Liver metastasis with intraductal invasion originating from rectal cancer: report of a case.

We report a case of liver metastasis with intraductal invasion from colorectal cancer. The patient underwent abdominoperineal resection of the rectum for rectal cancer, and a computed tomography (CT) scan, done 4 years later, revealed a low-density lobular mass in the left lobe of the liver, with a tumor embolus in the second branch of the left bile duct (B2). Because the preoperative imaging findings showed an intraductal growth pattern, we performed a left lobectomy of the liver for intrahepatic cholangiocarcinoma (IHCC). Immunohistochemically, the carcinoma cells, including the intraductal growth, were focally positive for Cytokeratin (CK) 20, but negative for CK 7. This CK staining pattern suggested that the liver tumor was a metastasis from the previously resected rectal cancer. Thus, metastases from colorectal cancer can involve intraductal growth.