Biliary papillomatosis with the point mutation of K-ras gene arising in congenital choledochal cyst.

Biliary papillomatosis is a rare entity. A case of biliary papillomatosis associated with congenital choledochal cyst and intrahepatic gallstones is reported here. Percutaneous transhepatic cholangioscopy revealed multiple papillary lesions of the right intrahepatic duct and the common bile duct. Microscopically, the papillary mucosal lesion showed papillary proliferations of bile duct epithelial cells with mild atypia. Furthermore, a point mutation at codon 12 of the K-ras oncogene was found in the papillary lesion. To the best of our knowledge, this is the first case of biliary papillomatosis arising in congenital choledochal cyst. Although the pathogenesis of biliary papillomatosis in our case was unclear, biliary irritation associated with choledochal cyst may be related to biliary papillomatosis with point mutation at codon 12 of K-ras gene.