CT DIAGNOSIS OF TUMOR THROMBUS OF THE RENAL VEIN AND INFERIOR VENA CAVA

Abstract

It is not infrequent that renal tumor produces tumor thrombus by infiltrating the inferior vena cava through the renal vein. Conventionally, tumor thrombus of the renal vein or inferior vena cava were diagnosed by use of renal arteriography, inferior venacavography and ultrasonography. We used computed tomography (CT) for diagnosis in 4 cases of renal tumor associated with tumor thrombus of the renal vein and inferior vana cava. The results obtained are described below:
A total of 4 cases consisting of 3 cases of renal cell carcinoma and one case of squamous cell carcinoma of the renal pelvis, treated at the Jikei University Hospital during the six months period from January to June of 1979, were studied. The affected side was right in 3 cases and left in one case. In all of the former cases the tumor thrombus was extending from the renal vein to the inferior vena cava, while in the latter case it was confined in the renal vein. All these 4 cases received CT together with renal arteriography and inferior venacavography, followed by nephrectomy, and were confirmed of the presence of tumor thrombus in the renal vein and inferior vena cava operatively.
CT findings revealed a pronounced enlargement of the renal vein, and tumor thrombus of the renal vein was diagnosed in all of the 4 cases. In 2 of 3 cases in which tumor thrombus extended to the inferior vena cava, the dilated renal vein was found to be connected to the slightly dilated inferior vena cava, while in the remaining one case the outline of the inferior vena cava was obscure, showing no clear dilatation. After contrast enhancement, a filling defect was seen in the inferior vena cava. CT findings of tumor thrombus in the vein indicated a dilatation of the renal vein and inferior vena cava. In addition, a filling defect was found after contrast enhancement, suggesting that CT is helpful as a diagnostic aid.
From these results it is considered that CT is valuable and to be used together with renal arteriography, inferior venacavography and ultrasonography, and appears to be especially useful for cases in which striated vascular pattern is not depicted by renal arteriography and in which it is not clear whether the filling defect by inferior venacavography is due to tumor thrombus or to the pressure from the tumor.