Rationale for Percutaneous Biopsy and Histologic Characterisation of Renal Tumours

A systematic review on performance characteristics of FNA of renal lesions: It is time for a standardized classification system

BACKGROUND

The incidence of renal tumors has steadily increased over the past decade. In this study, the authors performed a systematic review and analysis of the literature on renal fine-needle aspiration (FNA) to determine its performance and explore whether a standardized classification system can be used for reporting renal FNA cytology.

METHODS

A systematic search of published articles on renal FNA was conducted. The data on FNA and histologic diagnosis were extracted and categorized, and the risk of malignancy was calculated. Different scenarios were used to estimate FNA performance statistics.

RESULTS

Of the 3766 potentially relevant studies, 23 met the inclusion criteria of the study. The 2231 FNA cases included were re-categorized according to the classification system, rendering 142 (6.36%) nondiagnostic, 270 (12.1%) nonneoplastic, 271 (12.14%) benign neoplasm, 65 (2.91%) renal neoplasm with unknown malignant potential, oncocytic type, 25 (1.12%) atypia of undetermined significance, 60 (2.68%) suspicious for malignancy, and 1398 (62.66%) malignant FNA diagnoses. The risk of malignancy in these cases was 65.4%, 18.1%, 16.6%, 16.9%, 60%, 73.3%, and 96.9%, respectively. According to the classification system, the study indicated that the accuracy of renal FNA was between 91% and 95%, the sensitivity was 90.9%-96.7%, and the specificity was 82%-92% in different scenarios.

CONCLUSIONS

There is a need for a standardized reporting in renal cytology that will improve the sensitivity and accuracy of renal cytology, reduce the rate of indeterminate diagnoses, and alter the management strategies of renal lesions. Based on the available literature, a new reporting system is proposed, including categories with an associated risk of malignancy.

Stepwise algorithm using computed tomography and magnetic resonance imaging for differential diagnosis of fat-poor angiomyolipoma in small renal masses: A prospective validation study

OBJECTIVES

To validate the diagnostic accuracy of a stepwise algorithm to differentiate fat-poor angiomyolipoma (fp-AML) from renal cancer in small renal masses (SRMs).

METHODS

We prospectively enrolled 223 patients with solid renal masses <4 cm and no visible fat on unenhanced computed tomography (CT). Patients were assessed using an algorithm that utilized the dynamic CT and MRI findings in a stepwise manner. The diagnostic accuracy of the algorithm was evaluated in patients whose histology was confirmed through surgery or biopsy. The clinical course of the patients was further analyzed.

RESULTS

The algorithm classified 151 (68%)/42 (19%)/30 (13%) patients into low/intermediate/high AML probability groups, respectively. Pathological diagnosis was made for 183 patients, including 10 (5.5%) with fp-AML. Of these, 135 (74%)/36 (20%)/12 (6.6%) were classified into the low/intermediate/high AML probability groups, and each group included 1 (0.7%)/3 (8.3%)/6 (50%) fp-AMLs, respectively, leading to the area under the curve for predicting AML of 0.889. Surgery was commonly opted in the low and intermediate AML probability groups (84% and 64%, respectively) for initial management, while surveillance was selected in the high AML probability group (63%). During the 56-month follow-up, 36 (82%) of 44 patients initially surveyed, including 13 of 18 (72%), 6 of 7 (86%), and 17 of 19 (89%) in the low/intermediate/high AML probability groups, respectively, continued surveillance without any progression.

CONCLUSIONS

This study confirmed the high diagnostic accuracy for differentiating fp-AMLs. These findings may help in the management of patients with SRMs.

Radiomics Machine Learning Analysis of Clear Cell Renal Cell Carcinoma for Tumour Grade Prediction Based on Intra-Tumoural Sub-Region Heterogeneity

BACKGROUND

Renal cancers are among the top ten causes of cancer-specific mortality, of which the ccRCC subtype is responsible for most cases. The grading of ccRCC is important in determining tumour aggressiveness and clinical management.

OBJECTIVES

The objectives of this research were to predict the WHO/ISUP grade of ccRCC pre-operatively and characterise the heterogeneity of tumour sub-regions using radiomics and ML models, including comparison with pre-operative biopsy-determined grading in a sub-group.

METHODS

Data were obtained from multiple institutions across two countries, including 391 patients with pathologically proven ccRCC. For analysis, the data were separated into four cohorts. Cohorts 1 and 2 included data from the respective institutions from the two countries, cohort 3 was the combined data from both cohort 1 and 2, and cohort 4 was a subset of cohort 1, for which both the biopsy and subsequent histology from resection (partial or total nephrectomy) were available. 3D image segmentation was carried out to derive a voxel of interest (VOI) mask. Radiomics features were then extracted from the contrast-enhanced images, and the data were normalised. The Pearson correlation coefficient and the XGBoost model were used to reduce the dimensionality of the features. Thereafter, 11 ML algorithms were implemented for the purpose of predicting the ccRCC grade and characterising the heterogeneity of sub-regions in the tumours.

RESULTS

For cohort 1, the 50% tumour core and 25% tumour periphery exhibited the best performance, with an average AUC of 77.9% and 78.6%, respectively. The 50% tumour core presented the highest performance in cohorts 2 and 3, with average AUC values of 87.6% and 76.9%, respectively. With the 25% periphery, cohort 4 showed AUC values of 95.0% and 80.0% for grade prediction when using internal and external validation, respectively, while biopsy histology had an AUC of 31.0% for the classification with the final grade of resection histology as a reference standard. The CatBoost classifier was the best for each of the four cohorts with an average AUC of 80.0%, 86.5%, 77.0% and 90.3% for cohorts 1, 2, 3 and 4 respectively.

CONCLUSIONS

Radiomics signatures combined with ML have the potential to predict the WHO/ISUP grade of ccRCC with superior performance, when compared to pre-operative biopsy. Moreover, tumour sub-regions contain useful information that should be analysed independently when determining the tumour grade. Therefore, it is possible to distinguish the grade of ccRCC pre-operatively to improve patient care and management.

Special Issue Editorial: Emerging Therapies in Renal Cell Carcinoma: The Road to a Cure?

In the past two decades, therapy development in the treatment of renal cell carcinoma has exploded [...].

Head-to-head comparisons of enhanced CT, 68Ga-PSMA-11 PET/CT and 18F-FDG PET/CT in identifying adverse pathology of clear-cell renal cell carcinoma: a prospective study

OBJECTIVES

Accurate preoperative prediction of adverse pathology is crucial for treatment planning of renal cell carcinoma (RCC). Previous studies have emphasized the potential of prostate-specific membrane antigen positron emission tomography / computed tomography (PSMA PET/CT) in differentiating between benign and malignant localized renal tumors. However, there is a scarcity of case reports elucidating the identification of aggressive pathological features using PET/CT. Our study was designed to prospectively compare the diagnostic value of enhanced CT, 68Ga-PSMA-11 and 18F-fluorodeoxyglucose (18F-FDG) PET/CT in clear-cell renal cell carcinoma (ccRCC) with necrosis or sarcomatoid or rhabdoid differentiation.

MATERIALS AND METHODS

A prospective case series of patients with a newly diagnosed renal mass who underwent enhanced CT, 68Ga-PSMA-11 and 18F-FDG PET/CT within 30 days prior to nephrectomy was included. Complete preoperative and postoperative clinicopathological data were recorded. Patients who received neoadjuvant targeted therapy, declined enhanced CT or PET/CT scanning, refused surgical treatment or had non-ccRCC pathological indications were excluded. Radiological parameters were compared within subgroups of pathological characteristics. Bonferroni corrections were used to adjust for multiple testing and statistical significance was set at a p-value less than 0.017.

RESULTS

Seventy-two patients were available for the final analysis. Enhanced CT demonstrated poor performance in identifying necrosis, sarcomatoid or rhabdoid differentiation and adverse pathology (all P > 0.05). The maximum standardized uptake value (SUVmax) of 68Ga-PSMA-11 PET/CT was more effective than 18F-FDG PET/CT in identifying tumor necrosis and adverse pathology, with an area under the curve (AUC) of 0.85 (cutoff value=25.26, p<0.001; Delong test z=2.709, p=0.007) for tumor necrosis and AUC of 0.90 (cutoff value=25.26, p<0.001; Delong test z=3.433, p<0.001) for adverse pathology. However, no significant statistical difference was found between 68Ga-PSMA-11 and 18F-FDG PET/CT in predicting sarcomatoid or rhabdoid feature (AUC of 0.91 vs.0.75, Delong test z=1.998, p=0.046). Subgroup analyses based on age, sex, tumor location, maximal diameter, stage and WHO/ISUP grade demonstrated that 68Ga-PSMA-11 PET/CT SUVmax had a significant predictive value for adverse pathology. Enhanced CT value and SUVmax demonstrated strong reliability [intraclass correlation coefficient (ICC) > 0.80], indicating a robust correlation.

CONCLUSIONS

68Ga-PSMA-11 PET/CT demonstrates distinct advantages in identifying aggressive pathological features of primary ccRCC when compared to enhanced CT and 18F-FDG PET/CT. Further research and assessment are warranted to fully establish the clinical utility of 68Ga-PSMA-11 PET/CT in ccRCC.

[Renal Biopsy]

The extent of renal biopsy indication is being widened because of the increasing incidence of incidental renal masses; the increasing treatment options for renal cell carcinoma, including ablation therapy and novel targeted treatment; and the increasing incidence of kidney transplantation. However, percutaneous renal biopsy is technically difficult, particularly for beginners, because the skin-to-organ distance is relatively longer than those associated with other organs. In the present review, we will discuss the indications, technical considerations, efficacy, and complications of renal biopsy. Furthermore, we share practical tips of renal biopsy through many examples to help radiologists perform renal biopsy safely and effectively in various situations.

The Utility of Renal Mass Biopsy in Shared Decision-Making for Renal Mass Treatment

OBJECTIVE

To evaluate the utility of renal mass biopsy (RMB) in shared decision-making for renal mass treatment. Underutilization of RMB for patients with renal masses is due in part to physicians believing that results have limited clinical utility.

MATERIALS AND METHODS

This was a prospective study of all patients referred for RMB from October 2019 to October 2021. Patients and physicians completed pre- and post-RMB questionnaires. Questionnaires assessed both parties' perceived utility of RMB and the impact of biopsy results on treatment preference using Likert scales.

RESULTS

We enrolled 22 patients with a mean age of 66years (SD 14.5) and mean renal tumor size 3.1 cm (SD 1.4). Five were lost to follow-up (three pre-RMB, two post-RMB). Pre-RMB, 100% of patients believed that a biopsy would help them choose a treatment and 45% were unsure of their treatment preferences. After RMB, 92% perceived their biopsy results as useful and only 9% were unsure of treatment preference. Overall, 100% of patients were glad they had a biopsy. Results led patients and physicians to change their treatment preference in 57% and 40% of cases, respectively. Patients and physicians disagreed about treatment in 81% of cases prior to biopsy, but in only 25% of cases after biopsy.

CONCLUSION

Discordance between patient and physician treatment preference for renal masses is higher in the absence of RMB data. Select patients are willing to undergo RMB and RMB data can increase patient confidence and comfort in a shared decision-making approach for renal mass treatment.

"Could Patient Age and Gender, along with Mass Size, Be Predictive Factors for Benign Kidney Tumors?": A Retrospective Analysis of 307 Consecutive Single Renal Masses Treated with Partial or Radical Nephrectomy

Due to the increased use of common and non-invasive abdominal imaging techniques over the last few decades, the diagnosis of about 60% of renal tumors is incidental. Contrast-enhancing renal nodules on computed tomography are diagnosed as malignant tumors, which are often removed surgically without first performing a biopsy. Most kidney nodules are renal cell carcinoma (RCC) after surgical treatment, but a non-negligible rate of these nodules may be benign on final pathology; as a result, patients undergo unnecessary surgery with an associated significant morbidity. Our study aimed to identify a subgroup of patients with higher odds of harboring benign tumors, who would hence benefit from further diagnostic examinations (such as renal biopsy) or active surveillance. We performed a retrospective review of the medical data, including pathology results, of patients undergoing surgery for solid renal masses that were suspected to be RCCs (for a total sample of 307 patients). Owing to the widespread use of common and non-invasive imaging techniques, the incidental diagnosis of kidney tumors has become increasingly common. Considering that a non-negligible rate of these tumors is found to be benign after surgery at pathological examination, it is crucial to identify features that can correctly diagnose a mass as benign or not. According to our study results, female sex and tumor size ≤ 3 cm were independent predictors of benign disease. Contrary to that demonstrated by other authors, increasing patient age was also positively linked to a greater risk of malign pathology.

Cystic Renal Masses: Old and New Paradigms

Cystic renal masses describe a spectrum of lesions with benign and/or malignant features. Cystic renal masses are most often identified incidentally with the Bosniak classification system stratifying their malignant potential. Solid enhancing components most often represent clear cell renal cell carcinoma yet display an indolent natural history relative to pure solid renal masses. This has led to an increased adoption of active surveillance as a management strategy in those who are poor surgical candidates. This article provides a contemporary overview of historical and emerging clinical paradigms in the diagnosis and management of this distinct clinical entity.

Multiparametric magnetic resonance imaging for characterizing renal tumors: A validation study of the algorithm presented by Cornelis et al

Objectives

In the last decade, the incidence of renal cell carcinoma (RCC) has been rising, with the greatest increase observed for solid tumors. Magnetic resonance imaging (MRI) protocols and algorithms have recently been available for classifying RCC subtypes and benign subtypes. The objective of this study was to prospectively validate the MRI algorithm presented by Cornelis et al. for RCC classification.

Material and Methods

Over a 7-month period, 38 patients with 44 renal tumors were prospectively included in the study and received an MRI examination in addition to the conventional investigation program. The MRI sequences were: T2-weighted, dual chemical shift MRI, diffusion-weighted imaging (DWI), and dynamic contrast-enhanced T1-weighted in wash-in and wash-out phases. The images were evaluated according to the algorithm by two experienced, blinded radiologists, and the histopathological diagnosis served as the gold standard.

Results

Of 44 tumors in 38 patients, only 8 tumors (18.2%) received the same MRI diagnosis according to the algorithm as the histopathological diagnosis. MRI diagnosed 16 angiomyolipoma, 14 clear cell RCC (ccRCC), 12 chromophobe RCC (chRCC), and two papillary RCC (pRCC), while histopathological examination diagnosed 24 ccRCC, four pRCC, one chRCC, and one mixed tumor of both pRCC and chRCC. Malignant tumors were statistically significantly larger than the benign (3.16 ± 1.34 cm vs. 2.00 ± 1.04 cm, P = 0.006).

Conclusion

This prospective study could not reproduce Cornelis et al.'s results and does not support differentiating renal masses using multiparametric MRI without percutaneous biopsy in the future. The MRI algorithm showed few promising results to categorize renal tumors, indicating histopathology for clinical decisions and follow-up regimes of renal masses are still required.

HIGH RISK DISEASE AND POOR FOLLOWUP: THE IMPORTANCE OF RENAL MASS BIOPSY IN A COHORT OF VETERANS

OBJECTIVE

To assess the clinical utility of RMB in our multi-state system. Renal mass biopsy (RMB) is useful in the management of masses ≤ 4 cm (T1a), but evaluation of RMB in the uniquely vulnerable Veteran population is lacking.

METHODS

136 RMB in 130 patients performed between 06/2015 and 11/2020 were identified in this Quality Improvement analysis. Demographics, size, pathology, treatment, and biopsy complications were analyzed. Of 101 T1a masses, 89 were either diagnostic or not decompressed cysts and 77 met inclusion criteria for follow-up imaging compliance analysis.

RESULTS

The median age was 66 years. The diagnostic rate was 94.1% (128/136) for all masses and 94.1% (95/101) for T1a renal masses, with a complication rate of 2.2%. Among solid T1a masses, unexpectedly aggressive lesions (Fuhrman Grade 4, Type 2 papillary or sarcomatoid features) were identified in 8/89 (9.0%). 57 (64%) patients were treated with cryoablation or surgery and 32 (36%) patients elected active surveillance (AS). A neoplastic finding (oncocytoma or RCC) was present in 16 patients choosing AS (50%) compared to 52 patients choosing treatment (91%). Compliance with NCCN-recommended imaging was 50% and 47% for AS and treatment groups, respectively.

CONCLUSIONS

In this VA cohort, we found a significant incidence of high-risk lesions and poor compliance with follow-up imaging. Aggressive biopsy protocols with high consideration of treatment may be appropriate to limit risk in those lost to follow-up. Given that 9% of our small renal masses were highly aggressive, biopsy may be critical in the selection of AS candidates.

Diagnostics and prognostic evaluation in renal cell tumors: the German S3 guidelines recommendations

The German guidelines on renal cell carcinoma (RCC) have been developed at highest level of evidence based on systematic literature review. In this paper, we are presenting the current recommendations on diagnostics including preoperative imaging and imaging for stage evaluation as well as histopathological classification. The role of tumor biopsy is further discussed. In addition, different prognostic scores and the status of biomarkers in RCC are critically evaluated.

The impact of tumor size on the survival of patients with small renal masses: A population-based study

Background

Active surveillance (AS) with delayed intervention has gained acceptance as a management strategy for small renal masses (SRMs). However, during AS, there is a risk of tumor growth. Thus, we aim to investigate whether tumor growth in patients with SRMs leads to tumor progress.

Methods

In this study, we enrolled 16,070 patients from the Surveillance, Epidemiology, and End Results database with T1a renal cell carcinoma (RCC) between 2004 and 2017. The 16,070 patients were divided into three groups: 10,526 in the partial nephrectomy (PN) group, 2768 in the local ablation (LA) group, and 2776 in the AS group. Associations of tumor size with all‐cause and cancer‐specific mortality were evaluated using Kaplan–Meier analyses and Cox regression models.

Results

Four tumor size categories were delineated (≤1, >1–2, >2–3, and > 3–4 cm in diameter), and 10‐year all‐cause and cancer‐specific mortality both significantly increased with increasing tumor size in the PN, LA, and AS groups (all p < 0.05). Tumors were substaged based on diameter: T1aA (≤2 cm) and T1aB (>2–4 cm). All‐cause and cancer‐specific mortality were significantly higher in T1aB tumors than T1aA tumors in each group (hazard ratio = 1.395 and 1.538, respectively; all p < 0.05).

Conclusions

Tumor growth relates to worse prognosis of T1a RCC, and 2 cm serves as a size threshold that is prognostically relevant for patients with T1a RCC. Because of the lack of accurate predictors of tumor growth rate, AS for patients with SRMs incurs a risk of tumor progression.

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.

Metastasis of breast cancer to the right kidney with a tumor thrombus in the inferior vena cava: a case report

Background

It is quite rare for breast cancer to metastasize to the kidney with a tumor thrombus in the inferior vena cava.

Case presentation

A Japanese woman in her forties was diagnosed with cancer of the left breast and underwent left mastectomy with sentinel lymph node biopsy. The final pathological diagnosis was pT1aN0M0, stage IA (ER positive, PgR positive, HER2 negative). Thirteen years later, she presented for care with the complaint of abdominal pain. By imaging findings, right renal carcinoma with a tumor thrombus in the inferior vena cava and lung metastases was suspected. However, her tumors were refractory to molecular targeted therapy. In addition, CT-guided needle biopsy of the kidney and lung lesions was done and it was revealed that lesions of the left lung and the right kidney was breast cancer metastases (ER positive, PgR positive, HER2 negative). The patient started combination therapy consisting of abemaciclib, tamoxifen and leuprorelin. Six months later, she died from progression of her metastatic disease.

Conclusions

It is sometimes difficult to differentiate between primary renal cancer and kidney metastases from breast cancer on imaging. Renal biopsy is recommended before commencing treatment.

Percutaneous biopsy of small renal mass: can diagnostic accuracy be affected by hospital volume?

Introduction

High diagnostic performance and low morbidity for renal tumor biopsy (RTB) have been described in highly experienced centers. Here we present the five-year experience of our institute in performing RTB. The protocol used, the safety profile and the diagnostic accuracy obtained were analyzed.

Material and methods

The study is a retrospective single-institution clinical data review of 84 consecutive RTB of small renal masses. Post-biopsy complications were reported using the Clavien-Dindo system. To measure the concordance between biopsy and nephrectomy specimens regarding histological subtype and International Society of Urological Pathology/World Health Organization (ISUP/WHO) renal cell carcinoma grade, the kappa coefficient of Cohen was used.

Results

Median (IQR) follow-up time was 44 (29–58) months. In total, 94% of RTB procedures were free of complications; when complications did occur, 80% were grade I and 20% were grade II. No cases of tumor seeding were observed. Combining the first and repeated biopsies the overall diagnostic rate was 85.8%. Overall, 79.1% of diagnostic RTB were malignant. In 42 surgically treated patients, the concordance between the histological results of biopsies and surgical specimens was very good for histological subtypes (k = 0.87) and moderate for tumor grade (k = 0.51).

Conclusions

RTB resulted in a high safety profile. The overall diagnostic rate was 85% and an unnecessary intervention was avoided in 21% of patients. RTB showed a very good accuracy in determining the histological subtype of renal cancer while it was moderate for the tumor grade. These results are similar to those reported in larger series and support feasibility of this procedure in low-volume centers.

Computed Tomography-guided Core Needle Biopsy for Renal Tumors: A Review

Small renal tumors are sometimes challenging to diagnose accurately through imaging alone, and image-guided biopsies are performed when histological diagnoses are needed. Although ultrasound guidance is usually chosen for renal tumor biopsies, computed tomography guidance is preferred for selected cases; e.g., obese patients or when the target is undetectable by ultrasound (as those in the upper pole). In the 14 recently published studies covering ≥50 procedures, computed tomography-guided renal tumor biopsies had a wide range diagnostic yield (67.4%-97.4%). Complications often occurred; however, most were minor and asymptomatic. No biopsy-related deaths and tumor seeding occurred. This study aimed to review the advantages and disadvantages, procedure techniques, diagnostic yields, and complications of core needle biopsies for renal tumors under computed tomography guidance.

Renal Tumor Biopsy: Rationale to Avoid Surgery in Small Renal Masses

PURPOSE OF REVIEW

The use of renal tumor biopsy (RTB) for small renal masses (SRMs) in daily practice, although safe and accurate, is unusual. Considering the large number of benign tumors in patients with renal masses < 4 cm, some patients with benign tumors are directly referred for surgery instead. This study aimed to report the diagnostic rates of RTB, determine the concordance with surgical pathology, and assess the number of procedures that could have been avoided. We retrospectively studied 255 patients who underwent RTB at our institution in 2010-2019. Of them, 73 were excluded from the analysis (exclusion criteria: > 4 cm, cystic lesion, missing data). The remaining 182 with undetermined SRMs ≤ 4 cm underwent RTB under computed tomography guidance.

RECENT FINDINGS

Biopsies were diagnostic in 154/182 (84.6%) cases. Of the non-diagnostic biopsies, 11 were diagnostic when repeated. When RTB was performed of all undetermined SRMs, active treatment (surgery or cryotherapy) was avoided in 50/182 patients (27.5%) because of a benign diagnosis, while 9/182 patients (4.9%) underwent surveillance after a shared multidisciplinary decision. The overall diagnostic rate was 90.6%. All adverse events (approximately 4%) were Clavien-Dindo grade I and did not require active treatment. RTB histology results and nuclear grade were highly concordant with the final pathology (96% and 86.6%, respectively). On univariate logistic regression analysis, male sex was the only contributing factor of diagnostic biopsy. RTB of SRMs should be performed more frequently as part of a multidisciplinary decision-making process since it avoided unnecessary surgical treatment in 1 of 3 patients in our institution.

Evaluation of radiomics and machine learning in identification of aggressive tumor features in renal cell carcinoma (RCC)

PURPOSE

The purpose of this study was to evaluate the use of CT radiomics features and machine learning analysis to identify aggressive tumor features, including high nuclear grade (NG) and sarcomatoid (sarc) features, in large renal cell carcinomas (RCCs).

METHODS

CT-based volumetric radiomics analysis was performed on non-contrast (NC) and portal venous (PV) phase multidetector computed tomography images of large (> 7 cm) untreated RCCs in 141 patients (46W/95M, mean age 60 years). Machine learning analysis was applied to the extracted radiomics data to evaluate for association with high NG (grade 3-4), with multichannel analysis for NG performed in a subset of patients (n = 80). A similar analysis was performed in a sarcomatoid rich cohort (n = 43, 31M/12F, mean age 63.7 years) using size-matched non-sarcomatoid controls (n = 49) for identification of sarcomatoid change.

RESULTS

The XG Boost Model performed best on the tested data. After manual and machine feature extraction, models consisted of 3, 7, 5, 10 radiomics features for NC sarc, PV sarc, NC NG and PV NG, respectively. The area under the receiver operating characteristic curve (AUC) for these models was 0.59, 0.65, 0.69 and 0.58 respectively. The multichannel NG model extracted 6 radiomic features using the feature selection strategy and showed an AUC of 0.67.

CONCLUSIONS

Statistically significant but weak associations between aggressive tumor features (high nuclear grade, sarcomatoid features) in large RCC were identified using 3D radiomics and machine learning analysis.

Utilization of Renal Mass Biopsy for T1 Renal Lesions across Michigan: Results from MUSIC-KIDNEY, A Statewide Quality Improvement Collaborative

BACKGROUND

Renal mass biopsy (RMB) has had limited and varied utilization to guide management of renal masses (RM).

OBJECTIVE

To evaluate utilization of RMB for newly diagnosed cT1 RMs across diverse practice types and assess associations of outcomes with RMB.

DESIGN SETTING AND PARTICIPANTS

MUSIC-KIDNEY commenced data collection in September 2017 for all newly presenting patients with a cT1 RM at 14 diverse practices. Patients were assessed at ≥120 d after initial evaluation.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Demographics and outcomes were compared for patients undergoing RMB versus no RMB. Clinical and demographic characteristics were summarized by RMB status using a χ2 test for categorical variables and Student t test for continuous variables. A mixed-effects logistic regression model was constructed to identify associations with RMB receipt.

RESULTS AND LIMITATIONS

RMB was performed in 15.5% (n = 282) of 1808 patients with a cT1 RM. Practice level rates varied from 0% to 100% (p = 0.001), with only five of 14 practices using RMB in >20% of patients. On multivariate analysis, predictors of RMB included greater comorbidity (Charlson comorbidity index ≥2 vs 0: odds ratio [OR] 1.44; p = 0.025) and solid lesion type (cystic vs solid: OR 0.17; p = 0.001; indeterminate vs solid: OR 0.58; p = 0.01). RMB patients were less likely to have benign pathology at intervention (5.0% vs 13.5%; p = 0.01). No radical nephrectomies were performed for patients with benign histology at RMB. The limitations include short follow-up and inclusion of practices with low numbers of RMBs.

CONCLUSIONS

Utilization of RMB varied widely across practices. Factors associated with RMB include comorbidities and lesion type. Patients undergoing RMB were less likely to have benign histology at intervention.

PATIENT SUMMARY

Current use of biopsy for kidney tumors is low and varies across our collaborative. Biopsy was performed in patients with greater comorbidity (more additional medical conditions) and for solid kidney tumors. Pretreatment biopsy is associated with lower nonmalignant pathology detected at treatment.

Open Versus Percutaneous Approach of Renal Tumor Biopsy at Cipto Mangunkusumo Hospital: A Single-center Experience

BACKGROUND: Renal tumor biopsy is beneficial as it is capable of distinguishing between histological types of renal tumor; hence, it plays an important role in deciding the best therapy regimen. AIM: This study aims to evaluate the clinical experiences of renal biopsy in Cipto Mangunkusumo National Referral Hospital (RSCM), with both a percutaneous and open approach. It also aims to analyze the indications, results, intraoperative information, and complications of the two approaches. METHODS: This study was conducted using the retrospective cohort design; meanwhile, data were collected from RSCM from 1990 to 2019. The biopsy sample was taken using percutaneous and open renal biopsy, while comparative analysis was done between the two biopsy approaches. RESULTS: Data were collected from 33 patients that underwent renal biopsy from 1990 to 2019. Majority of the cases were diagnosed as unresectable renal tumor, while histological examination found clear cell carcinoma in most of the cases (73%). Furthermore, the open approach showed longer duration and higher blood loss compared to percutaneous technique with median 60 (30–120) versus 30 (5–60) min (p < 0.001) and 100 (5–650) versus 2 (1–5) ml (p < 0.001), respectively. In general, complications were reported to be low for both techniques. CONCLUSION: Based on the results, percutaneous renal biopsy has similar efficacy and complications rates in tumor sampling for histopathology together with open approach. However, there were significant differences in the duration and blood loss; hence, percutaneous biopsy is more favorable.

Immunocytochemistry for diagnostic cytopathology-A practical guide

Cytological specimens, which are obtained by minimally invasive methods, are an excellent source of diagnostic material. Sometimes they are the only material available for diagnosis as well as for prognostic/predictive markers. When cytomorphology is not straightforward, ancillary tests may be required for a definitive diagnosis to guide clinical management. Immunocytochemistry (ICC) is the most common and practical ancillary tool used to reach a diagnosis when cytomorphology is equivocal, to differentiate entities with overlapping morphological features, and to determine the cell lineage and the site of origin of a metastatic neoplasm. Numerous immunomarkers are available, and some are expressed in multiple neoplasms. To rule out entities within a differential diagnosis, the use of more than one marker, sometimes panels, is necessary. ICC panels for diagnostic purposes should be customised based on the clinical context and cytomorphology, and the markers should be used judiciously to preserve material for additional tests for targeted therapies in the appropriate setting. This review offers a practical guide for the use of ICC for diagnostic cytopathology, covering the most commonly encountered non-hematolymphoid diagnostic scenarios in various body sites.

Consensus statements on the management of metastatic renal cell carcinoma from the Hong Kong Urological Association and the Hong Kong Society of Uro-Oncology 2019

BACKGROUND

To establish a set of consensus statements for the management of metastatic renal cell carcinoma, a total of 12 urologists and clinical oncologists from two professional associations in Hong Kong formed an expert consensus panel.

METHODS

Through a series of meetings and using the modified Delphi method, the panelists presented recent evidence, discussed clinical experiences, and drafted consensus statements on several areas of focus regarding the management of metastatic renal cell carcinoma. Each statement was eventually voted upon by every panelist based on the practicability of recommendation.

RESULTS

A total of 46 consensus statements were ultimately accepted and established by panel voting.

CONCLUSIONS

Derived from recent evidence and expert insights, these consensus statements were aimed at providing practical guidance to optimize metastatic renal cell carcinoma management and promote a higher standard of clinical care.

The Nephrologist's Management of Renal Cell Carcinoma After Kidney Surgery

Renal cell carcinoma is associated with chronic kidney disease as well as with common risk factors including hypertension and diabetes mellitus. Localized renal cell carcinoma is treated surgically and in these cases has a favorable prognosis. In particular, in those individuals with small renal masses (≤4 cm), preservation of kidney function should be prioritized. Postoperative chronic kidney disease or end-stage renal disease prevention should include baseline kidney function and risk factor assessment, nontumor renal biopsy, as well as counseling on treatment options to discuss maximizing kidney function preservation. Postnephrectomy prognosis can be determined with repeat laboratory and clinical assessment. Ultimately, early involvement of the nephrologist in a multidisciplinary team including the urology team will enable the reduction of postsurgical kidney disease related morbidity and potentially mortality.

ACR Appropriateness Criteria® Indeterminate Renal Mass

Renal masses are increasingly detected in asymptomatic individuals as incidental findings. CT and MRI with intravenous contrast and a dedicated multiphase protocol are the mainstays of evaluation for indeterminate renal masses. A single-phase postcontrast dual-energy CT can be useful when a dedicated multiphase renal protocol CT is not available. Contrast-enhanced ultrasound with microbubble agents is a useful alternative for characterizing renal masses, especially for patients in whom iodinated CT contrast or gadolinium-based MRI contrast is contraindicated. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Dynamic 68Ga-PSMA-11 PET/CT for the Primary Evaluation of Localized Renal Mass: A Prospective Study

The potential role of prostate-specific membrane antigen (PSMA) PET/CT in non-prostate cancer tumors has shown promising results. We examined the performance of dynamic ⁶⁸Ga-PSMA-11 PET/CT (DPSMA) for the evaluation of localized renal mass. Methods: A prospective case series of patients with a newly diagnosed renal mass who were referred for surgery was examined. DPSMA was performed in a standardized manner before surgery. The final surgical histology served as the standard of reference. PSMA expression in the tumor vasculature was assessed and staining intensity was scored. Tracer uptake and PSMA expression were compared between benign and malignant tissue. Results: Of 29 enhancing renal masses evaluated in 27 patients, 24 (83%) were malignant lesions. The median SUV_mean of benign and malignant lesions was 2.3 (interquartile range [IQR], 2.2-2.7) and 6.8 (IQR, 4.2-10.1), respectively (P = 0.009). Median SUV_max of benign and malignant lesions was 3.8 (IQR, 3.3-4.5) and 9.4 (IQR, 5.4-15.8), respectively (P = 0.015). The median washout coefficient (K ₂) was significantly lower in malignant lesions than in benign lesions (0.17 vs. 0.70, P = 0.02). Positive PSMA staining was found in 20 of 24 malignant lesions and in 2 of 5 benign lesions (P = 0.04). Conclusion: This pilot study demonstrated DPSMA uptake and kinetics in localized renal masses. Increased ⁶⁸Ga-PSMA-11 tracer uptake and intratumoral retention correlate with PSMA expression in malignant renal tumors compared with benign renal masses, supporting further assessment of DPSMA as a potential tool for evaluating localized renal masses.

Evaluation, diagnosis and surveillance of renal masses in the setting of VHL disease

This brief report focuses on the evaluation and diagnosis of clinically localized renal masses in children and adults with Von Hippel-Lindau (VHL) disease. Counseling considerations pertinent to the urologists, medical oncologists, and multidisciplinary teams involved in the care of these patients are addressed. As practice patterns regarding the evaluation and management of VHL tumors can vary considerably, this report aims to provide guidance on some of the controversies associated with the diagnostic evaluation and initial management of localized renal masses in VHL patients.

The role of renal mass biopsy in the management of small renal masses – patterns of use and surgeon opinion

Aims:

Renal mass biopsy (RMB) is advocated to improve management of small renal masses, however there is concern about its clinical utility. This study aimed to elicit opinions about the role of RMB in small renal mass management from surgeons managing renal cell carcinomas (RCC), and examine the frequency of pre-treatment biopsy in those with RCC.

Methods:

All surgeons in two Australian states (Queensland: n = 59 and Victoria: n = 108) who performed nephrectomies for RCC in 2012/2013 were sent questionnaires to ascertain views about RMB. Response rates were 54% for Queensland surgeons and 38% for Victorian surgeons. We used medical records data from RCC patients to determine RMB frequency.

Results:

Most Queensland (81%) and Victorian (59%) surgeons indicated they rarely requested RMB; however 34% of Victorians reported often requesting RMB, compared with no Queensland surgeons. This was consistent with medical records data: 17.6% of Victorian patients with T1a tumours received RMB versus 6.7% of Queensland patients ( p < 0.001). Surgeons’ principal concerns regarding RMB related to sampling reliability (90%) and/or histopathological interpretation (76%).

Conclusions:

Most surgeons report infrequent use of RMB for small renal masses, however we observed practice variation. The principal reasons for infrequent use were concerns about sampling reliability and histopathological interpretation, which may be valid in regions with less access to interventional radiologists and uropathologists. Further evidence is required to define patient groups for whom biopsy results will alter management.

Level of evidence:

Not applicable for this multicentre audit.

Percutaneous Biopsy Tract Seeding in a Patient with Muscle-invasive Bladder Cancer

Percutaneous biopsy can be used for tissue diagnosis of bladder tumors when cystoscopy with transurethral resection is not possible. The largest known case series includes 15 patients with no reported complications and good concordance with surgical pathology. However, concern remains regarding exposure of nonurothelial surfaces to tumor cells, as there are rare documented cases of tumor seeding along nephrostomy and biopsy tracts in upper tract urothelial carcinoma (UC). We present the first documented human case of bladder cancer involvement of the omentum and peritoneum along a biopsy tract and review the use of percutaneous access for upper and lower tract UC.

Comprehensive assessment of the morbidity of renal mass biopsy: A population-based assessment of biopsy-related complications

INTRODUCTION

We sought to assess seven-day and 30-day complications following renal mass biopsy (RMB), including mortality, hospitalizations, emergency department (ED) visits, and operative and non-operative complications and compare these to rates in population-matched controls.

METHODS

We performed a population-based, matched, retrospective cohort study of patients undergoing RMB following consultation with a urologist and axial imaging from 2003-2015 in Ontario, Canada. Data on seven-day and 30-day rates of mortality, as well as operative and non operative complications after RMB were reported. The seven-day and 30-day rates of mortality, operative and non-operative interventions, hospitalizations, and ED visits were compared to matched controls using multivariable logistic regression.

RESULTS

Among 6840 patients who underwent RMB in the study period, 24 (0.4%) and 159 (2.3%) died within seven and 30 days of their biopsy, respectively. Seven- and 30-day operative intervention rates were 79 (1.2%) and 236 (3.4%), respectively. Seven- and 30-day non-operative intervention rates were 227 (3.3%) and 529 (7.7%), respectively. Thirty-day mortality (odds ratio [OR] 8.1, 95% confidence interval [CI] 5.1-13.0), hospitalizations (OR 12.6, 95% CI 10.6-15.2), and ED visits (OR 3.8, 95% CI 3.4-4.3) were more common among patients who underwent RMB than the matched controls (p<0.001 for each).

CONCLUSIONS

Patients undergoing RMB may have a small but non-negligible increased risk of mortality, hospital readmission, and ED visits compared to matched controls. However, limitations in the granularity of the dataset limits the strength of these conclusions. Further studies are needed to confirm our results. These risks should be discussed with patients for shared decision-making and considered in the risk/benefit tradeoff for the management of small renal masses.

Does renal tumor biopsies for small renal carcinoma increase the risk of upstaging on final surgery pathology report and the risk of recurrence?

BACKGROUND

Renal tumor biopsies (RTB) have been proposed as a means to diminish overtreatment of small renal masses. A potential concern of RTB is tumor seeding along the biopsy tract leading to worse clinical outcomes.

OBJECTIVES

To evaluate whether RTB was associated with greater upstaging to pT3a compared to patients without a biopsy and to determine if pathologic upstaging affects the risk of recurrence.

DESIGN, SETTING AND PARTICIPANTS

The Canadian Kidney Cancer information system was used to identify patients who underwent radical or partial nephrectomy for malignant renal tumors ≤ 4cm (cT1a) between January 1, 2011 and July 2, 2019.

INTERVENTION

RTB prior to nephrectomy or nephrectomy without biopsy.

OUTCOMES MEASUREMENTS AND STATISTICAL ANALYSIS

Upstaging to pT3a and cancer recurrence were compared between subjects that had a RTB compared to those who did not. A multivariable analysis was used to evaluate factors associated with disease upstaging and recurrence.

RESULTS AND LIMITATIONS

The cohort consisted of 1993 cT1a patients, followed for a median of 17.5 months. Of these patients, 502 (25%) had a preoperative RTB. There was no difference in the proportion with tumor upstaging to pT3a between patients that had RTB compared to those who did not (7.2% vs. 6.3%; P = 0.5). On multivariable analysis, RTB was not associated with pathological upstaging (Odds Ratio 0.90; 95% Confidence Interval 0.61-1.34) or recurrence (Odds Ratio 1.04; 95% Confidence Interval 0.57-1.89). The main limitation is that the study is underpowered to detect small differences between groups.

CONCLUSIONS

In this large, multi-institution cohort, RTB was not associated with increased risk of tumor upstaging or recurrence. Hence, tumor tract seeding, although possible, should not be a clinical deterrent to using RTBs as a means of personalizing renal masses management and diminishing overtreatment.

PATIENT SUMMARY

Recent evidence suggests that tumor seeding following RTB may be more common than initially perceived. Our results have demonstrated that RTB was not associated with an increased risk of tumor upstaging or disease recurrence.

Radiomics and Artificial Intelligence for Renal Mass Characterization

Radiomics allows for high throughput extraction of quantitative data from images. This is an area of active research as groups try to capture and quantify imaging parameters and convert these into descriptive phenotypes of organs or tumors. Texture analysis is one radiomics tool that extracts information about heterogeneity within a given region of interest. This is used with or without associated machine learning classifiers or a deep learning approach is applied to similar types of data. These tools have shown utility in characterizing renal masses, renal cell carcinoma, and assessing response to targeted therapeutic agents in metastatic renal cell carcinoma.

Imaging guided percutaneous renal biopsy: do it or not?

Since its first reported application, renal biopsy became an important part of the diagnostic algorithm, considered advantages and risks, to better manage therapeutic options. The biopsy can be performed with different techniques (open, laparoscopic, transjugular, transurethral and percutaneous). Currently, the percutaneous approach is the modality of choice. Percutaneous biopsy can be performed under CT or US guidance, but critical benefits and disadvantages have to be considered. Core needle biopsy is usually preferred to fine-needle aspiration because of the sample quality, usually obtaining multiple cores, especially in heterogeneous tumors. Principal complications are hematuria (1-10%), perinephric hematoma (10-90%), pneumothorax (0,6%), clinically significant pain (1,2%).

Evolving Role of Urologists in the Management of Advanced Renal Cell Carcinoma

Advanced renal cell carcinoma is not uncommon, but necessitates a multidisciplinary approach for optimal treatment. Targeted therapy has increased the likelihood of urologists managing patients in all disease stages. Neoadjuvant therapy is currently experimental. Systemic therapy for metastatic disease demonstrates survival benefits. The role of cytoreductive nephrectomy and adjuvant therapy is dependent on patient selection. Management of advanced renal cell carcinoma involves continued optimization of available agents and biomarker development. This article reviews the role of the urologist in medical and surgical therapies, including prognostication, management of locally advanced and metastatic disease, and provides the most recent clinical trial data.

Active surveillance of small renal masses

Most renal masses incidentally detected by cross-sectional images are benign, being mainly cysts, and if they are malignant, they are indolent in nature with limited metastatic potential. Enhanced renal masses less than 4 cm in size are known as small renal masses (SRMs), and their growth rate (GR) and the possibility of developing metastasis are extremely low. Delayed intervention of SRMs by closed and routine imaging follow-up known as active surveillance (AS) is now an option according to urological guidelines. Radiologists have a key position in AS management of SRMs even unifocal and multifocal (sporadic or associated with genetic syndromes) and also in the follow-up of complex renal cysts by Bosniak cyst classification system. Radiologists play a key role in the AS of both unifocal and multifocal (sporadic or associated with genetic syndromes) SRMs as well as in the follow-up of complex renal cysts using the Bosniak cyst classification system. Indeed, radiologists must determine which patients with SRMs or complex renal cysts can be included in AS, establish the follow-up radiological test algorithm to be used in different scenarios, perform measurements in follow-up tests, and decide when AS should be discontinued. The purpose of this article is to review the indications and management of AS in SRMs, especially focused on specific scenarios, such as complex renal cysts and multifocal renal tumors (sporadic or hereditary). In this work, the authors aimed to provide a thorough review of imaging in the context of active surveillance of renal masses.

The role of renal biopsy to improve small renal mass diagnosis and management: are there predictive factors for a higher detection rate? The first Italian study of 100 cases

BACKGROUND

Incidence of small renal masses (SRMs) has increased over the last decade: in order to reduce overtreatment of benign lesions, renal tumor biopsy (RTB) has been advocated. The primary aim of this study were to establish the rate of diagnostic biopsies and the concordance rate between RTB and surgical pathology with regard to tumor histology. The secondary aim was to identify what predictive factors are associated with an initial diagnostic biopsy.

METHODS

We retrospectively analyzed RTB performed in our center in patients with SRMs between 2015 and 2017. We assessed patient demographics and clinical status, lesion characteristics and procedural factors. The categorical variables were tested with the chi-square test. We used univariate and multivariate analysis to identify what factors are indicative of non-diagnostic biopsies. We used the SPSS statistics v. 23.

RESULTS

We performed a total of 100 RTBs to management 94 patients. The initial biopsy was diagnostic in 88 patients (67 malignant and 21 benign lesion). The six remaining patients had repeat biopsies, of which four were diagnostic. Complications rate was 5% prevalently local hematoma treated with surveillance. Agreement between biopsy and surgical histology was found in 94% of cases. On contingency analysis and on univariate and multivariate analysis, these factors (age, tumor size, exophytic location, and type of imaging used) were not predictive with diagnostic biopsy.

CONCLUSIONS

RTB for SRMs helps establish pre-treatment diagnosis, reduce overtreatment, with a low risk of complications and high diagnostic rate. In our experience, we did not find predictive factors more likely associated with a diagnostic biopsy.

[Concordances and predictors of biopsies in renal tumors]

AIM

Evaluate the concordance between the renal lesions biopsy's histology and the final histology of the surgical specimen according to histological subtype, and search for predictive factors of non-concordance.

MATERIAL

We performed a monocentric retrospective study that included 156 patients suffering from a renal tumor that benefited a lesion biopsy before surgical treatment. Sensibility and specificity of the renal lesion's biopsy for histological diagnostic of the different renal tumors where calculated.

RESULTS

One hundred and fifty-eight renal tumor biopsies were realized between 2001 and 2016. One hundred and forty-three renal cell carcinoma were found on the surgical piece, 135 were diagnosed on prior biopsy. Global concordance rate was 88%. For the establishment of the nuclear Fuhrmann grade, the concordance rate (low vs. high grade) was 72.9%. The cohort was divided into 2 groups according to the existence (group 1, n=139) or the absence (group 2, n=19) of concordance. Group 1 and 2 differed by the predominance of men in group 1 (66% vs. 37%, P=0.013), distance between the sinus and the tumor above 4mm (65% vs. 42%, P=0.05).

CONCLUSION

In renal tumor care, renal biopsy is a reliable testing. However, some factors most likely linked to the tumor anatomy (intra-sinusal tumor) and their histological composition were involved in the lack of non-contribution to the diagnosis.

LEVEL OF EVIDENCE

4.

Development and validation of CT imaging-based preoperative nomogram in the prediction of unfavorable high-grade small renal masses

PURPOSE

In recent years, there has been an increase in the incidence of small renal masses (SRMs) and nephrectomy was the standard management of this disease in the past. Currently, the use of active surveillance has been recommended as an alternative option in the case of some patients with SRMs due to its heterogenicity. However, limited studies focused on the regarding risk stratification. Therefore, in the current study, we developed a nomogram for the purpose of predicting the presence of high-grade SRMs on the basis of the patient information provided (clinical information, hematological indicators, and CT imaging data).

PATIENTS AND METHODS

A total of 329 patients (consisting of development and validation cohort) who had undergone nephrectomy for SRMs between January 2013 and May 2016 retrospectively were recruited for the present study. All preoperative information, including clinical predictors, hematological indicators, and CT predictors, were obtained. Lasso regression model was used for data dimension reduction and feature selection. Multivariable logistic regression analysis was applied for the establishment of the predicting model. The performance of the nomogram was assessed with respect to its calibration and discrimination properties and externally validated.

RESULTS

The predictors used in the assessment of the nomogram included tumor size, CT tumor contour, CT necrosis, CT tumor exophytic properties, and CT collecting system oppression. Based on these parameters, the nomogram was evaluated to have an effective discrimination and calibration ability, and the C-index was found to be 0.883 after internal validation and 0.887 following external validation.

CONCLUSION

Based on the aforementioned findings, it can be concluded that CT imaging-based preoperative nomogram is an effective predictor of SRMs and hence can be used in the preoperative evaluation of SRMs, due to its calibration and discrimination abilities.

[Epidemiology and diagnostic assessment of small renal masses]

BACKGROUND

The incidence of small renal masses has been rising over the last few decades. At the same time, mortality of renal cell carcinoma (RCC) is decreasing. These trends can be explained by the availability of improved therapeutic measures and the good prognosis of small renal masses (SRM) turning out to be histopathologically benign or of low malignancy in many cases.

OBJECTIVES

The aim of this article is to present epidemiology and diagnostic assessment of SRM.

MATERIALS AND METHODS

Statistics, basic research, guidelines.

RESULTS

The incidence of SRM is rising due to the widespread use of imaging techniques such as computed tomography (CT), magnetic resonance imaging (MRI), and contrast-enhanced ultrasound (CEUS). Sensitivity is excellent for CEUS and for CECT in the characterization of SRM, while good specificity values can be reached by MRI. For characterization of complex cystic renal masses, CEUS has good diagnostic accuracy.

CONCLUSIONS

Due to improved diagnostic possibilities, SRMs can be diagnosed in early asymptomatic stages. As SRM have a good prognosis and often are of low malignancy therapy, options should be carefully considered; especially in older patients, active surveillance should considered.

Collagen organization of renal cell carcinoma differs between low and high grade tumors

Background

The traditional pathologic grading for human renal cell carcinoma (RCC) has low concordance between biopsy and surgical specimen. There is a need to investigate adjunctive pathology technique that does not rely on the nuclear morphology that defines the traditional grading. Changes in collagen organization in the extracellular matrix have been linked to prognosis or grade in breast, ovarian, and pancreatic cancers, but collagen organization has never been correlated with RCC grade. In this study, we used Second Harmonic Generation (SHG) based imaging to quantify possible differences in collagen organization between high and low grades of human RCC.

Methods

A tissue microarray (TMA) was constructed from RCC tumor specimens. Each TMA core represents an individual patient. A 5 μm section from the TMA tissue was stained with standard hematoxylin and eosin (H&E). Bright field images of the H&E stained TMA were used to annotate representative RCC regions. In this study, 70 grade 1 cores and 51 grade 4 cores were imaged on a custom-built forward SHG microscope, and images were analyzed using established software tools to automatically extract and quantify collagen fibers for alignment and density assessment. A linear mixed-effects model with random intercepts to account for the within-patient correlation was created to compare grade 1 vs. grade 4 measurements and the statistical tests were two-sided.

Results

Both collagen density and alignment differed significantly between RCC grade 1 and RCC grade 4. Specifically, collagen fiber density was greater in grade 4 than in grade 1 RCC (p < 0.001). Collagen fibers were also more aligned in grade 4 compared to grade 1 (p < 0.001).

Conclusions

Collagen density and alignment were shown to be significantly higher in RCC grade 4 vs. grade 1. This technique of biopsy sampling by SHG could complement classical tumor grading approaches. Furthermore it might allow biopsies to be more clinically relevant by informing diagnostics. Future studies are required to investigate the functional role of collagen organization in RCC.

Small renal carcinoma: the "when" and "how" of operation, active surveillance, and ablation

Small, locally restricted renal cell carcinoma less than 4 cm in size should ideally be removed operatively by nephron-sparing tumour enucleation (partial kidney resection). In an increasingly elderly population, there is a growing trend toward parallel incidence of renal cell carcinoma and chronic renal insufficiency, with the latter's associated general comorbidities. Thus, for some patients, the risks of the anaesthesia and operation increase, while the advantage in terms of survival decreases. Transcutaneous radio-frequency ablation under local anaesthesia, transcutaneous afterloading high-dose-rate brachytherapy under local anaesthesia, and percutaneous stereotactic ablative radiotherapy may offer a less invasive alternative therapy. Active surveillance is to be regarded as no more than a controlled bridging up to definitive treatment (operation or ablation), while watchful waiting, on account of the lack of prognostic relevance and the symptomatology of renal cell carcinoma, with its comorbidity-related, clearly reduced life expectancy, does not involve any further diagnostic or therapeutic measures.

Imaging of Unusual Renal Tumors

PURPOSE OF REVIEW

Renal masses are a wide entity and a common finding in clinical practice. Detection of these masses has increased in the last years, yet mortality rates have slightly decreased.

RECENT FINDINGS

According to the World Health Organization classification, there are 8 types, 51 subtypes, and a lot more subsequent subclassifications of renal tumors. Histopathological analysis should always be assessed for final diagnosis of theses tumors. However, imaging can be an important diagnostic guidance. The most common diagnoses of renal tumor are clear cell carcinoma, papillary renal cell carcinoma, angiomyolipoma, and transitional cell carcinoma. Nonetheless, a considerable variety of particular tumors can arise from the kidney, challenging the expertise of radiologists and urologists on this subject. The awareness of these unusual entities is vital for professionals working at a complex medical facility with greater volume of patients. We hereby present uncommon renal tumors and its pathological and radiological features.

Diagnostic Yield and Complication Rate in Percutaneous Needle Biopsy of Renal Hilar Masses With Comparison With Renal Cortical Mass Biopsies in a Cohort of 195 Patients

OBJECTIVE

The objective of this study was to compare diagnostic yield and complication rate in needle biopsy (NB) of renal hilar and cortical masses.

MATERIALS AND METHODS

With institutional review board approval, we retrospectively studied 195 patients (120 men, 75 women; mean age ± SD, 67 ± 13 years old) who underwent ultrasound-guided renal mass NB between January 2013 and December 2017. Operator years of experience, biopsy technique (coaxial or successive), needle gauge (22-gauge fine-needle aspiration, 18-gauge core-needle, or both), number of passes, postprocedural complication, and histopathologic diagnoses were recorded. A radiologist who was blinded to histopathologic diagnoses recorded mass location (upper pole, interpolar region, lower pole) and percentage of hilar involvement. Comparisons were performed using independent t and chi-square tests.

RESULTS

Of the masses biopsied, 5.6% (11/195) were 100% hilar (mean hilar involvement, 20.8% ± 29.8%; range, 0-100%). Mean lesion size was 44 ± 27 mm (range, 12-157 mm). NB diagnosis was established in 84.6% (165/195) of masses, and 15.4% (30/195) of biopsies were inconclusive, with no association with size (p = 0.55) or percentage of hilar involvement (p = 0.756). In the purely hilar masses, diagnosis was established in 72.7% (8/11) compared with 85.3% (157/184) with any cortical involvement (p = 0.265). There was no association between diagnosis and operator years of experience, biopsy technique, needle gauge, or number of passes (p > 0.05). Bleeding occurred after biopsy in 7.7% (15/195) of cases, was associated with percentage of hilar involvement (39.3% ± 44.9% vs 19.3% ± 27.8%; p = 0.012), and was more common in purely hilar masses (36.4% [4/11] vs 5.6% [11/195]; p < 0.001). Complications were not associated with any other feature (p > 0.05).

CONCLUSION

Percutaneous biopsy of renal hilar masses is technically feasible with diagnostic yield similar to that of cortical masses but with postprocedural bleeding more often than what is seen with cortical masses.

Can quantitative CT texture analysis be used to differentiate subtypes of renal cell carcinoma?

AIM

To investigate whether computed tomography (CT) texture analysis (TA) can be used to differentiate non-clear-cell renal cell carcinoma (non-ccRCC) from clear-cell RCC (ccRCC) and classify non-ccRCC subtypes.

MATERIALS AND METHODS

One hundred ccRCC and 27 non-ccRCC (12 papillary and 15 chromophobe) were analysed. Texture parameters quantified from multiphasic CT images were compared for the objectives. Receiver operating characteristic (ROC) analysis was performed and the area under the ROC curve (AUC) was calculated. The optimal discriminative texture parameters were used to produce support vector machine (SVM) classifiers. Diagnostic accuracy and 10-fold cross-validation was performed.

RESULTS

Compared to ccRCC, non-ccRCC had significantly lower mean grey-level intensity (mean), standard deviation (SD), entropy, mean of positive pixels (MPP), and higher kurtosis (p<0.001). A model incorporating SD, entropy, MPP, and kurtosis produced an AUC of 0.94±0.03 with an accuracy of 87% (sensitivity=89%, specificity=92%) to identify non-ccRCC from ccRCC. Compared to chromophobe RCC, papillary RCC had significantly lower mean and MPP (p=0.002). A model incorporating SD, MPP, and skewness resulted in an AUC of 0.96±0.04 with an accuracy of 78% (sensitivity=87%, specificity=92%) to differentiate between papillary and chromophobe RCC.

CONCLUSION

CT TA could potentially be used as a less invasive tool to classify histological subtypes of RCC.

Evaluation of diagnostic accuracy and a practical algorithmic approach for the diagnosis of renal masses by FNA

BACKGROUND

The classification of renal neoplasms is essential for oncologic risk stratification and clinical management, and an accurate pretreatment pathologic diagnosis can provide useful guidance for active surveillance, minimally invasive ablative therapy, or surgical resection and can reduce the incidence of overtreatment. Previous studies evaluating the diagnostic accuracy of fine-needle aspiration (FNA) and core-needle biopsy (CNB) for renal masses are limited and show variable results.

METHODS

Two hundred forty-seven renal FNA cases with or without concurrent CNB performed and/or reviewed at the Stanford University School of Medicine over the course of 20 years were identified. Cytohistopathologic correlation was performed for 77 cases with subsequent resection specimens. All available case materials were reviewed, and select cases were worked up further and reclassified as necessary.

RESULTS

Cytohistopathologic correlation showed 96% diagnostic specificity and 83% sensitivity for renal FNA with or without concurrent CNB. Discordant cases were mostly attributed to sampling errors or suboptimal specimens (79%) and also included 2 non-renal cell carcinoma entities (1 case of angiomyolipoma and 1 case of a benign peripheral nerve sheath tumor) and 1 case involving misclassification of the renal cell carcinoma subtype.

CONCLUSIONS

There is considerable value in FNA/CNB for the initial diagnosis of renal masses because of the high diagnostic specificity and sensitivity. Sensitivity is predominantly dependent on sufficient sampling, and additional potential diagnostic pitfalls include nonepithelial and rare entities. Judicious use of ancillary techniques is encouraged, especially when one is presented with a limited specimen, and this article presents a practical algorithmic approach to the diagnosis of renal masses using salient morphologic features and results from ancillary studies. Fine-needle aspiration is an accurate method for the diagnosis of renal masses. A practical diagnostic algorithm, based on salient morphologic and ancillary findings, is presented.