Ultrasound showing left renal tumor. A: Ultrasound revealed hypoechoic masses (arrow) with ill-defined border in the central region around renal sinus. B: Color doppler flow imaging of mass (arrow) indicated decreased blood flow signals. The tumor invaded renal pelvis inward and infiltrated vessel pedicle outward, and caused caliectasis. AO: abdominal aorta; LRA: left renal artery.