Renal Vein and Inferior Vena Cava Tumor Thrombus: Presentation and Mapping of Venous Extension with Color Duplex Ultrasound

Abstract

Introduction Renal cell carcinoma (RCC) has a unique tendency toward intravascular growth into the renal vein (RV), inferior vena cava (IVC), or even into the heart. To determine the operative approach and degree of surgical resection required, an accurate preoperative assessment of the extent of the tumor thrombus (TT) is mandatory. The purpose of this report is to describe the presentation of TT with color duplex ultrasound (CDU) and to report our initial experience in mapping the extent of vascular invasion in five patients. Methods Between January and November 2004, 5 patients with suspected RCC underwent a renal CDU examination. The presence and extent of TT by CDU was correlated with contrast enhanced computerized tomography (CT), magnetic resonance imaging (MRI) or surgical findings. Results Three men and two women were found to have a unilateral renal mass. The arterial supply to each tumor was conspicuous and consisted of prominent feeding arteries by color or power Doppler that circumscribed and penetrated the mass. TT was localized to the RV in one case and involved the RV and IVC in four. For two patients, the growth of TT into the IVC was limited and nonocclusive whereas in two others it was extensive and occlusive. In one case, TT invaded the IVC and the contralateral RV. By gray-scale imaging, TT appeared as an echogenic, heterogeneous mass that caused focal dilatation of the vein followed by rapid tapering. Interestingly, in three patients, low-resistance pulsatile flow could be recorded within the TT tissue itself. When compared with computed tomography, magnetic resonance imaging, or the operative findings, CDU agreed with the location and extent of TT in all 5 cases. Conclusion CDU appears to be an accurate technique for mapping the extent of TT in patients with RCC. Although this series is small, the unique gray scale and spectral Doppler characteristics of TT noted on CDU may be beneficial in distinguishing bland thrombus from TT.