A report of 5 cases of cystic bile duct carcinoma of the liver and proposal of a new classification.

Primary biliary cystadenocarcinoma of the liver is rare. Among 239 patients with primary liver cancer admitted to our service during the last 13 years, there were 5 cases of cystic bile duct carcinoma of the liver. Three of these were cystadenocarcinoma, one was adenocarcinoma arising from a liver cyst, and one was carcinoma of the intrahepatic bile ducts with cystic dilatation. A better classification of these entities seems necessary, and it is suggested that malignant cystic tumors of the liver should be divided into 3 groups: Group A is cystic adenocarcinoma, group B is bile duct carcinoma with primary or secondary intrahepatic bile duct, and group C is degenerative cyst formation by other types of malignant tumors. Cystic adenocarcinoma (Group A) can then be further subdivided into cystadenocarcinoma, cystadenocarcinoma with cystadenoma, and carcinoma in a simple cyst of the liver.