Renal masses: value of duplex Doppler ultrasound in the differential diagnosis.

In a prospective study, 84 nonanechoic renal masses were examined with duplex Doppler ultrasound with a 3.5 mHz. transducer. This study included malignant lesions in 49 cases (30 renal carcinomas, 9 metastases, 8 lymphomas and 2 sarcomas) and benign lesions in 35 (18 complicated cysts, 6 inflammatory processes, 5 columns of Bertin, 3 angiomyolipomas and 3 hematomas). We analyzed whether duplex Doppler ultrasound can have a role in the differential diagnoses of these solid renal masses. Renal carcinomas demonstrated Doppler shifts of 2.5 kHz. or more in 23 cases (77%). These masses had significantly higher Doppler shifts than all of the other malignant masses (p < 0.001). Among the benign lesions the Doppler shifts were less than 2.5 kHz. in 33 cases (84%). The 2 masses with a Doppler shift of more than 2.5 kHz. in this group were inflammatory lesions. Detection of a Doppler shift of 2.5 or greater in a renal mass supports suspicion of a renal cell carcinoma, although an inflammatory process may also produce such a high Doppler shift. Doppler shifts of less than 2.5 kHz. in solid renal masses support the diagnoses of a benign lesion and a malignant lesion other than renal cell carcinoma.