Incidence of Benign Renal Masses in a Contemporary Cohort of Patients Receiving Partial Nephrectomy for Presumed Renal Cell Carcinoma - Beyond the Abstract

The incidence of small renal masses (SRM) has continued to rise over the past several decades secondary to the increased utilization of cross-sectional imaging for unrelated reasons.

The management of SRMs has primarily revolved around extirpative surgery (1st with radical nephrectomy and eventually with nephron sparing surgery), however, studies found a relatively high rate of benign pathology (ranging from 15-30%)1,2 and no associated improvement in cancer specific survival due to the indolent nature of malignant small renal masses.3 These findings have encouraged the increased utilization of active surveillance (AS) protocols and the increased utilization of pre-operative diagnostic tools including MRI and 99mTc-Sestamibi and renal mass biopsy (RMB) to enhance patient selection for surgical treatment. Though these changes have been progressively implemented over the past decade, it remains unclear if this has led to a decrease in the rate of benign pathology in contemporary practice.

In this study, we examined a cohort of 1229 patients from a prospectively maintained IRB approved database of patients undergoing PN for SRM with presumed RCC between 2006-2021. We examined pre-operative patient and tumor characteristics as well as the incidence of benign pathology over time. We found that the overall incidence of benign pathology at our institution did not decrease over time, with the predominant histology subtype being oncocytoma. Interestingly, we also noted that the incidence of angiomyolipoma (AML) decreased over time, while the incidence of oncocytoma increased over time.

Our findings highlight that the incidence of benign pathology in patients undergoing surgery for presumed RCC remains high at 19.2% despite attempts to improve contemporary practice with AS protocols, utilization of advanced imaging modalities, and RMB. Our findings also highlighted an increasing trend in the incidence of oncocytoma in relation to AML, suggesting that oncocytoma specifically continues to pose a pre-operative diagnostic challenge in the management of SRMs.

Our study is limited in that it does not capture patients who remained on AS and never underwent surgery, or patients who were found to have benign pathology on RMB and were excluded from surgery. Despite this, we feel that our findings are reflective of contemporary high volume surgical centers and highlight that there is still significant room for improvement in patient selection in the management of SRM. We hope this study prompts further investigations into the development of novel biomarkers (liquid and tissue-based) and imaging techniques (radionics, artificial intelligence algorithms) to aid in the detection of benign tumors prior to extirpative surgery.

Written by: Varun Vijay, Fjolla Hyseni Vokshi, Michael Smigelski, Shavy Nagpal, William C. Huang

NYU Langone Health, New York, NY., NYU Langone Health, New York, NY.


  1. Kutikov Alexander, et al. Incidence of benign pathologic findings at partial nephrectomy for solitary renal mass presumed to be renal cell carcinoma on preoperative imaging. Urology . 2006;68:737–740.
  2. Kim Jae Heon, et al. Association of prevalence of benign pathologic findings after partial nephrectomy with preoperative imaging patterns in the United States from 2007 to 2014. JAMA Surg . 2019;154:225–231.
  3. Znaor Ariana, et al. International variations and trends in renal cell carcinoma incidence and mortality. Eur Urol. 2015;67:519–530.
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