Solitary anterior mediastinal lymph node metastasis with pericardial invasion from colon cancer: A case report

Colorectal cancer commonly metastasizes to the regional lymph nodes, liver, lungs and peritoneum. At present, mediastinal lymph node metastasis from colorectal cancer is uncommon and poorly understood. The present study reported a case of solitary anterior mediastinal lymph node metastasis with pericardial invasion from transverse colon cancer. An 82-year-old woman had a history of colectomy with regional lymph node dissection for transverse colon cancer (T1N1bM0 stage IIIA in the UICC classification). The patient had no symptoms, but follow-up contrast-enhanced computed tomography revealed an anterior mediastinal tumor compressing the heart 18 months after colectomy. The tumor showed fluorodeoxyglucose uptake on positron emission tomography. Resection of the anterior mediastinal tumor with pericardiectomy was performed. The tumor was 35x25 mm in size and was histopathologically characterized to be adenocarcinoma. These cells expressed cytokeratin (CK)20 and caudal-type homeobox protein 2 but not CK7 and thyroid transcription factor 1 on immunohistochemical analysis, confirming a diagnosis of metachronous mediastinal metastasis originating from colon cancer. The tumor cells invaded the adjacent pericardium and diaphragm pathologically. The patient has lived without recurrence 8 months after the surgery for mediastinal metastasis. In conclusion, clinicians should consider metastasis to the mediastinum during follow-up in patients with colorectal cancer. Surgery may be the most reliable treatment for solitary anterior mediastinal lymph node metastasis, preventing carcinomatous pericarditis through direct pericardial invasion.