Introduction: Renal angiomyolipoma (RAML) is a benign tumor composed of varying amounts of mature adipose tissue, smooth muscle and thick-walled blood vessels. RAML tend to grow over time requiring active intervention due to serious associated complications, such as hemorrhage and pain. Although RAML is an ideal tumor for organ preservation, data concerning efficacy of nephron-sparing surgery (NSS) are sparse. The aim of the study was to evaluate the efficacy of NSS in RAML with regard to renal function, tumor recurrence and surgical feasibility.
Patients and methods: Charts of patients with pathologically confirmed RAML were reviewed and data recorded: tumor size, associated symptoms, intraoperative blood loss, serum creatinine, follow-up data with regard to tumor recurrence and long-term renal function. A total of 28 patients were identified with RAML who underwent NSS because of tumor size > 4 cm, pain and/or to rule out malignancy due to radiographic features of uncertain interpretation.
Results: The median follow-up of all patients is 58 (3-114) months; median age was 55.6 (34-78) years, 24 patients were women, 4 patients were men. None of the patients developed a local recurrence. Median size of enucleated tumors was 5.5 (2.5-15) cm; indication for NSS was symptomatic tumor with hemorrhage in 4 patients (16%), prophylaxis of hemorrhage in 5 patients (20%) and radiographic features suspicious for malignancy in 16 patients (64%). In those cases, unenhanced and enhanced CT scans exhibit a hyperdense and a hypodense lesion as compared to the adjacent normal renal cortex, respectively. There were no intraoperative complications, median blood loss was 320 (50-1200) ml, none of the patients required blood transfusions. Post-operative course was uneventful in 26 patients (96%), 2 patients (7.1%) developed a urinary fistula managed by an endoluminal stent. Pre-operative serum creatinine was 0.9 (0.7-1.3) mg/dl, post-operative creatinine was 1.23 (0.7-1.5) mg/dl and serum creatinine at last follow-up was 0.95 (0.7-1.2) mg/dl.
Conclusions: NSS can be performed with a high success rate in RAML when surgical management is indicated. Long-term follow-up reveals no local tumor recurrences and stable renal function even in patients with a solitary kidney.