PURPOSE: Small renal tumors are frequently detected during the screening of 
patients with a hereditary type of renal cancer. The development of nonsurgical 
treatment modalities would greatly improve quality of life in these patients. We 
present our experience with radio frequency interstitial tissue ablation, a 
heating device approved by the Food and Drug Administration for treating soft 
tissue tumors.
MATERIALS AND METHODS: Patients underwent radio frequency interstitial tissue 
ablation of small renal tumors just before surgical excision. Pathological 
examination of the renal tumors was done to evaluate the treatment effect. 
Computerized tomography and renal function testing were performed before and 
after therapy to evaluate toxicity.
RESULTS: Four patients underwent treatment of a total of 14 tumors with the 
radio frequency interstitial tissue ablation device just before surgical removal 
of the tumors. All lesions were brown after ablation, in contrast to the normal 
pink appearance of untreated lesions that were resected. On color Doppler 
ultrasound blood flow to each tumor evident before was not visualized after 
treatment. The Wilcoxon rank sum test demonstrated no difference preoperatively 
and postoperatively in blood urea nitrogen, serum creatinine, creatinine 
clearance or differential renal function. We identified no toxicity associated 
with radio frequency interstitial tissue ablation. Of the excised tumors 11 were 
renal cell carcinoma and 3 fibrotic hemorrhagic cysts. For renal cell carcinoma 
the treatment effect involved the loss of nuclear detail and nonvisualization of 
nucleoli. These changes were not observed in any tumors resected without radio 
frequency interstitial tissue ablation. The treatment effect was noted in 10 of 
the 11 lesions, and in 1 case the treatment effect involved 35% of the tumor.
CONCLUSIONS: No toxicity was associated with radio frequency interstitial tissue 
ablation. Percutaneous treatment of renal tumors is planned to evaluate the 
treatment effect better and further evaluate toxicity.