Contemporary surgical management of renal oncocytoma: a nation's outcome

Management strategies and oncological follow-up of a bicentric French cohort of biopsied renal oncocytomas

OBJECTIVE

Renal oncocytoma is a benign renal tumour whose management remains heterogeneous and poorly codified. The aim of this study was to describe the management strategies and evolution of a cohort of biopsied renal oncocytomas.

MATERIALS AND METHODS

We retrospectively reviewed renal oncocytomas biopsied in 2 French academic centres between 2009 and 2016. Demographic, anatomopathological, radiological and operative (if operated) variables were collected and compared between patients operated on and those monitored in order to identify those associated with the management strategy and clinical course.

RESULTS

Fifty-three patients were included with a mean follow-up of 29.6±32.3 months. Patients operated on immediately were younger (mean 57±11.5 years vs 68±9.8 years; P=0.007), less comorbid (Charlson 2.8 vs 4; P=0.01) with a higher RENAL score (9 vs 6; P<0.001) and a larger tumour size (mean 58±27 vs 27±13mm; P=0.002). Of the 28 patients monitored, 23 (82%) were still being monitored at the end of the study. The median duration of monitoring was 17.56 months. For the cohort as a whole, the mean tumour growth rate was 2.6mm/year (±2.5).

CONCLUSION

The management of oncytomas was heterogeneous. Tumour size, patient age and his comorbidities, RENAL score and tumour growth rate were the criteria associated with surgical treatment.

LEVEL OF EVIDENCE: 4

Renal mass biopsy - a practical and clinicopathologically relevant approach to diagnosis

Advancements in imaging modalities have increased the frequency of renal mass discovery. Imaging has typically been considered sufficient to guide management for a large proportion of these tumours, but renal mass biopsies (RMBs) have an increasing role in determining malignancy and can be a valuable tool for preventing unnecessary surgery in patients with benign tumours. A structured approach should be used to help to navigate the expanding repertoire of renal tumours, many of which are molecularly defined. In terms of tumour subtyping, the pathologist's strategy should focus on stratifying patients into clinically different prognostic groups according to our current knowledge of tumour behaviour, including benign, low-grade or indolent, intermediate malignant or highly aggressive. Crucial pathological features and morphological mimicry of tumours can alter the tumour's prognostic group. Thus, pathologists and urologists can use RMB to select patients with tumours at a reduced risk of progression, which can be safely managed with active surveillance within a tailored imaging schedule, versus tumours for which ablation or surgical intervention is indicated. RMB is also crucial in the oncological setting to distinguish between different high-grade tumours and guide tailored management strategies.

Identifying the facilitators and barriers to implementation of renal tumour biopsy in the diagnostic pathway for small renal masses

OBJECTIVES

To understand the facilitators and barriers to the implementation of renal tumour biopsy (RTB) in the diagnostic pathway for renal tumours in England.

PATIENTS AND METHODS

Participants consisted of patients who had a renal tumour diagnosed and/or treated at one of five tertiary centres in England, healthcare professionals involved in the direct care of patients diagnosed with renal tumours, and clinical service managers and commissioners. The study employed a mixed-methods research methodology consisting of individual interviews and an on-line survey that explored the types of facilitators and barriers individuals perceived and experienced and the frequency in which these were reported. A public dissemination event took place following the completion of data collection; to facilitate discussion of potential solutions to implementing RTB.

RESULTS

There were 50 participant interviews (23 patients, 22 clinicians, and five health service commissioners/operations managers). The patient on-line survey received 52 responses, and the clinician survey received 22 responses. Patients most frequently reported influences in choosing whether to undergo RTB pertained to wanting to know the diagnosis of their kidney mass (40%), the advice or information provided by healthcare professionals (40%), and not wishing to delay treatment (23%). Clinicians most frequently reported barriers to recommending RTB related to their uncertainty of diagnostic accuracy (56%), availability of appointments or hospital beds (52%), concerns of risk of bleeding (44%), risk of seeding (41%), and delays in meeting national cancer pathway targets (41%). The dissemination event was attended by 18 participants (seven patients and 11 clinicians). Suggestions to improve implementation included reducing variation and promotion of standardisation of practice by a consensus statement, increasing the evidence base (clinicians) and improved communication by developing better patient aids such as videos and diagrams (patients and clinicians).

CONCLUSION

Implementation of RTB may be dependent on the quality of information provided, its format and perceived reliability of the information. Increased utilisation of RTB may be improved by development of a consensus statement on the role of biopsy, with patients expressing a preference for alternative information aids such as patient videos.

The impact of sestamibi scan on clinical decision-making for renal masses: An observational single-center study

Introduction

We aimed to determine whether sestamibi scan changes management of renal masses.

Methods

All patients undergoing sestamibi scan for renal masses between 2008 and 2022 at a single center were retrospectively reviewed. Data were gathered on patient demographics, pre- and postoperative creatinine, sestamibi scan parameters, and cross-sectional imaging characteristics. Outcomes included whether the patient underwent renal mass biopsy or surgical resection and the final pathological diagnosis if tissue was obtained from biopsy or resection. Data regarding postbiopsy as well as postoperative complications were also collected. The odds ratio (OR) for surgery or biopsy based on sestamibi result was calculated.

Results

Forty-three patients underwent sestamibi scan from 2008 to 2022, with 10 scans consistent with oncocytoma and 33 with nononcocytoma. The mean tumor size at initial presentation was 4.0 ± 1.8 cm with a median RENAL score of 7 (range: 4-11). For patients with sestamibi scans negative for oncocytoma, the OR for surgery was 12.5 (95% confidence interval [CI]: 2.1-71.2, P = 0.005), and the OR for biopsy was 0.04 (95% CI: 0.005-0.39, P = 0.005). Conversely, for patients with sestamibi scans positive for oncocytoma, the OR for surgery was 0.28 (95% CI: 0.03-2.4, P = 0.24) and the OR for biopsy was 24.0 (95% CI: 2.6-222.7, P = 0.005). Creatinine at the last follow-up was similar between patients with positive and negative sestamibi scans. No patients experienced complications from surgery or biopsy. The median follow-up was 19 months (range: 2-163).

Conclusions

A sestamibi scan positive for oncocytoma led to increased use of renal mass biopsy for confirmation. Sestamibi scans that were negative for oncocytoma were more likely to result in surgical resection without biopsy.

Molecular Characterization of Metastatic Oncocytoma With Exceptional Response to Treatment: A Case Report

Comprehensive molecular characterization and effective therapy in a rare case of metastatic renal oncocytoma.

Diagnostic Biopsy for Small Renal Tumours: A Survey of Current European Practice

Background and objective

Renal tumour biopsy (RTB) can help in risk stratification of renal tumours with implications for management, but its utilisation varies. Our objective was to report current practice patterns, experiences, and perceptions of RTB and research gaps regarding RTB for small renal masses (SRMs).

Methods

Two web-based surveys, one for health care providers (HCPs) and one for patients, were distributed via the European Association of Urology Young Academic Urologist Renal Cancer Working Group and the European Society of Residents in Urology in January 2023.

Key findings and limitations

The HCP survey received 210 responses (response rate 51%) and the patient survey 54 responses (response rate 59%). A minority of HCPs offer RTB to >50% of patients (14%), while 48% offer it in <10% of cases. Most HCPs reported that RTB influences (61.5%) or sometimes influences (37.1%) management decisions. Patients were more likely to favour active treatment if RTB showed high-grade cancer and less likely to favour active treatment for benign histology. HCPs identified situations in which they would not favour RTB, such as cystic tumours and challenging anatomic locations. RTB availability (67%) and concerns about delays to treatment (43%) were barriers to offering RTB. Priority research gaps include a trial demonstrating that RTB leads to better clinical outcomes, and better evidence that benign/indolent tumours do not require active treatment.

Conclusions and clinical implications

Utilisation of RTB for SRMs in Europe is low, even though both HCPs and patients reported that RTB results can affect disease management. Improving timely access to RTB and generating evidence on outcomes associated with RTB use are priorities for the kidney cancer community.

Patient summary

A biopsy of a kidney mass can help patients and doctors make decisions on treatment, but our survey found that many patients in Europe are not offered this option. Better access to biopsy services is needed, as well as more research on what happens to patients after biopsy.

Stability of renal parenchymal volume and function during active surveillance of renal oncocytoma patients

INTRODUCTION AND OBJECTIVE

To evaluate whether significant loss in ipsilateral renal parenchymal volume (IRPV) and renal function occurs during active surveillance (AS) of renal oncocytoma (RO) patients.

METHODS

Renal function (estimated glomerular filtration rate, eGFR) dynamics were retrospectively analyzed in 32 consecutive biopsy-diagnosed RO patients managed with AS at a National Comprehensive Cancer Network institute. Three-dimensional kidney and tumor reconstructions were generated and IRPV was calculated using volumetry software (Myrian®) for all patients with manually estimated RO growth >+10 cm3. GFR and IRPV were compared at AS initiation vs. the last follow-up using 2-sided paired t-tests. The correlation between change in IRPV and change in RO size or GFR was tested using a Spearman coefficient.

RESULTS

With median follow-up of 37 months, there was no significant change between initial vs. last eGFR (median 71.0 vs. 70.5 ml/min/1.73 m2, P = 0.50; median change -3.0 ml/min/1.73 m2). Among patients (n = 17) with RO growth >+10 cm3 during AS (median growth +28.6 cm3, IQR +16.9- + 46.5 cm3), IRPV generally remained stable (median change +0.5%, IQR -1.2%- + 1.2%), with only 2 cases surpassing 5% loss. No IRPV loss was detected among any patient within the top tertile of RO growth magnitude. RO growth magnitude did not correlate with loss of either IRPV (ρ = -0.30, P = 0.24) or eGFR (ρ = -0.16, P = 0.40), including among patient subsets with lower initial eGFR. Study limitations include a lack of long-term follow-up.

CONCLUSIONS

Volumetry is a promising novel tool to measure kidney and tumor tissue changes during AS. Our study using volumetry indicates that clinically significant loss of IRPV or eGFR is uncommon and unrelated to tumor growth among untreated RO patients with intermediate follow-up. These findings support that AS is in general functionally safe for RO patients, however longer study is needed to determine safety durability, particularly among uncommon ≥cT2 RO variants.

Oncocytoma on renal mass biopsy: is it still the same histology when surgery is performed? Results from UroCCR-104 study

PURPOSE

To describe clinical features of patients with oncocytoma on renal biopsy (RMB), correlation with final histology on surgically treated patients, and predictive factors of discrepancy between RMB and final histology.

METHODS

This was a retrospective study conducted in the framework of the UroCCR project (NCT03293563). 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 report were excluded. Discrepancy between RMB and definitive histology was evaluated using a uni- and multivariable logistic regression analyses model.

RESULTS

Overall, 119 tumors with oncocytoma on RMB, from 15 centers, were included. Of those, 54 (45.4%) had upfront surgery and 65 (54.6%) had active surveillance (AS). In renal masses with initial active surveillance, with a median follow-up of 28 months, 23 (19.3%) underwent surgery, 4 (3.4%) received focal treatment and 38 (31.9%) remained on AS. 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 tumor (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).

CONCLUSION

Despite the increase of RMB in more and more centers, histologic discrepancy between RMB and definitive histology remains significant. This information should be discussed with patients and taken into consideration before treatment decision.

CT radiomics for differentiating oncocytoma from renal cell carcinomas: Systematic review and meta-analysis

BACKGROUND

Radiomics is a type of quantitative analysis that provides a more objective approach to detecting tumor subtypes using medical imaging. The goal of this paper is to conduct a comprehensive assessment of the literature on computed tomography (CT) radiomics for distinguishing renal cell carcinomas (RCCs) from oncocytoma.

METHODS

From February 15th 2012 to 2022, we conducted a broad search of the current literature using the PubMed/MEDLINE, Google scholar, Cochrane Library, Embase, and Web of Science. A meta-analysis of radiomics studies concentrating on discriminating between oncocytoma and RCCs was performed, and the risk of bias was assessed using the Quality Assessment of Diagnostic Accuracy Studies method. The pooled sensitivity, specificity, and diagnostic odds ratio were evaluated via a random-effects model, which was applied for the meta-analysis. This study is registered with PROSPERO (CRD42022311575).

RESULTS

After screening the search results, we identified 6 studies that utilized radiomics to distinguish oncocytoma from other renal tumors; there were a total of 1064 lesions in 1049 patients (288 oncocytoma lesions vs 776 RCCs lesions). The meta-analysis found substantial heterogeneity among the included studies, with pooled sensitivity and specificity of 0.818 [0.619-0.926] and 0.808 [0.537-0.938], for detecting different subtypes of RCCs (clear cell RCC, chromophobe RCC, and papillary RCC) from oncocytoma. Also, a pooled sensitivity and specificity of 0.83 [0.498-0.960] and 0.92 [0.825-0.965], respectively, was found in detecting oncocytoma from chromophobe RCC specifically.

CONCLUSIONS

According to this study, CT radiomics has a high degree of accuracy in distinguishing RCCs from RO, including chromophobe RCCs from RO. Radiomics algorithms have the potential to improve diagnosis in scenarios that have traditionally been ambiguous. However, in order for this modality to be implemented in the clinical setting, standardization of image acquisition and segmentation protocols as well as inter-institutional sharing of software is warranted.

Reliability and Management Outcomes Following a Percutaneous Biopsy Diagnosis of Oncocytoma: A 15-year Retrospective Analysis

Background There is uncertainty in the management of renal masses diagnosed as oncocytomas with image-guided percutaneous biopsy. Purpose To assess the reliability of a diagnosis of oncocytoma based on image-guided percutaneous renal mass biopsy and evaluate patient outcomes following different management strategies. Materials and Methods In this retrospective study, image-guided percutaneous biopsy pathology reports from April 2004 to April 2019 were searched for keywords "oncocytoma" and "oncocytic neoplasm" and compared with surgical pathology or repeat biopsy results. Patients with at least 12 months of clinical follow-up and known cause of death were grouped according to management strategies, and disease-specific survival and metastatic renal cell carcinoma (RCC)-free survival were compared. Mass growth rates were calculated with use of a normal linear mixed model. Results The database yielded 160 biopsy reports of 149 renal masses in 139 patients; 149 masses were categorized as oncocytoma (n = 107), likely oncocytoma (n = 12), oncocytic neoplasm (n = 28), and indeterminate with oncocytoma in differential (n = 2). Biopsied masses categorized as oncocytoma or likely oncocytoma were oncocytomas in 16 of 17 masses (94%) based on surgical pathology or repeat biopsy; four of eight masses (50%) categorized as oncocytic neoplasms were low-grade RCCs. Outcome analysis included 121 patients (mean age ± SD, 68 years ± 9.1; 82 men); 80 patients initially underwent active surveillance (11 were later treated), 33 underwent ablation, and eight underwent surgery. Disease-specific survival and metastatic-free survival were 100% after each management strategy (median follow-up, 86.6 months; range, 14.2-207.9 months). Mass growth rate (mean, 1.7 mm per year) showed no evidence of a significant difference among biopsy result categories (P = .37) or initial (P = .84) or final management strategies (P = .11). Conclusion Image-guided percutaneous biopsy diagnosis of renal oncocytoma was reliable. Although some masses diagnosed as oncocytic neoplasms were low-grade renal cell carcinomas (RCCs) at final diagnosis, no patients died of RCC, including those managed with active surveillance. © RSNA, 2023 See also the editorial by Lockhart in this issue.

Benefit and Harm of Active Surveillance for Biopsy-proven Renal Oncocytoma: A Systematic Review and Pooled Analysis

Context

Active surveillance (AS) of biopsy-proven renal oncocytomas may reduce overtreatment. However, on biopsy, the risk of misdiagnosis owing principally to entities with peculiar hybrids and overlap morphology, and phenotypes argues for early intervention.

Objective

To assess the benefit and harm of AS in biopsy-proven renal oncocytoma.

Evidence acquisition

A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA). We systematically searched PubMed, Scopus, and Web of Science databases from September 26 up to October 2021, for studies that analyzed the outcomes of AS in patients with biopsy-proven renal oncocytoma.

Evidence synthesis

A total of ten studies with 633 patients met our inclusion criteria and were included for analysis. After a median follow-up of 34.5 mo (95% confidence interval [CI] 30.6–38.4), the overall definitive treatment rate from AS to definitive treatment was 17.3% (n = 75/433, six studies). The pooled pathological agreement between the initial renal mass biopsy and the surgical pathology report was 91.1%. The main indications for surgery during follow-up were rapid tumor growth and patient request. The pooled median growth rate was 1.55 mm/yr (95% CI 0.9–2.2). No metastasis or death related to renal oncocytoma was reported.

Conclusions

Annual tumor growth of biopsy-proven renal oncocytoma is low. AS is oncologically safe, with favorable compliance of patients. Crossover to definitive treatment revealed a strong concordance between biopsy and final pathology. Further studies on the long-term outcomes of AS are needed.

Patient summary

In this study, we examined the benefit and harm of active surveillance (AS) in biopsy-proven oncocytoma. Based on the available data, AS appears oncologically safe and may represent a promising alternative to immediate treatment. Patients should be included in AS decision discussions.

Real world outcomes of biopsy-proven oncocytic neoplasm of the kidney managed by surveillance

Objectives

To evaluate outcomes of patients diagnosed with oncocytic renal neoplasms on routine renal mass biopsy and to describe the natural history of these tumours when managed with surveillance as opposed to immediate intervention. To report disease-specific survival.

Patients and methods

Patients were identified from a retrospective review of pathology databases from three tertiary referral centres that utilise renal mass biopsy in routine clinical practice. All patients with biopsy-proven oncocytic tumours were included and a retrospective review of online patient records was undertaken.

Results

There were 184 biopsy-proven oncocytic renal neoplasms identified in 172 patients. There were two biopsy complications (both pneumothorax, Clavien-Dindo Grade I). Of these lesions, 135 were reported as oncocytomas or oncocytic renal neoplasms that were not further classified and 37 were reported as chromophobe carcinoma (ChRCC). The median age at diagnosis was 70 (33-88). The average tumour diameter at diagnosis was 33 mm. One hundred seven tumours were initially managed with surveillance (including 13 ChRCC) with a minimum follow-up of 6 months and a median of 39 months (6-144) whereas 49 patients underwent immediate treatment. The mean growth rate across all oncocytic renal neoplasms managed by surveillance was 3 mm/year. There was no statistically significant difference in growth rates between oncocytic renal neoplasms and ChRCC. Thirteen patients with oncocytic renal neoplasms initially managed by surveillance moved on to an active management strategy during follow-up. The clinical indication given for a change from surveillance was tumour growth in 12 cases and patient choice in 1 case. Where definitive pathology was available, there was 85% concordance with the biopsy. There were no cases of development of metastatic disease or disease-related morbidity or mortality during the study.

Conclusions

This multicentre retrospective cohort study supports the hypothesis that selected biopsy-proven oncocytic renal neoplasms can be safely managed with surveillance in the medium term. Routine renal mass biopsy may reduce surgery for benign or indolent renal tumours and the potential associated morbidity for these patients.

Renal Oncocytoma: The Diagnostic Challenge to Unmask the Double of Renal Cancer

Renal oncocytoma represents the most common type of benign neoplasm that is an increasing concern for urologists, oncologists, and nephrologists due to its difficult differential diagnosis and frequent overtreatment. It displays a variable neoplastic parenchymal and stromal architecture, and the defining cellular element is a large polygonal, granular, eosinophilic, mitochondria-rich cell known as an oncocyte. The real challenge in the oncocytoma treatment algorithm is related to the misdiagnosis due to its resemblance, at an initial radiological assessment, to malignant renal cancers with a completely different prognosis and medical treatment. Unfortunately, percutaneous renal biopsy is not frequently performed due to the possible side effects related to the procedure. Therefore, the majority of oncocytoma are diagnosed after the surgical operation via partial or radical nephrectomy. For this reason, new reliable strategies to solve this issue are needed. In our review, we will discuss the clinical implications of renal oncocytoma in daily clinical practice with a particular focus on the medical diagnosis and treatment and on the potential of novel promising molecular biomarkers such as circulating microRNAs to distinguish between a benign and a malignant lesion.

Differential diagnosis of renal oncocytoma and chromophobe renal cell carcinoma using CT features: a central scar-matched retrospective study

BACKGROUND

Renal oncocytoma (RO) and chromophobe renal cell carcinoma (chRCC) have a common cellular origin and different clinical management and prognosis.

PURPOSE

To explore the utility of computed tomography (CT) in the differentiation of RO and chRCC.

MATERIAL AND METHODS

Twenty-five patients with RO and 73 patients with chRCC presenting with the central scar were included retrospectively. Two experienced radiologists independently reviewed the CT imaging features, including location, tumor size, relative density ratio, segmental enhancement inversion (SEI), necrosis, and perirenal fascia thickening, among others. Interclass correlation coefficient (ICC, for continuous variables) or Kappa coefficient test (for categorical variables) was used to determine intra-observer and inter-observer bias between the two radiologists.

RESULTS

The inter- and intra-reader reproducibility of the other CT imaging parameters were nearly perfect (>0.81) except for the measurements of fat (0.662). RO differed from chRCC in the cortical or medullary side (P = 0.005), relative density ratio (P = 0.020), SEI (P < 0.001), and necrosis (P = 0.045). The logistic regression model showed that location (right kidney), hypo-density on non-enhanced CT, SEI, and perirenal fascia thickening were highly predictive of RO. The combined indicators from logistic regression model were used for ROC analysis. The area under the ROC curve was 0.923 (P < 0.001). The sensitivity and specificity of the four factors combined for diagnosing RO were 88% and 86.3%, respectively. The correlation coefficient between necrosis and tumor size in all tumors including both of RO and chRCC was 0.584, indicating a positive correlation (P < 0.001).

CONCLUSION

The CT imaging features of location (right kidney), hypo-density on non-enhanced CT, SEI, and perirenal fascia thickening were valuable indicators in distinguishing RO from chRCC.

High-Resolution Ultrasonography of Renal Oncocytoma Presenting with Symptomatic Hematuria and Urinary Bladder Clot Retention-A Rare Occurrence

Renal oncocytomas are asymptomatic, benign tumors often encountered incidentally on various imaging modalities. Renal oncocytomas comprise 5–7% of primary renal neoplasms and are derived from cells of the distal renal tubule. We present a case report of renal oncocytoma in a 22-year-old male having right-sided flank pain and symptomatic gross hematuria with a giant urinary bladder clot retention. The tumor was excised, and the patient underwent laparoscopic partial nephrectomy. Typical features of renal oncocytoma were observed upon histopathological examination of the resected specimen. The patient was catheterized, and bladder irrigation with clot retraction was performed.

Quantitative image features from radiomic biopsy differentiate oncocytoma from chromophobe renal cell carcinoma

Purpose: To differentiate oncocytoma and chromophobe renal cell carcinoma (RCC) using radiomics features computed from spherical samples of image regions of interest, "radiomic biopsies" (RBs). Approach: In a retrospective cohort study of 102 CT cases [68 males (67%), 34 females (33%); mean age ± SD, 63 ± 12    years ], we pathology-confirmed 42 oncocytomas (41%) and 60 chromophobes (59%). A board-certified radiologist performed two RB rounds. From each RB round, we computed radiomics features and compared the performance of a random forest and AdaBoost binary classifier trained from the features. To control for overfitting, we performed 10 rounds of 70% to 30% train-test splits with feature-selection, cross-validation, and hyperparameter-optimization on each split. We evaluated the performance with test ROC AUC. We tested models on data from the other RB round and compared with the same round testing with the DeLong test. We clustered important features for each round and measured a bootstrapped adjusted Rand index agreement. Results: Our best classifiers achieved an average AUC of 0.71 ± 0.024 . We found no evidence of an effect for RB round ( p = 1 ). We also found no evidence for a decrease in model performance when tested on the other RB round ( p = 0.85 ). Feature clustering produced seven clusters in each RB round with high agreement ( Rand index = 0.981 ± 0.002 , p < 0.00001 ). Conclusions: A consistent radiomic signature can be derived from RBs and could help distinguish oncocytoma and chromophobe RCC.

Radiomics to better characterize small renal masses

PURPOSE

Radiomics is a specific field of medical research that uses programmable recognition tools to extract objective information from standard images to combine with clinical data, with the aim of improving diagnostic, prognostic, and predictive accuracy beyond standard visual interpretation. We performed a narrative review of radiomic applications that may support improved characterization of small renal masses (SRM). The main focus of the review was to identify and discuss methods which may accurately differentiate benign from malignant renal masses, specifically between renal cell carcinoma (RCC) subtypes and from angiomyolipoma without visible fat (fat-poor AML) and oncocytoma. Furthermore, prediction of grade, sarcomatoid features, and gene mutations would be of importance in terms of potential clinical utility in prognostic stratification and selecting personalised patient management strategies.

METHODS

A detailed search of original articles was performed using the PubMed-MEDLINE database until 20 September 2020 to identify the English literature relevant to radiomics applications in renal tumour assessment. In total, 42 articles were included in the analysis in 3 main categories related to SRM: prediction of benign versus malignant SRM, subtypes, and nuclear grade, and other features of aggressiveness.

CONCLUSION

Overall, studies reported the superiority of radiomics over expert radiological assessment, but were mainly of retrospective design and therefore of low-quality evidence. However, it is clear that radiomics is an attractive modality that has the potential to improve the non-invasive diagnostic accuracy of SRM imaging and prediction of its natural behaviour. Further prospective validation studies of radiomics are needed to augment management algorithms of SRM.

Active Surveillance for Biopsy Proven Renal Oncocytomas: Outcomes and Feasibility

OBJECTIVES

To report the outcomes and feasibility of active surveillance (AS) of biopsy-proven renal oncocytomas.

METHODS

Multicentric retrospective study (2010-2016) in 6 academic centers that included patients with biopsy-proven renal oncocytomas who were allocated to AS (imperative or elective indication) with a follow-up ≥1 year. Imaging was performed at least once a year, by CT-scan or ultrasound or MRI. Conversion to active treatment (surgical excision or ablative treatment) was at the discretion of the urologist. The primary endpoint was renal tumor growth (cm/year). Secondary outcomes included accuracy of biopsy, incidence, and reason to change AS to active treatment.

RESULTS

Eighty-nine patients were included: Median age 67 years (26-89) and median tumor size 26 mm [15-90] on diagnosis. During a mean follow-up of 43 months'' (median 36 [12-180]), mean tumor growth was 0.24 cm/year. No predictive factors (demographical, radiological or histologic) of tumor growth could be identified. Conversion from AS to active treatment occurred in 24 patients (27%) (13 surgical excisions, 11 ablative procedures), in a median time of 45 (12-76) months'' after diagnosis. Tumor growth was the main indication to convert AS to active treatment (58%) with 8% of the patients opting to discontinue AS. No patient had metastatic progression nor disease-specific death. The correlation between biopsy and surgical specimen was 92%.

CONCLUSION

Active surveillance for biopsy-proven renal oncocytomas was oncologically safe and patient adherence was high. No predictive factor for tumor growth could be identified but the tumor growth rate was low, and biopsy efficacy was high.

Growth and renal function dynamics of renal oncocytomas in patients on active surveillance

OBJECTIVES

To study the natural history of renal oncocytomas and address indications for intervention by determining how growth is associated with renal function over time, the reasons for surgery and ablation, and disease-specific survival.

PATIENTS AND METHODS

The study was conducted in a retrospective cohort of consecutive patients with renal oncocytoma on active surveillance reviewed at the Specialist Centre for Kidney Cancer at the Royal Free London NHS Foundation Trust (2012 to 2019). Comparison between groups was performed using Mann-Whitney U-tests and chi-squared tests. A mixed-effects model with a random intercept for patient was used to study the longitudinal association between tumour size and estimated glomerular filtration rate (eGFR).

RESULTS

Longitudinal data from 98 patients with 101 lesions were analysed. Most patients were men (68.3%) and the median (interquartile range [IQR]) age was 69 (13) years. The median (IQR) follow-up was 29 (26) months. Most lesions were small renal masses, and 24% measured over 4 cm. Over half (64.4%) grew at a median (IQR) rate of 2 (4) mm per year. No association was observed between tumour size and eGFR over time (P = 0.871). Nine lesions (8.9%) were subsequently treated. Two deaths were reported, neither were related to the diagnosis of renal oncocytoma.

CONCLUSION

Natural history data from the largest active surveillance cohort of renal oncocytomas to date show that renal function does not seem to be negatively impacted by growing oncocytomas, and confirms clinical outcomes are excellent after a median follow-up of over 2 years. Active surveillance should be considered the 'gold standard' management of renal oncocytomas up to 7cm.

Active surveillance for bilateral renal oncocytomas already resected on one side: a case report

INTRODUCTION

To report our experience of active surveillance of new bilateral masses after left laparoscopic partial nephrectomy for oncocytoma.

METHOD

A 67-year old man underwent left laparoscopic partial nephrectomy for a renal mass and histology confirmed oncocytoma. At follow-up magnetic resonance imaging (MRI) showed new renal bilateral masses: hence, sonogram-guided percutaneous core renal biopsies were performed confirming the presence of oncocytoma in both kidneys. A re-biopsy was required because of an increasing of the left mass while a histological was also consistent with oncocytoma.

RESULT

At follow of 8 years the patient is well and shows a normal renal function.

CONCLUSION

Oncocytomas show minimal growth rate or progression. MRI has an important role in the appropriate follow-up of renal oncocytomas. Patients with biopsy proven oncocytoma may be managed conservatively by active surveillance (AS).

Renal Oncocytoma: An Algorithm for Diagnosis and Management

Renal oncocytoma is an uncommon tumor that exhibits numerous features which are characteristic but not necessarily unique. Percutaneous biopsy is a safe method of diagnosis. However, differentiation from other tumor subtypes often requires sophisticated analysis and is not universally feasible. This is why, surgical management can be considered as a first-line treatment or after surveillance. Potential triggers for change in management are: tumor size >3 cm, stage progression, kinetics of size progression (>5 mm/y), and clinical change in patient or tumor factors. Long-term follow-up data are lacking and greater centralization should be considered to reach adequate management.

[Retrospective study of diagnosis and treatment of renal oncocytoma]

OBJECTIVE

To summarize the experience of diagnosis and surgical treatment of renal oncocytoma, and to evaluate the surgical results based on follow-up results, in order to find the best strategy.

METHODS

In the study, 21 cases with renal oncocytoma from December 2003 to April 2016 in Peking University Third Hospital were retrospectively analyzed, including 4 males, and 17 females, with 10 cases on the right side and 11 cases on the left side. Their age was between 15 to 80 years (average: 58 years). Ultrasound or CT examination after admission was conducted. Ultrasound examination showed solid nodules. CT manifestations were solid masses with enhancement, and the tumor size was between 1.5 cm to 6.5 cm (average: 3.3 cm). Of the 21 cases, 9 were located in the middle of kidney, 7 were located in the upper pole, and 5 were located in the lower pole. After preoperative examination, according to the size and location of the tumor, laparoscopic partial nephrectomy or laparoscopic nephrectomy was performed, respectively.

RESULTS

All the operations were successful, in which 17 cases underwent laparoscopic partial nephrectomy (including 3 cases which were converted to open surgery), and 4 cases underwent laparoscopic radical nephrectomy. The operation time ranged from 75 to 274 min (mean: 144 min), and the blood loss ranged from 10 to 1 000 mL (mean: 115 mL). The postoperative hospital stay time ranged from 6 to 13 d (average: 8.2 d). The pathological results were all renal oncocytoma. In the study, 17 cases were followed up while 4 cases were lost to follow-up. The follow-up time ranged from 12 to 175 months (mean: 44 months). One case died in 20 months after operation with unknown reason, and there were no recurrence or metastasis in the other 16 cases.

CONCLUSION

Renal oncocytoma is a benign tumor with good prognosis. Enhanced CT is an effective diagnostic method in assistant examination, but it is difficult to differentiate clear cell carcinoma only from the naked eye. It is worthwhile to measure CT value at different stages of the tumor by picture archiving and communication systems (PACS), and to compare with CT value of adjacent kidney tissue may improve the diagnostic efficiency of CT. Laparoscopic surgery is an effective treatment for renal oncocytoma. We recommend laparoscopic partial nephrectomy for the patients with renal oncocytoma as the best choice if conditions permit.

Imaging for the diagnosis and response assessment of renal tumours

PURPOSE

Imaging plays a key role throughout the renal cell carcinoma (RCC) patient pathway, from diagnosis and staging of the disease, to the assessment of response to therapy. This review aims to summarise current knowledge with regard to imaging in the RCC patient pathway, highlighting recent advances and challenges.

METHODS

A literature review was performed using Medline. Particular focus was paid to RCC imaging in the diagnosis, staging and response assessment following therapy.

RESULTS

Characterisation of small renal masses (SRM) remains a diagnostic conundrum. Contrast-enhanced ultrasound (CEUS) has been increasingly applied in this field, as have emerging technologies such as multiparametric MRI, radiomics and molecular imaging with 99mtechnetium-sestamibi single photon emission computed tomography/CT. CT remains the first-line modality for staging of locoregional and suspected metastatic disease. Although the staging accuracy of CT is good, limitations in determining nodal status persist. Response assessment following ablative therapies remains challenging, as reduction in tumour size may not occur. The pattern of enhancement on CT may be a more reliable indicator of treatment success. CEUS may also have a role in monitoring response following ablation. Response assessments following anti-angiogenic and immunotherapies in advanced RCC is an evolving field, with a number of alternative response criteria being proposed. Tumour response patterns may vary between different immunotherapy agents and tumour types; thus, future response criteria modifications may be inevitable.

CONCLUSION

The diagnosis and characterisation of SRM and response assessment following targeted therapy for advanced RCC are key challenges which warrant further research.

Oncocytoma managed by active surveillance in a transplant allograft kidney: a case report

BACKGROUND

The ethical implications of the utilization of kidneys with solid renal masses (SRMs) in transplantation are the subject of lively debate in the transplantation community and beyond. One of such implications is that as the life expectancy of renal transplant patients improve, the prevalence of SRMs in donors is likely to increase. We report a case of an oncocytoma in a renal allograft complicating a deceased-donor kidney transplant.

CASE PRESENTATION

A 60-year-old woman received and underwent deceased-donor renal transplantation for end-stage renal disease after a waiting-list period of 11 years. Kidney Doppler ultrasound (DUS) of the deceased donor was negative for any nodular lesion. The finding of the DUS, done on postoperative day 1, to assess the patency of the graft, was suspicious for an acute arterial thrombosis but did not reveal any focal irregularities. An ensuing computed tomography (CT) scan did not show any arterial complications but serendipitously revealed a 2.4-cm lesion on the upper pole of the renal allograft, which was not detected during the back-table or ultrasonography monitoring. Histology of the biopsied lesion was consistent with oncocytoma. However, because the eosinophilic variant of chromophobe renal cell carcinoma may morphologically resemble renal oncocytoma, immunohistochemical staining was performed. The results were negative, ruling out chromophobe RCC. After discussing the therapeutic options and potential related outcomes with the patient, we found no reason for resection of the lesion or an allograft nephrectomy, given the low risk of malignant transformation in an oncocytoma. Active surveillance of the benign tumor was done with ultrasonography, every 2 months, for the first year and, then, with magnetic resonance imaging, every year. The patient received mycophenolate-mofetil, tacrolimus, and prednisone throughout the 5-year follow-up period, and the regimen for immunosuppression was not changed despite the presence of the renal mass. After 60 months, we report that none of the radiological findings have shown any morphological changes of the lesion, and the patient is well.

CONCLUSION

To the best of our knowledge, we report the first case of an oncocytoma in a renal allograft complicating a deceased-donor kidney transplant, which was successfully managed by active surveillance.