A reappraisal of sonolucent renal masses.

The authors present a differential diagnosis of echo-free renal masses and emphasize that such lesions are not always simple cysts. Of 312 renal sonograms, 15 showed sonolucent masses which proved to be something other than a simple cyst. Pathological diagnoses included abscess, hematoma, renal artery aneurysm, hydronephrosis, and homogeneous or cystic tumor. To achieve optimal diagnostic accuracy, it is insufficient to rely solely on sonolucency as demonstrated on the sonogram. Any disparities in the radiological, clinical, or ultrasonic findings demand further evaluation. Nephrotomography, angiography, aspiration biopsy, or exploration should be selected in a sequence which is appropriate to ensure correct diagnosis while minimizing the risk to the patient.