Abstract:

Objective: Giant renal angiomyolipoma (RAML), typically defined as having a maximum diameter of ≥8 cm, presents formidable surgical challenges and heightened clinical risks. These challenges primarily stem from the tumor's extensive volume, highly enriched but fragile vascularization, and significant susceptibility to spontaneous rupture and life-threatening hemorrhage. This study aims to comprehensively evaluate the clinical effectiveness and safety of laparoscopic nephron-sparing surgery (NSS) for the management of these complex giant lesions. Methods: A retrospective analysis was performed on 45 patients with giant (≥8 cm) RAML who received NSS at Peking University Third Hospital between January 2012 and September 2025. The cohort comprised 11 males and 34 females with a mean age of (40.9±14.1) years and a mean body mass index (BMI) of (23.7±4.0) kg/m². Preoperatively, 5 patients had a history of spontaneous hemorrhage, and 2 were pregnant. The mean maximum tumor diameter was (10.3±2.2) cm, ranging from 8.0 to 15.4 cm. Surgical procedures included standard laparoscopy (39 cases) and Da Vinci robotic-assisted laparoscopy (6 cases), utilizing either a retro-peritoneal approach (32 cases, 71.1%) or a transperitoneal approach (13 cases, 28.9%). Pathological diagnosis and differentiation were conducted in strict accordance with the 2022 World Health Organization (WHO) classification of tumors. Key outcome measures included operative time, warm ischemia time, estimated blood loss, postoperative complications, and length of postoperative hospital stay. Results: All the 45 operations were successfully completed with complete tumor resection and nephron preservation, although 5 cases required conversion to open surgery due to severe adhesions or bleeding. The operative time was (180.6±55.7) min (range: 86-312 min), the warm ischemia time was (21.9±9.8) min (range: 6-40 min); 36 cases had a warm ischemia time ≤30 min, while a zero-ischemia technique was employed in 3 cases. The postoperative hospital stay was (6.2±2.6) days (range: 3-14 days), and the time to drainage tube removal was (5.1±2.2) days (range: 2-14 days). Postoperative patho-logy confirmed RAML in all cases, and all surgical margins were negative. Postoperative complications included one case of pulmonary infection and one case of renal insufficiency. During a follow-up of 3 to 43 months, no tumor recurrence or significant loss of renal function was documented. Conclusion: NSS for selected patients with giant RAML is effective in preserving renal function while ensuring complete tumor resection, negative margins, and avoiding short-term and long-term complications. Robotic-assisted systems, in particular, offer distinct advantages in complex wound reconstruction and the reduction of surgical complications.

Key words: Renal angiomyolipoma, Nephron-sparing surgery, Laparoscopy, Treatment outcome