Intrabiliary polypoid growth of liver metastasis from colonic adenocarcinoma with minimal invasion of the liver parenchyma.

Liver metastases from colorectal cancer easily invade the Glisson's triad and sometimes have intrabiliary tumor growth. This behavior is by no means rare, and causes the cut end of the Glisson's triad to be positive for cancer. We report here a 72-year-old Japanese man with a medical history of ascending colon cancer in whom enhanced computed tomography (CT) showed a low-density mass in the caudate lobe of the liver and dilatation of the peripheral intrahepatic bile duct. He underwent right hemihepatectomy and caudate lobectomy. The resected specimen showed a polypoid tumor in the bile duct lumen, with minimal invasion of the liver parenchyma; the tumor was similar to cholangio-carcinoma. Histological findings proved it to be well-differentiated adenocarcinoma. Immunochemically, the tumor cells were positive for cytokeratin (CK) 20, but negative for CK7, and we finally diagnosed him with intrabiliary polypoid growth of liver metastasis from colonic cancer. For complete surgical resection, it is very important to diagnose intrabiliary tumor growth. However, we could not diagnose it preoperatively in spite of the CT detecting an intrabiliary polypoid tumor, because the CT revealed no extrabiliary tumors in the liver parenchyma. We have to pay attention to the fact that CT rarely demonstrates only intrabiliary growth without extrabiliary tumors.