawn from the sphincter of Oddi (SO) to the distal end of the common bile duct. Hyperplasia of the gallbladder mucosa and malignancy of the biliary tract were investigated. Patients with high levels of biliary amylase had higher pressure differences between the SO and the duodenum than those with low levels of biliary amylase. The incidence of mucosal hyperplasia of the gallbladder mucosa was significantly higher in the fusiform type than in the cystic type. Adenocarcinoma in a cystic choledochal dilatation was found in a 12-year-old girl with high amylase levels. The cause of regurgitation of pancreatic juice into the biliary system might be due to a high pressure difference between the SO and the duodenum in addition to the lack of sphincter function at the abnormal junction of the pancreaticobiliary ductal system. Early diagnosis and surgical treatment to prevent the regurgitation leading to hyperplasia and malignancy of the biliary tract are important for children with choledochal cysts.