Unusual metastatic sites from renal cell carcinoma detected by 18F-FDG PET/CT scan.

Here we describe 2 cases of renal cell carcinoma where we found the unusual metastatic sites from renal cell carcinoma on 18F-FDG PET/CT scans in post-radical nephrectomy status. The first case resolves the venous migration of the tumor as a malignant thrombus arising from a remnant stump of the left renal vein, passing through hemiazygos vein further into the azygos vein and finally into the superior vena cava just before entering into the right atrium. The second case demonstrated extensive skeletal muscle deposits involving the muscles of the trunk as well as upper and lower extremities.