Current problems with intrahepatic bile duct stones in Japan--congenital biliary malformations as a cause

BACKGROUND/AIMS: In patients with primary intrahepatic bile duct stones, strictures of the biliary duct are often present, but the relationship between these strictures and the formation of the stones remains controversial. Intrahepatic bile duct carcinoma in association with intrahepatic bile duct stones has recently been reported. The present study attempted to ascertain whether bile stasis induced by congenital biliary strictures is the basis for the formation of stones and occurrence of carcinoma. MATERIALS AND METHODS: We analyzed the location of strictures in 58 patients with strictures in the upper portion of the biliary tract including 38 patients with intrahepatic bile duct stones and 9 with intrahepatic bile duct carcinoma. The cell cycle of epithelial cells from the intrahepatic bile duct were analyzed with using proliferating cell nuclear antigen, which is a immunohistochemical staining method. RESULTS: Fifty six of 58 patients had congenital cystic dilatation of the common bile duct (two infant type and 54 adult type). Thirty eight patients had intrahepatic bile duct stones proximal to the strictures at the hepatic hilum. The location of the strictures were classified into four types. Nine patients had intrahepatic bile duct carcinoma and eight of the 9 carcinomas coexisted with intrahepatic bile duct stones. In the nine patients with intrahepatic bile duct carcinoma, the expression of proliferating cellular nuclear antigen (PCNA) in the carcinoma and the normal bile duct epithelium adjacent to the carcinoma was higher than that of patients with hepatocellular carcinoma without anomaly of the biliary duct. CONCLUSION: Considering the location of the strictures and clinical features, the strictures may have been formed congenitally. Furthermore, adult type cysts of the common bile duct with strictures in the upper portion of the biliary tract are thought to be the basis for the formation of primary intrahepatic bile duct stones. The most appropriate treatment for intrahepatic bile duct stones is thus suggested to be removal of the affected hepatic segment including the region of strictures, combined eventually with hepaticoenterostomy.