Solitary metastasis to a superior mediastinal lymph node after distal gastrectomy for gastric cancer: a case report

BACKGROUND: Mediastinal lymph node metastases occasionally occur in patients of advanced gastric cancer of the cardia with esophageal invasion, but they rarely occur in patients with gastric cancer of other sites. This report describes a case of a solitary metastasis to t a superior mediastinal lymph node after distal gastrectomy for gastric cancer of the antrum. CASE PRESENTATION: A 70-year-old man underwent curative distal gastrectomy for advanced gastric cancer of the antrum (pT2pN2M0, stage IIB). Postoperatively, he underwent adjuvant chemotherapy with S-1 (100 mg/day). Although the serum levels of his tumor markers increased after surgery, computed tomography scans did not detect evidence of early recurrence in the superior mediastinum. However, a (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) scan showed accumulation of fluorodeoxyglucose in the upper mediastinum with no evidence of recurrence elsewhere. Therefore, a solitary superior mediastinal lymph node was suspected to have a metastatic lesion derived from the gastric cancer. The patient underwent tumor resection right mini-thoracotomy two years and three months following gastrectomy. A pathological examination demonstrated moderately differentiated adenocarcinoma, confirming that it was a metastatic adenocarcinoma from the gastric cancer. The patient developed recurrences in the superior mediastinum and several right costa six months following the second surgery. He was treated with chemotherapy, but he died 18 months after the second operation. CONCLUSION: We present a rare case of a solitary metastasis to a superior mediastinal lymph node after distal gastrectomy for gastric cancer. An FDG-PET scan is useful for the diagnosis of mediastinal lymph node metastasis in gastric cancer. Metastasis to the superior mediastinal lymph nodes from gastric cancer in sites other than the cardia suggests systemic expansion of gastric cancer, and therefore, even a solitary metastasis may be related to a poor prognosis.