Clinical and radiographic trends in patients with renal angiomyolipomas (AML).

Abstract

458 Background: Renal angiomyolipoma (AML) is a common benign solid tumor of the kidney, typically found incidentally through imaging. These tumors can also present with symptoms like flank pain, hematuria, or retroperitoneal bleeding. AMLs are usually monitored and treated when they reach sizes between 4 and 6 cm based on clinical judgment, although the timing for intervention remains debated. This study aimed to investigate growth rates, assess radiographic features, and evaluate trends in clinical presentation. Methods: This multicenter, single-institution retrospective study reviewed patients diagnosed with renal AML at three Mayo Clinic locations (Rochester, Arizona, Jacksonville) from 1997 to 2021. Eligible patients had at least three abdominal scans over a minimum of two years and 36 months of follow-up. We reviewed radiologic reports, images, and charts to record demographics, tumor characteristics, imaging modalities, intervention rates, tumor sizes, and growth rates. The Mann-Whitney and Fisher exact tests were used for comparisons. Results: Among 839 patients, most were female (81.6%), with a median age of 58.55 years. Bleeding patients had significantly larger initial tumors (median 6.50 cm) compared to non-bleeding patients (median 1.20 cm), p < 0.001. Treatment with everolimus was more common in bleeding patients (12.2% vs. 2.1%), and the prevalence of tuberous sclerosis was higher in the bleeding group (19.5% vs. 6.3%). All bleeding patients underwent intervention, while 22.3% of the overall cohort received treatment. Follow-up duration and total scans did not differ significantly between groups. Over 12 months, non-bleeding patients had a median growth change of 0.00 cm [IQR: 0.00, 0.30], whereas bleeding patients showed a median growth change of 0.40 cm [IQR: 0.15, 1.00], p = 0.002. Conclusions: This study reveals significant differences in characteristics and growth patterns of renal angiomyolipomas between bleeding and non-bleeding patients. Bleeding patients had larger initial tumors and greater growth changes over time. Further studies on radiographic features may help identify lesions needing earlier intervention. Demographic and clinical characteristics of patients with renal AML: Comparison bleeding vs non-bleeding groups. Overall Non-bleeding Bleeding P-Value N 839 798 41 Gender (%) Female 685 (81.6) 650 (81.5) 35 (85.4) 0.793 Male 152 (18.1) 146 (18.3) 6 (14.6) Unknown 2 (0.2) 2 (0.3) 0 (0.0) Age (median [IQR]) 58.55 [47.04, 66.95] 58.72 [47.32, 67.19] 53.84 [42.88, 60.82] 0.015 Follow up (months) (median [IQR]) 45.30 [37.12, 89.15] 46.45 [36.32, 89.52] 39.70 [36.30, 61.63] 0.233 Total scans (median [IQR]) 3.00 [3.00, 5.00] 4.00 [3.00, 5.00] 3.00 [3.00, 4.00] 0.282 Initial size (cm) (median [IQR]) 1.30 [0.80, 2.70] 1.20 [0.70, 2.50] 6.50 [3.00, 9.30] <0.001 Everolimus (%) Yes 22 (2.6) 17 (2.1) 5 (12.2) 0.001 Tuberous sclerosis (%) Yes 58 (6.9) 50 (6.3) 8 (19.5) 0.003 Intervention (%) Yes 187 (22.3) 147 (18.4) 41 (100) <0.001