LAUSR

BackgroundLiver is a common location of colorectal metastasis, but intrabiliary growth of liver metastasis is not well recognized. Furthermore, intrabiliary metastasis that discovered over 10 years after excision has rarely been described.Case presentationAn 80-year-old man was admitted due to the presence of a liver mass in segment 5 (S5) concomitant with elevated carcinoembryonic antigen (CEA), and carbohydrate antigen (CA) 19–9. He underwent right hemicolectomy for colon cancer 12 years prior. Enhanced computed tomography (CT) showed dilated bile ducts with periductal enhancement in S5; hence, cholangiocarcinoma was suspected. Upon anterior segmentectomy, we observed that the cut surface of the specimen exhibited a yellowish-white tumor within the bile ducts. Histologically, the tumor formed within the papillary process, extended along the lumen, and replaced the normal bile duct epithelium. Immunohistochemical studies showed that the liver tumor and primary colon cancer were negative for cytokeratin (CK) 7 and positive for CK20 and Caudal-type homeobox transcription factor 2 (CDX-2). In addition, both tumors showed a same KRAS mutation. We diagnosed the liver tumor as liver metastasis recurrence from colon cancer.ConclusionIntrabiliary growth type of metastasis (IGM) is difficult to distinguish from cholangiocarcinoma, and sometimes develops long after surgery; thus, careful examination of a patient’s history is needed in such cases.