Macroscopic classification and preoperative diagnosis of intrahepatic cholangiocarcinoma in Japan

We reviewed the records of 64 patients with resected intrahepatic cholangiocarcinoma (ICC) according to the macroscopic classification proposed by the Liver Cancer Study Group of Japan, in which ICC is classified into three types based on the macroscopic appearance of the cut sur-face of the tumor: mass-forming, periductal-infiltrating, and intraductal growth types. There were 24 patients with the periductal-infiltrating type, 28 with the mass-forming type, and 12 with the intraductal growth type. The mass-forming type essentially showed expansive growth irrespective of hilar invasion. The periductal-infiltrating type of tumor exhibited diffuse infiltration along the portal pedicle, and preoperative planning of the resection procedure was similar to that for primary bile duct carcinoma of the hepatic confluence. Vascular resection and reconstruction was required in some patients with advanced disease. In the intraductal growth type of tumor, precise determination of tumor extent was difficult because of the ambiguity caused by abundant mucin secreted by the tumor and/or by the superficial mucosal spread of the tumor along the bile duct. Percutaneous transhepatic cholangioscopy provided the most reliable information for designing the operative procedure. The macroscopic classification is useful for preoperative diagnosis of tumor extent and for planning the surgical procedure.