Which is the most common infiltrating neoplasm of the inferior vena cava?

• A. Renal cell carcinoma
• B. Hepatocellular carcinoma
• C. Leiomyosarcoma
• D. Lymphoma

Answer: (A)

Renal cell carcinoma is most likely to invade the inferior vena cava because it characteristically extends from the renal vein into the IVC as a contiguous tumor thrombus. This intravascular extension is a classic pattern for RCC and has important implications for imaging and treatment. On imaging, you’d expect a renal mass with a continuous intraluminal, enhancing filling defect that tracks up the renal vein into the IVC and may even reach higher into the hepatic IVC or toward the right atrium.

Hepatocellular carcinoma can involve the hepatic veins and may invade vascular channels, but it is not as commonly the source of direct IVC infiltration as RCC. Leiomyosarcoma originates in the wall of the IVC itself, making it a primary IVC tumor rather than a tumor that infiltrates the IVC from another site. Lymphoma can involve the area around the IVC via lymphadenopathy, but it is not the most common infiltrating neoplasm of the IVC.