Renal Spindle Cell Tumor with Thrombus Extension into the Inferior Vena Cava and the Right Atrium Depicted by PET/CT Scan.

Tumor thrombus (also called intravascular tumor extension) can be defined as tumor extending into vessel; typically a vein, it occurs in a lot of malignancies like hepatocellular carcinoma, Wilms tumor, and others. 1 Tumor thrombus has been reported to demonstrate increase in fluorine-18 fluorodeoxyglucose (FDG) uptake that would differentiate it from the benign bland thrombus which would not take up FDG on positron emission tomography/computed tomography (PET/CT) scan. 1 We present a case of spindle cell sarcoma of right kidney whose baseline contrast-enhanced CT revealed a mass replacing the right kidney and right renal vein associated with thrombus in the inferior vena cava (IVC). F-FDG PET/CT imaging was done that revealed an FDG-avid hypermetabolic malignant right renal mass with hypermetabolic IVC thrombus extending to the right atrium.