Mediastinal and Hilar Lymph Node Metastases from Renal Cell Carcinoma with Concomitant Lung Carcinoma: A Rare Case with Unique Diagnostic Challenges

A 75-year-old man presented to our hospital 1 year after partial renal resection for clear cell carcinoma. A right lower lobe lung nodule noted at the time of surgery had increased to 3.0 cm in diameter and was confirmed as squamous cell lung carcinoma by bronchoscopic cytology. Computed tomography had also revealed paratracheal lymph node swelling. He underwent right lower lobectomy with lymph node dissection by video-assisted thoracic surgery. Pathological examination confirmed squamous cell carcinoma of the lung but diagnosed the right hilar and mediastinal lymph node metastases as clear cell carcinoma.