Tumor-to-tumor metastasis: report of an autopsy case of lung adenocarcinoma metastasizing to renal cell carcinoma.

Metastasis of one tumor to another tumor within the same individual is considered rare. Lung cancer metastatic to renal cell carcinoma represents the most common combination of such tumor-to-tumor metastases. We present the autopsy case of a 97-year-old woman with metastatic adenocarcinoma of the lung to renal cell carcinoma.