Oncocytoma on Renal Mass Biopsy: Is It Still the Same Histology When Surgery Is Performed? Results from UroCCR-104 Study - Beyond the Abstract

In the case of a diagnosis of renal oncocytoma (RO) on renal mass biopsy (RMB), patients could be offered either active surveillance (AS) or active treatment.1 On the one hand, more and more series showed that AS is a safe strategy.2 On the other hand, the reliability of a diagnosis of RO on RMB is often questioned, because of a risk of hybrid oncocytic/chromophobe tumor (HOCT). This unresolved question is manifested by various strategies among urologists in a situation of suspected RO on RMB.3

Despite the broadcasting of RMB among centers and improvement in the characterization of RMB for oncocytic tumors, to the best of our knowledge, no studies re-examined the correlation between suspected RO on RMB and definitive histology since the meta-analysis from Patel et al in 2017 (which was based on very small cohorts: maximum 13 patients by cohort, 48 patients overall).5

We performed a retrospective study conducted in the framework of the UroCCR project which is a French multi-institutional prospectively-maintained database of patients treated for kidney tumors.  All tumors with oncocytoma on RMB were selected and all pathological reports were reviewed. Patients with the RMB simultaneously performed with a focal treatment, synchronous bilateral tumors, and ambiguous RMB reports were excluded.

Overall, 119 tumors with oncocytoma on RMB, from 15 centers, were included. On final pathology, only 51 of the 75 surgically treated tumors (68.0%) had oncocytoma, while 24 presented malignant tumors (mainly chromophobe carcinoma (19.2%), and hybrid oncocytic chromophobe tumors (HOCT) (6.8%)) leading to a discrepancy of 32.0% between RMB and final pathology. The only predictive factor of a discrepancy between RMB and definitive histology was a biopsy done outside of the center (Odds ratio: 3.22 [95%-confidence interval: 1.08-9.61], p=0.03). Age, tumor size, sex, or upfront surgery were not predictive factors of discrepancy.

Several explanations could be proposed to explain the discrepancy: first, affirming a diagnosis of RO on small samples of RMB can be challenging and need expertise, second, this surgical cohort may be associated with a selection bias, third, because of tumor’s heterogeneity in HOCT, RMB could not catch the fundamental characteristics of the tumor.

This study shouldn’t be interpreted as advocacy to reject RMB strategy in the management of renal masses. Despite these results, several arguments advocate in favor of AS strategy concerning RO on RMB. Indeed, in small renal masses. AS has been proven to be a safe option in biopsy proven malignant tumors.5 Moreover, chromophobe carcinomas have a low aggressive profile and small probability to develop metastasis in the majority of the cases, especially if they don’t harbor sarcomatoid features. Only 3 patients in our study had non-oncocytic tumors.

Several limitations of our study should be acknowledged: no centralized pathological review of the RMB, number of patients rather small (but comparable or even higher than previous studies), potential selection bias induced by a surgical cohort, disparity in the correlation between RMB and final histology observed between centers.

We believe that in the light of this study, honest but not too much alarmist information should be given to patients, namely that a malignant tumor cannot be strictly ruled out by a result of RO on RMB, but AS remains a safe option. Treatment strategy should be then decided considering multiple cofactors (such as patient age, comorbidities, anxiety, tumor size and growth) to assess the benefit/risk ratio, in a shared-decision making process. Besides, if AS is chosen, the window of the possibility of conservative treatment options (partial nephrectomy, focal treatments) should not be missed during follow up if tumor size is increasing.

Written by: Nicolas Branger, Department of Urology, Institut Paoli Calmettes Cancer Center, Marseille, France


  1. Bedke J, Albiges L, Capitanio U, Giles RH, Hora M, Lam TB, et al. Updated European Association of Urology Guidelines on Renal Cell Carcinoma: Nivolumab plus Cabozantinib Joins Immune Checkpoint Inhibition Combination Therapies for Treatment-naïve Metastatic Clear-Cell Renal Cell Carcinoma. Eur Urol. march 2021;79(3):339‑42
  2. Neves JB, Varley R, Agnesi S, Withington J, Rodrigues FB, Warren H, et al. Growth and renal function dynamics of renal oncocytomas in patients on active surveillance. BJU Int. dec 2021;128(6):722‑7.
  3. Warren H, Neves JB, Tran MGB. Renal oncocytoma: landscape of diagnosis and management. BJU Int. Dec 2021;128(6):685‑7
  4. Patel HD, Druskin SC, Rowe SP, Pierorazio PM, Gorin MA, Allaf ME. Surgical histopathology for suspected oncocytoma on renal mass biopsy: a systematic review and meta-analysis. BJU Int. May 2017;119(5):661‑6.
  5. Mir MC, Capitanio U, Bertolo R, Ouzaid I, Salagierski M, Kriegmair M, et al. Role of Active Surveillance for Localized Small Renal Masses. Eur Urol Oncol. 1st august 2018;1(3):177‑87.
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