Abstract
Metastatic colorectal cancer is relatively rare. Herein, we report a case of metastasis to the rectum from primary transverse colon cancer. The patient was a 65-year-old man who underwent curative partial colectomy due to transverse colon cancer. The pathological findings of the resected specimen were well-differentiated tubular adenocarcinoma with regional lymph node metastasis. An increase in his carcinoembryonic antigen (CEA) level was observed during the follow-up of 2 years 7 months after the primary surgery. Positron emission tomography revealed a solitary tumor in the submucosal layer of the rectum, though a biopsy could not prove that it was a metastatic tumor. A laparoscopic low anterior resection was performed for this tumor. The pathological findings revealed that the tumor was a tubular adenocarcinoma similar to the primary transverse colon cancer, which existed in the submucosal, muscular, and subserosal layers. We therefore considered it to be metastatic cancer to the rectum, even though the metastatic route was unclear. Although metastatic colorectal cancer is rare, physicians should keep it in mind as a potential diagnosis.
