Renal cell carcinoma in an end-stage kidney: Evaluation with spectral Doppler ultrasound

The major reason for clinical concern in end-stage renal disease (ESRD) is the increased incidence of renal cell carcinoma (RCC). Ultrasound (US) has been the imaging procedure of choice in patients with impaired renal function. However, the small kidneys of ESRD are often difficult to image with US. We present spectral Doppler US findings in a case of RCC associated with ESRD and suggest the use of spectral Doppler US in the detection and differential diagnosis of RCC associated with ESRD. In our case, the Doppler US spectrum in the RCC showed high peak systolic velocity and low resistance, which was quite different from the high-resistance spectrum in other parts of the kidney. High peak systolic velocity in renal malignancies is probably due to intratumoral arteriovenous shunting. Abnormal blood vessels formed by an angiogenic factor secreted in malignant lesions lack the normal requisite of smooth muscle cells within their walls. Consequently, resistance to flow is decreased and diastolic flow is increased, resulting in a low-resistance flow pattern. Hence, spectral Doppler US can be used in the evaluation of kidneys with ESRD, especially when RCC is suspected.