Metastatic Thymic Adenocarcinoma from Colorectal Cancer

This report describes the case of a 57-year-old man with an anterior mediastinal tumor. Four years previously, he underwent laparoscopic anterior resection for sigmoid colon cancer. Thirty months after that procedure, bilateral pulmonary metastasectomy was performed. Twelve months later, follow-up computed tomography revealed a 1-cm pulmonary nodule on the upper lobe of the right lung and a solid mass on the anterior mediastinum, and the patient was also observed to have an elevated serum carcinoembryonic antigen (CEA) level. Repeated pulmonary nodule resection and total thymectomy were performed. Immunohistochemical staining of the anterior mediastinal tumor revealed adenocarcinoma, and his serum CEA level returned to normal after the operation. These findings strongly suggested metastatic thymic adenocarcinoma from a colorectal cancer.