A case report of a long-surviving patient with mediastinal lymph node carcinoma from an unknown primary site, with a review of 31 cases reported in Japan

Abstract

A 53-year-old man with a complaint of dyspnea on effort was referred to our hospital. Chest x-ray demonstrated a tumor located in the subaortic region. Mediastinal lymph node metastasis was suspected, though no primary lesion was detected. Resection of an enlarged mediastinal lymph node was therefore performed to confirm the diagnosis. Histological examination revealed that the lymph node consisted of poorly differentiated adenocarcinoma with immunoreactivity for keratin and EMA as epithelial markers. No recurrence has been noted for 6 years, without additional treatment. We often treat patients with metastatic cancer from an unknown primary lesion, many of whom suffer relapse and have a poor outcome. We therefore report this rare case of a long-surviving patient with mediastinal lymph node carcinoma from an unknown primary lesion. A review of 31 previously reported cases in Japan revealed that patients with mediastinal lymph node carcinoma from an unknown primary lesion have a better prognosis than those with N2 lung cancer, and exhibit prolonged survival with aggressive medical treatment. We therefore propose that patients with mediastinal lymph node carcinoma from an unknown primary lesion should be treated aggressively.