Abstract
Background. Metastatic thoracic lymph node carcinoma of unknown origin is a rare disorder and many aspects of the disease are unknown. We present here a case that showed a good response to bevacizumab and pemetrexed chemotherapy for lung cancer. Case. A 40-year-old man was admitted for evaluation of an abnormal shadow on his chest radiograph, which was incidentally pointed out at a health checkup. Chest computed tomography showed multiple enlarged lymph nodes mainly in the mediastinum. The biopsied specimen of the right supraclavicular lymph node was confirmed as poorly differentiated adenocarcinoma. Immunohistochemistry revealed the neoplastic lesion to be positive for napsin A, positive for cytokeratin (CK) 7, negative for CK 20, and negative for thyroid transcription factor-1. Although whole body examination failed to detect the primary site of the adenocarcinoma, the results of the immunohistochemistry strongly suggests the metastatic carcinoma to be lung origin. He was treated with carboplatin/paclitaxel/bevacizumab, and after 3 courses the tumor regressed markedly and partial remission was achieved. Thereafter, bevacizumab was continued for maintenance therapy, but a small brain metastasis appeared. Following gamma-knife therapy, he underwent 5 courses of cisplatin/pemetrexed chemotherapy. He has remained symptom free for 16 months without recurrence. Repeated searches have failed to identify the site of the primary lesion. Conclusion. There are 102 reported cases of metastatic thoracic lymph node carcinoma of unknown origin in Japan. Most cases involve male smokers, right-side predominance, and very good outcome. Diagnosis was lung cancer immunohistochemically in 12 of these cases and primary lung lesions were apparent in 10 other cases. Therefore, it is highly plausible that the cause of metastatic thoracic lymph node cancer of unknown origin could be T0 lung cancer.
