Radiofrequency Ablation of Large Renal Angiomyolipoma: Median-Term Follow-Up

To study the feasibility of percutaneous radiofrequency ablation (RFA) of large angiomyolipomas (AMLs) using saline-cooled electrodes.

Institutional Review Board approval for the study was received. Four patients (all female, age range 33–67 years) with large AMLs (maximal axis 6.1–32.4 cm) not suitable for embolotherapy or surgery consented to a trial of RFA. Procedures were performed under computerized tomographic guidance using 14G saline-infused electrodes. Two ablations (diameter 4–7 cm) were undertaken in each patient. Variables studied were technical success, treatment safety, alteration of tumor consistency, tumor size, effect on renal function, and medium-term freedom from haemorrhage.

All four patients underwent successful RFA without any intraprocedural complications. There has been no haemorrhage, or new renal specific symptom, during a minimum 48-month period, and normal renal function has been normal. On follow-up radiological imaging, the tumors have become fattier with involution of the soft-tissue elements (soft tissue–to–total tumor ratio decreased mean [range] of 0.26 [0.14–0.48] to 0.17 [0.04–0.34] U; p = 0.04 [paired Student t test]). Further evidence of treatment effect was the development of a capsule around the ablation zone, but there was no change in overall tumor volume (mean [range] 1,120 [118–2,845] to 1150 [90–3,013] ml; p = 1 [paired Student t test]).

RFA of large AMLs is technically feasible using saline-infused electrodes. The soft-tissue elements decreased in volume; the tumors become fattier; and there has been no renal haemorrhage during a 48-month period.