Metachronous mediastinal lymph node metastasis from ascending colon cancer: A case report and literature review

IntroductionMetachronous mediastinal lymph node metastasis without pulmonary metastasis is extremely rare in colorectal cancer, which makes the clinical diagnosis difficult and treatment strategy unclear.Prsentation of caseA case was a 59-year-old man, who had undergone right hemicolectomy for ascending colon cancer 2 years and 8 months previously, presented with enlarged mediastinal lymph nodes. ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography revealed FDG was accumulated only into the mediastinal lymph nodes. Serum carcinoembryonic antigen (CEA) level was within the normal range. Six months later, the size and FDG uptake of the mediastinal lymph nodes had increased. We assumed a possibility that the mediastinal lymph nodes were metastasized from ascending colon cancer and so performed thoracoscopic-assisted resection of the mediastinal lymph nodes. Histopathological analysis revealed the resected lymph nodes were filled with moderately differentiated adenocarcinoma and a diagnosis of mediastinal lymph nodes metastasis from previously-resected ascending colon cancer was made. The patient was postoperatively followed for more than 1 year and 8 months without any sign of recurrence.DiscussionOnly 7 cases of metachronous mediastinal lymph node metastasis from colorectal cancer, including our case, have been reported in the English literature. It is difficult to clinically diagnose mediastinal lymph node metastasis.ConclusionWe report a rare case of metachronous mediastinal lymph node metastasis from ascending colon cancer with literature review. If the mediastinal lymph nodes are enlarged after colorectal cancer resection, we need to make a treatment strategy as well as a diagnostic approach considering the possibility of mediastinal lymph node metastasis.