Laparoscopic Radiofrequency Ablation Combined with Surgical Excision for Exophytic Renal Angiomyolipoma: A Novel Technique Based on Tumor Vasculature Features of Enhancing Renal Masses Toward Hilar Off-Clamping Nephron-Sparing Surgery

Objectives: Symptomatic angiomyolipoma (AML) and asymptomatic AML larger than 4 cm in size are usually treated with nephron-sparing surgery or transarterial embolization. We used radiofrequency ablation to treat the vascular pedicle of exophytic AML with low R.E.N.A.L. nephrometry score and investigated its feasibility for hilar off-clamping nephron-sparing surgery. Methods: Contrast-enhanced computed tomography (CT) showed enhanced, well-defined lipomatous tumors with a maximum diameter of 4-8 cm in the kidney of 15 patients. Results indicated that the exophytic tumors featured in the enlarged tumor vasculatures extended into the parenchyma of the involved kidney. The patients underwent radiofrequency ablation by using a Cool-tip (TM) probe placed into the root of the AML mass from different directions under laparoscopic ultrasonography guidance. After sealing the vascular pedicle of the tumor, the bloodless tumors were resected en bloc without renal hilar clamping or suturing the resection defect of the kidney. Results: All patients underwent the procedure smoothly, and no perioperative complications occurred. The contrast-enhanced CT scan showed small defects in the contrast-enhanced renal parenchyma at third month after the procedure, and the decrease in function of the treated kidneys was <10% during the 12-month follow-up. Conclusions: Our initial experience suggests that sealing the tumor vessels by radiofrequency ablation based on the tumor vasculature features of a renal mass is an alternative to hilar clamping in laparoscopic nephron-sparing surgery. Laparoscopic radiofrequency ablation and tumor excision are a definitive and safe minimally invasive procedure that allows the successful removal of exophytic sporadic AML mass with low R.E.N.A.L. nephrometry score.