Abstract
A 58 year-old woman with a gallbladder polyp was eventually diagnosed after hospital admission with having a congenital choledochal cyst with a bile duct tumor, although no pancreaticobiliary maljunction was detected. We resected the bile duct with the choledochal cyst and undertook Roux-en-Y reconstruction. The bile duct formed a diverticulum 6cm at the greatest dimension from the hepatic duct, and fibrosis and inflammatory cell invasion were found histologically. The tumor was found to be papillary carcinoma limited to mucosa without lymph node metastasis. Such type II choledochal cyst with early bile duct carcinoma is extremely rare. Exposure to pancreatic juice is thought to be a cause of bile duct cancer, but this was hard to conclude in this case.
