Renal mass imaging modalities: does body mass index (BMI) matter?

PURPOSE

Accurate measurement of renal mass size is crucial in the management of renal cancer. With the burdensome cost of imaging yet its need for management, a better understanding of the variability among patients when determining mass size remains of urgent importance. Current guidelines on optimal imaging are limited, especially with respect to body mass index (BMI). The aim of this study is to discern which modalities accurately measure renal mass size and whether BMI influences such accuracy.

METHODS

A multi-institutional chart review was performed for adult patients undergoing partial or radical nephrectomy between 2018 and 2021, with 236 patients ultimately included. Patients were categorized by BMI (BMI 1: 18.5-24.9, BMI 2: 25-29.9, BMI 3: 30-34.9, and BMI 4: ≥ 35). The greatest mass lengths were compared between the pathology report and the following: computerized tomography (CT), renal ultrasound, and magnetic resonance imaging (MRI).

RESULTS

The difference between greatest length on CT with contrast and MRI were significantly different when compared to pathologic measurement. BMI groups 3 and 4 were found to have a significant difference in size estimates compared to BMI 2 for CT with contrast. No difference was found between size estimates by BMI group for any other imaging modality.

CONCLUSION

CT with contrast becomes less accurate at estimating mass size for patients with BMI > 30. While contrast-enhanced CT remains a vital imaging modality for tissue enhancement in the context of unknown renal masses, caution must be used for mass size estimation in the obese population.

Characterization of renal masses with MRI-based radiomics: assessment of inter-package and inter-observer reproducibility in a prospective pilot study

OBJECTIVES

To evaluate radiomics features' reproducibility using inter-package/inter-observer measurement analysis in renal masses (RMs) based on MRI and to employ machine learning (ML) models for RM characterization.

METHODS

32 Patients (23M/9F; age 61.8 ± 10.6 years) with RMs (25 renal cell carcinomas (RCC)/7 benign masses; mean size, 3.43 ± 1.73 cm) undergoing resection were prospectively recruited. All patients underwent 1.5 T MRI with T2-weighted (T2-WI), diffusion-weighted (DWI)/apparent diffusion coefficient (ADC), and pre-/post-contrast-enhanced T1-weighted imaging (T1-WI). RMs were manually segmented using volume of interest (VOI) on T2-WI, DWI/ADC, and T1-WI pre-/post-contrast imaging (1-min, 3-min post-injection) by two independent observers using two radiomics software packages for inter-package and inter-observer assessments of shape/histogram/texture features common to both packages (104 features; n = 26 patients). Intra-class correlation coefficients (ICCs) were calculated to assess inter-observer and inter-package reproducibility of radiomics measurements [good (ICC ≥ 0.8)/moderate (ICC = 0.5-0.8)/poor (ICC < 0.5)]. ML models were employed using reproducible features (between observers and packages, ICC > 0.8) to distinguish RCC from benign RM.

RESULTS

Inter-package comparisons demonstrated that radiomics features from T1-WI-post-contrast had the highest proportion of good/moderate ICCs (54.8-58.6% for T1-WI-1 min), while most features extracted from T2-WI, T1-WI-pre-contrast, and ADC exhibited poor ICCs. Inter-observer comparisons found that radiomics measurements from T1-WI pre/post-contrast and T2-WI had the greatest proportion of features with good/moderate ICCs (95.3-99.1% T1-WI-post-contrast 1-min), while ADC measurements yielded mostly poor ICCs. ML models generated an AUC of 0.71 [95% confidence interval = 0.67-0.75] for diagnosis of RCC vs. benign RM.

CONCLUSION

Radiomics features extracted from T1-WI-post-contrast demonstrated greater inter-package and inter-observer reproducibility compared to ADC, with fair accuracy for distinguishing RCC from benign RM.

CLINICAL RELEVANCE

Knowledge of reproducibility of MRI radiomics features obtained on renal masses will aid in future study design and may enhance the diagnostic utility of radiomics models for renal mass characterization.

Applicability of Bosniak 2019 for renal mass classification on portal venous phase at the era of spectral CT imaging using rapid kV-switching dual-energy CT

OBJECTIVES

To evaluate the applicability of Bosniak 2019 criteria on a monophasic portal venous phase using rapid kilovoltage-switching DECT (rsDECT).

MATERIALS AND METHODS

One hundred twenty-seven renal masses assessed on rsDECT were included, classified according to Bosniak 2019 classification using MRI as the reference standard. Using the portal venous phase, virtual monochromatic images at 40, 50, and 77 keV; virtual unenhanced (VUE) images; and iodine map images were reconstructed. Changes in attenuation values between VUE and 40 keV, 50 keV, and 77 keV measurements were computed and respectively defined as ∆HU40keV, ∆HU50keV, and ∆HU77keV. The values of ∆HU40keV, ∆HU50keV, and ∆HU77keV thresholds providing the optimal diagnostic performance for the detection of internal enhancement were determined using Youden index.

RESULTS

Population study included 25 solid renal masses (25/127, 20%) and 102 cystic renal masses (102/127, 80%). To differentiate solid to cystic masses, the specificity of the predefined 20 HU threshold reached 88% (95%CI: 82, 93) using ∆HU77keV and 21% (95%CI: 15, 28) using ∆HU40keV. The estimated optimal threshold of attenuation change was 19 HU on ∆HU77keV, 69 HU on ∆HU50eV, and 111 HU on ∆HU40eV. The rsDECT classification was highly similar to that of MRI for solid renal masses (23/25, 92%) and for Bosniak 1 masses (62/66, 94%). However, 2 hyperattenuating Bosniak 2 renal masses (2/26, 8%) were classified as solid renal masses on rsDECT.

CONCLUSION

DECT is a promising tool for Bosniak classification particularly to differentiate solid from Bosniak I-II cyst. However, known enhancement thresholds must be adapted especially to the energy level of virtual monochromatic reconstructions.

CLINICAL STATEMENT

DECT is a promising tool for Bosniak classification; however, known enhancement thresholds must be adapted according to the types of reconstructions used and especially to the energy level of virtual monochromatic reconstructions.

KEY POINTS

• To differentiate solid to cystic renal masses, predefined 20 HU threshold had a poor specificity using 40 keV virtual monochromatic images. • Most of Bosniak 1 masses according to MRI were also classified as Bosniak 1 on rapid kV-switching dual-energy CT (rsDECT). • Bosniak 2 hyperattenuating renal cysts mimicked solid lesion on rsDECT.

A case report of aggressive mixed epithelial and stromal tumor of the kidney with malignant transformation

Mixed epithelial and stromal tumor of the kidney (MESTK) is a rare benign kidney tumor. In rare cases, malignant transformation, such as sarcomatoid features indicates poor clinical outcomes. In this study, we will describe a 45 years old man with a diagnosis of MESTK with malignant transformation of the sarcomatoid component, after right radical nephrectomy. The patient underwent chemotherapy with adriamycin, ifosfamide, and granulocyte-colony stimulating factor (G-CSF). The radiological characteristics of MESTK can pose diagnostic challenges due to its non-unique radiological appearance. The presence of sarcomatoid transformation is a hallmark feature of malignant MESTK which can be very aggressive.

Primary extra hepatic hydatid cyst of the kidney: A case report

Human echinococcosis (hydatid disease) is highly endemic in Morocco and reemerging as a significant public health problem in this country. It is a cyclozoonotic infection introduced by Echinococcus granulosus, that can invade any organ in the human body. The liver is the mostly affected organ, which is the primary site of human infestation, followed by lungs. Renal involvement by hydatid disease is commonly secondary, occurring owing to primary cyst rupture or disseminated disease. Primary renal localization, often presented as solitary cysts with no visceral involvement, is uncommon even in endemic zone. Herein, a rare cause of renal mass due to an isolated hydatid cyst in a 56-year-old woman who presented with ambiguous left flank pain for the last 10 years. Findings imaging did not reveal any other localizations of hydatid disease. For this scolicidal effect and to prevent peritoneal seeding, the patient was placed on albendazole 400 mg. Three weeks later, the surgery was performed successfully with a left total nephrectomy.

The Role of 99mTc-Sestamibi Single-photon Emission Computed Tomography/Computed Tomography in the Diagnostic Pathway for Renal Masses: A Systematic Review and Meta-analysis

CONTEXT

The diagnostic accuracy of current imaging techniques in differentiating benign from malignant neoplasms in the case of indeterminate renal masses is still suboptimal.

OBJECTIVE

To evaluate the diagnostic accuracy of 99mTc-sestamibi (SestaMIBI) single-photon emission tomography computed tomography (SPECT)/CT in characterizing indeterminate renal masses by differentiating renal oncocytoma and hybrid oncocytic/chromophobe tumor (HOCT) from (1) all other renal lesions and (2) all malignant renal lesions. Secondary outcomes were: (1) benign versus malignant; (2) renal oncocytoma and HOCT versus clear cell (ccRCC) and papillary (pRCC) renal cell carcinoma; and (3) renal oncocytoma and HOCT versus chromophobe renal cell carcinoma (chRCC).

EVIDENCE ACQUISITION

A literature search was conducted up to November 2022 using the PubMed/MEDLINE, Embase, and Web of Science databases. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed to identify eligible studies. Studies included were prospective and retrospective cross-sectional studies in which SestaMIBI SPECT/CT findings were compared to histology after renal mass biopsy or surgery.

EVIDENCE SYNTHESIS

Overall, eight studies involving 489 patients with 501 renal masses met our inclusion criteria. The sensitivity and specificity of SestaMIBI SPECT/CT for renal oncocytoma and HOCT versus all other renal lesions were 89% (95% confidence interval [CI] 70-97%) and 89% (95% CI 86-92%), respectively. Notably, for renal oncocytoma and HOCT versus ccRCC and pRCC, SestaMIBI SPECT/CT showed specificity of 98% (95% CI 91-100%) and similar sensitivity. Owing to the relatively high risk of bias and the presence of heterogeneity among the studies included, the level of evidence is still low.

CONCLUSIONS

SestaMIBI SPECT/CT has good sensitivity and specificity in differentiating renal oncocytoma and HOCT from all other renal lesions, and in particular from those with more aggressive oncological behavior. Although these results are promising, further studies are needed to support the use of SestaMIBI SPECT/CT outside research trials.

PATIENT SUMMARY

A scan method called SestaMIBI SPECT/CT has promise for diagnosing whether kidney tumors are malignant or not. However, it should still be limited to research trials because the level of evidence from our review is low.

Isolated renal hydatid cyst

INTRODUCTION AND IMPORTANCE

Hydatid disease, is a parasitic disease caused by the larval stage of the cestode Echinococcus granulosus. The Liver and lungs are the commonly affected organs but rarely kidney can be affected. Patient with primary renal hydatid may present with nonspecific symptoms or may be diagnosed incidentally. Imaging and serology are useful for diagnosis. The best therapy is surgery.

CASE PRESENTATION

This case is reported to discuss a 35-year-old female presented with complaints of left side flank pain and swelling. The abdominal US and CECT show renal cyst, which was nonspecific. She underwent an open surgical exploration and cystectomy plus partial pericystectomy done. Post-operative serology test show Echinococcus IgG positive. Postoperatively, the patient had an uneventful recovery and discharged with Albendazole therapy for 8 weeks.

CLINICAL DISCUSSION

Renal hydatid cyst is rare, accounting for less than 2 to 3 % of all hydatid disease. Renal hydatid cysts can remain asymptomatic for many years and then can be discovered incidentally. The diagnosis and staging of renal hydatid cysts rely heavily on imaging and serology. Hydatid disease is primarily treated surgically.

CONCLUSION

A high index of suspicion should be maintained, especially in endemic areas, to ensure timely and accurate diagnosis of renal hydatid cyst. Surgical excision remains the treatment of choice, with appropriate preoperative and postoperative anthelminthic therapy. Long-term follow-up is crucial to monitor for recurrence and associated complications.

Evaluation of a multiparametric renal CT algorithm for diagnosis of clear-cell renal cell carcinoma among small (≤ 4 cm) solid renal masses

OBJECTIVE

To evaluate a recently proposed CT-based algorithm for diagnosis of clear-cell renal cell carcinoma (ccRCC) among small (≤ 4 cm) solid renal masses diagnosed by renal mass biopsy.

METHODS

This retrospective study included 51 small renal masses in 51 patients with renal-mass CT and biopsy between 2014 and 2021. Three radiologists independently evaluated corticomedullary phase CT for the following: heterogeneity and attenuation ratio (mass:renal cortex), which were used to inform the CT score (1-5). CT score ≥ 4 was considered positive for ccRCC. Diagnostic accuracy was calculated for each reader and overall using fixed effects logistic regression modelling.

RESULTS

There were 51% (26/51) ccRCC and 49% (25/51) other masses. For diagnosis of ccRCC, area under curve (AUC), sensitivity, specificity, and positive predictive value (PPV) were 0.69 (95% confidence interval 0.61-0.76), 78% (68-86%), 59% (46-71%), and 67% (54-79%), respectively. CT score ≤ 2 had a negative predictive value 97% (92-99%) to exclude diagnosis of ccRCC. For diagnosis of papillary renal cell carcinoma (pRCC), CT score ≤ 2, AUC, sensitivity, specificity, and PPV were 0.89 (0.81-0.98), 81% (58-94%), 98% (93-99%), and 85% (62-97%), respectively. Pooled inter-observer agreement for CT scoring was moderate (Fleiss weighted kappa = 0.52).

CONCLUSION

The CT scoring system for prediction of ccRCC was sensitive with a high negative predictive value and moderate agreement. The CT score is highly specific for diagnosis of pRCC.

CLINICAL RELEVANCE STATEMENT

The CT score algorithm may help guide renal mass biopsy decisions in clinical practice, with high sensitivity to identify clear-cell tumors for biopsy to establish diagnosis and grade and high specificity to avoid biopsy in papillary tumors.

KEY POINTS

• A CT score ≥ 4 had high sensitivity and negative predictive value for diagnosis of clear-cell renal cell carcinoma (RCC) among solid ≤ 4-cm renal masses. • A CT score ≤ 2 was highly specific for diagnosis of papillary RCC among solid ≤ 4-cm renal masses. • Inter-observer agreement for CT score was moderate.

A sheep in wolf's clothing; a case of renal leiomyoma masquerading as hereditary leiomyomatosis and renal cell carcinoma

Active surveillance has become a standard of care for the management of small renal masses. Decision to transition from surveillance to intervention relies on several factors including growth kinetics, histologic grade on biopsy and patient comorbidities. Management of renal masses in pregnancy presents a unique change when clinical triggers must be weighed with risk to fetus. We present the case of a third trimester patient with an enlarging and enhancing renal mass managed with robotic assisted laparoscopic partial nephrectomy. Histologic analysis was consistent with renal leiomyoma. Renal leiomyomas are a rare benign mesenchymal tumor influenced by changes in progesterone-estrogen axis.

Morbidity of elective surgery for localized renal masses among elderly patients: A contemporary multicenter study

BACKGROUND

The aging population and the incidence of renal cell carcinoma (RCC) are increasing worldwide. Over 25% of newly diagnosed LRM (localized renal masses) occur in patients over the eighth decade of life. The decision-making and treatment approach to LRM in this population represents a clinical dilemma due to inherited decreased functional reserve and competing mortality risks. Current literature reports conflicting evidence regarding age as a risk factor for worst surgical outcomes. As such, we aimed to evaluate the contemporary morbidity of elective surgery for LRM among elderly patients, focusing on intraoperative and postoperative complications.

METHODS

After Ethical Committee approval, we queried our prospectively maintained databases to identify patients with preoperative eGFR ≥60 ml/min/1.73 m [(David and Bloom, 2022) 22 and a normal contralateral kidney who underwent partial or radical nephrectomy (PN or RN) for a single cT1-T2N0M0 LRM between 1/2015-12/2021 at four high-volume European Academic Institutions. Patients were categorized by age groups: <50 yrs (young) vs. 50-75 (middle-aged) yrs vs.> 75 yrs (elderly). Postoperative complications were recorded according to Clavien-Dindo (CD) classification. The primary objectives were the proportion of patients experiencing intraoperative (IOC), any grade (AGC), and high-grade postoperative complications (HGC), defined as CD grade 3-5.

RESULTS

Overall, 2469/3076 (80.2%) patients met the inclusion criteria. Of these, 363 (14.7%) were young, 1682 (68.1%) were middle-aged, and 424 (17.2%) were elderly. Compared to middle-aged and young patients, elderly patients had a higher median Charlson Comorbidity Index (6 vs. 4 vs. 0, p < 0.01) and a higher proportion of cT1 renal mass (87.6% vs. 93.0% vs. 93.6%, p < 0.01). No differences among the study groups were found regarding surgical approach (open vs. minimally-invasive) and type of surgery (PN vs. RN). We found that older patients experienced similar IOC (4.5% vs. 4.2% vs. 3.3%, p = 0.7) and AGC (23.1% vs. 20.0% vs. 21.5%, p = 0.4) compared to middle-aged and young patients, respectively. Similarly, there were no significant differences in HGC between the study cohorts (0.7% vs. 1.4% vs. 1.7%, p = 0.8). At multivariable analysis, open approach and PN significantly predicted the occurrence of AGCs, while only the open surgical approach was associated with the occurrence of HGCs.

CONCLUSION

In kidney cancer tertiary referral centers, the risk of IOC and postoperative HGC after PN or RN for localized renal masses (LRM) is low, despite a non-negligible risk of AGC, especially in elderly patients. Further efforts should focus on identifying multidisciplinary strategies to select patients most likely to benefit from surgery among elderly candidates with LRMs and decrease the morbidity of surgery in this specific setting.

Open versus robot-assisted partial nephrectomy for highly complex renal masses: a meta-analysis of perioperitive and functional outcomes

Robot-assisted partial nephrectomy (RAPN) is increasingly being used for the complex surgical management of renal masses. The comparison of RAPN with open partial nephrectomy (OPN) has not yet led to a unified conclusion with regard to perioperative outcomes. To conduct a systematic review and meta-analysis of the literature on the perioperative outcomes of RAPN compared with OPN. We performed a systematic search in PubMed, Embase, Web of Science, and Cochrane Library database for randomized control trials (RCTs) and non-RCTs that compare OPN to RAPN. The primary outcomes included perioperative, functional and oncologic. The odds ratio (OR) and weighted mean difference (WMD) were applied for the comparison of dichotomous and continuous variables with 95% confidence intervals (CIs). Five studies, comprising 936 patients, were included in the meta-analysis. Our findings indicated that there were no significant differences in blood loss, minor complication rate, eGFR decline from baseline, positive surgical margin, and ischemia time between OPN and RAPN. However, RAPN was associated with a shorter hospital stay (WMD 1.64 days, 95% CI - 1.17 to 2.11; p < 0.00001), lower overall complication rate (OR 1.72, 95% CI 1.21-2.45; p < 0.002), lower transfusion rate (OR 2.64, 95% CI 1.39-5.02; p = 0.003) and lower major complication rate (OR 1.76, 95% CI 1.11-2.79; p < 0.02) compared to OPN. Additionally, the operation time for OPN was shorter than that for RAPN (WMD - 10.77 min, 95% CI - 18.49 to - 3.05, p = 0.006). In comparison with OPN, RAPN exhibits better results in terms of hospital stay, overall complications, blood transfusion rate, and major complications, with no significant difference in intraoperative blood loss, minor complications, PSM, ischemia time, and short-term postoperative eGFR decline. However, the operation time of OPN is slightly shorter than that of RAPN.

Evidence based Urology: The Gist Leading Us to the Evidence for Decisions

Making clinical decisions based on guideline recommendations that include relevant information and stakeholder perspectives requires a systematic approach that is transparent and clear. The evidence-to-decision framework helps clinicians, panel members, and policymakers to translate knowledge into patient care.

Sequential liquid-based cytology based on exfoliative cells of 18-gauge core needle groove to improve renal mass core needle biopsy yield: a real-world observational study

Background

Renal mass biopsy (RMB) has regained clinical interest in recent years due to the pursuit of individualized and precision medicine. Renal mass core needle biopsy (RMCNB) for histopathology (HP), with or without liquid-based cytology (LBC), has been used increasingly in our hospital. This study investigated factors influencing the HP diagnostic yield of RMCNB, and compared the diagnostic rate between HP alone and HP plus LBC.

Methods

In this retrospective cross-sectional study, a total of 134 patients who underwent ultrasound-guided percutaneous RMCNB in the National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College between January 2015 and May 2022 were enrolled. All biopsies were performed using an 18-gauge core needle biopsy gun, and the sampling tissues and exfoliative cells of 18-gauge core needle groove were delivered for HP and LBC diagnosis, respectively. The patient demographics, clinical indications, tumor characteristics, number of biopsies, final pathological diagnosis, and follow-up data were reviewed. Univariate and multivariate logistic regression analyses were performed to evaluate the association between variables and HP diagnostic yield of RMCNB. The diagnostic rate between HP and HP plus LBC was compared using McNemar's test and agreement was evaluated using the Kappa score.

Results

The most common indication of RMCNB was renal masses with a radiological diagnosis of locally advanced disease or distant metastasis (86.6%). The HP diagnostic yield was established in 88.1% (118/134) of cases, and the diagnostic rate of HP plus LBC was 94.0% (126/134). Logistic regression analyses revealed that non-enhanced area exceeding 50% [odds ratio (OR): 0.021, 95% confidence interval (CI): 0.003-0.134, P<0.001] and number of core biopsies (OR: 9.479, 95% CI: 1.528-58.794, P=0.016) were associated with the HP diagnostic yield of RMCNB. The diagnostic rate of HP plus LBC was significantly higher than that of HP alone (94.0% vs. 88.1%, P=0.008), and they showed substantial agreement (Kappa =0.638, P<0.001). Meanwhile, in the non-enhanced area ≥50% subgroup, the diagnostic rate between HP plus LBC and HP alone was significantly different (86.7% vs. 60%, P=0.008), and the agreement was fair (Kappa =0.375, P=0.009).

Conclusions

RMCNB has a high diagnostic yield with a minimum of two high-quality core biopsies, LBC can improve the diagnostic yield of HP alone, especially in masses with large non-enhanced area.

Update on the Role of Imaging in Staging of Common Pediatric Abdominal Tumors

Neuroblastoma, Wilms tumor, and hepatoblastoma are the most common pediatric abdominal malignancies. Management of these diseases is a multidisciplinary process that continues to evolve based on the results of international collaborative trials and advances in understanding of tumor biology. Each of these tumors has unique characteristics and behavior which are reflected in their respective staging systems. It is important for clinicians involved in the care of children with abdominal malignancies to be familiar with current staging guidelines and imaging recommendations. This article reviews the current role of imaging in the management of these common pediatric abdominal malignancies, with emphasis on initial staging.

New-onset Chronic Kidney Disease After Surgery for Localised Renal Masses in Patients with Two Kidneys and Preserved Renal Function: A Contemporary Multicentre Study

Background

There is a lack of evidence on acute kidney injury (AKI) and new-onset chronic kidney disease (CKD) after surgery for localised renal masses (LRMs) in patients with two kidneys and preserved baseline renal function.

Objective

To evaluate the prevalence and risk of AKI and new-onset clinically significant CKD (csCKD) in patients with a single renal mass and preserved renal function after being treated with partial (PN) or radical (RN) nephrectomy.

Design setting and participants

We queried our prospectively maintained databases to identify patients with a preoperative estimated glomerular filtration rate (eGFR) of ≥60 ml/min/1.73 m² and a normal contralateral kidney who underwent PN or RN for a single LRM (cT1-T2N0M0) between January 2015 and December 2021 at four high-volume academic institutions.

Intervention

PN or RN.

Outcome measurements and statistical analysis

The outcomes of this study were AKI at hospital discharge and the risk of new-onset csCKD, defined as eGFR <45 ml/min/1.73 m², during the follow-up. Kaplan-Meier curves were used to examine csCKD-free survival according to tumour complexity. A Multivariable logistic regression analysis assessed the predictors of AKI, while a multivariable Cox regression analysis assessed the predictors of csCKD. Sensitivity analyses were performed in patients who underwent PN.

Results and limitations

Overall, 2469/3076 (80%) patients met the inclusion criteria. At hospital discharge, 371/2469 (15%) developed AKI (8.7% vs 14% vs 31% in patients with low- vs intermediate- vs high-complexity tumours, p < 0.001). At the multivariable analysis, body mass index, history of hypertension, tumour complexity, and RN significantly predicted the occurrence of AKI. Among 1389 (56%) patients with complete follow-up data, 80 events of csCKD were recorded. The estimated csCKD-free survival rates were 97%, 93% and 86% at 12, 36, and 60 mo, respectively, with significant differences between patients with high- versus low-complexity and high- versus intermediate-complexity tumours (p = 0.014 and p = 0.038, respectively). At the Cox regression analysis, age-adjusted Charlson Comorbidity Index, preoperative eGFR, tumour complexity, and RN significantly predicted the risk of csCKD during the follow-up. The results were similar in the PN cohort. The main limitation of the study was the lack of data on eGFR trajectories within the 1st year after surgery and on long-term functional outcomes.

Conclusions

The risk of AKI and de novo csCKD in elective patients with an LRM and preserved baseline renal function is not clinically negligible, especially in those with higher-complexity tumours. While baseline nonmodifiable patient/tumour-related characteristics modulate this risk, PN should be prioritised over RN to maximise nephron preservation if oncological outcomes are not jeopardised.

Patient summary

In this study, we evaluated how many patients with a localised renal mass and two functioning kidneys, who were candidates for surgery at four referral European centres, experienced acute kidney injury at hospital discharge and significant renal functional impairment during the follow-up. We found that the risk of acute kidney injury and clinically significant chronic kidney disease in this patient population is not negligible, and was associated with specific baseline patient comorbidities, preoperative renal function, tumour anatomical complexity, and surgery-related factors, in particular the performance of radical nephrectomy.

The Changing Role of Renal Mass Biopsy

The incidence and prevalence of small renal masses (SRMs) continues to rise and with increased detection comes increases in surgical management, although the probability of an SRM being benign is upward of 30%. An extirpative treatment first diagnose-later strategy persists and clinical tools for risk stratification such as renal mass biopsy remain severely underutilized. The overtreatment of SRMs has multiple detrimental effects including surgical complications, psychosocial stress, financial loss, and reduced renal function leading to downstream effects such as the need for dialysis and cardiovascular disease.

A giant metanephric adenoma in a young male

Metanephric adenoma is an uncommon renal tumor with almost exclusively benign behavior, which can clinically and radiologically imitate malignancy. The histological examination is therefore crucial in diagnosis. Herein, we report a case of an 18-year-old male with a huge left renal mass. Histopathology and immunohistochemistry of nephrectomy resection specimen confirmed it to be metanephric adenoma. We present our experience with this rare tumor entity and literature review with focusing on differential diagnosis.

Perioperative therapeutic plasma exchange in a patient with rare Factor XIII inhibitor

INTRODUCTION

Factor XIII deficiency is a rare bleeding disorder which could be severe if inherited or less severe if acquired. We report a case of acquired Factor XIII inhibitor in a 75-year-old male with a suspicious left renal mass treated perioperatively with therapeutic plasma exchange (TPE).

PATIENT AND METHOD

To perform kidney biopsy and ablation of the renal mass, six daily TPE treatments were performed before and after biopsy to minimize bleeding risk because the patient did not respond to drug therapy. Both thromboelastography (TEG) and laboratory-based coagulation tests were performed to assess coagulation status prior to and after TPE.

RESULTS

The biopsy indicated oncocytoma which was removed by surgical procedure. Factor XIII activity remained below 15 % throughout TPE treatments, but Factor XIII inhibitor titer reduced from initial positive value of 1:40 to negative following the third TPE and remained negative through the sixth TPE. Unfortunately, the inhibitor titer was positive at 1:20 in the fifth month and 1:5 in the sixth month during follow-up.

CONCLUSIONS

TPE is useful in removing XIII inhibitory factor, but the effects are only short term.

Comprehensive Management of Renal Masses in Solitary Kidneys

BACKGROUND

A renal mass in a solitary kidney (RMSK) has traditionally been managed with partial nephrectomy (PN), although radical nephrectomy (RN) is occasionally required. Most RMSK studies have focused on patients for whom PN was achieved.

OBJECTIVE

To provide a comprehensive analysis of the management strategies/outcomes for an RMSK and address knowledge deficits regarding this challenging disorder.

DESIGN, SETTING, AND PARTICIPANTS

A total of 1024 patients diagnosed with an RMSK (1975-2022) were retrospectively evaluated. Baseline characteristics and pathologic/functional/survival outcomes were analyzed.

INTERVENTION

PN/RN/cryoablation (CA)/active surveillance (AS).

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Functional outcomes, perioperative morbidity/mortality, and 5-yr recurrence-free survival (RFS) were evaluated. Kruskal-Wallis and chi-square tests were used to compare cohorts, and log-rank test and Cox proportional hazard model were used for survival analysis.

RESULTS AND LIMITATIONS

Of 1024 patients, 842 underwent PN (82%), 102 CA (10%), 54 RN (5%), and 26 AS (3%). The median tumor size and RENAL([R]adius [tumor size as maximal diameter], [E]xophytic/endophytic properties of tumor, [N]earness of tumor deepest portion to collecting system or sinus, [A]nterior [a]/posterior [p] descriptor, and [L]ocation relative to polar lines) score were 3.7 cm and 8, respectively. The median follow-up was 53 mo. For PN, 95% were clamped, and the median warm and cold ischemia times were 22 and 45 min, respectively. For PN, the median preoperative glomerular filtration rate (GFR) was 57 ml/min/1.73 m², and the median new baseline and 5-yr GFRs were 47 and 48 ml/min/1.73 m², respectively. Dialysis-free survival for PN was 97% at 5 yr. Twenty-two (2.1%) patients with clear-cell renal cell carcinoma and RENAL score ≥10 (median = 11) received tyrosine kinase inhibitors (TKIs) to facilitate PN, leading to 57% median decrease of tumor volume; PN was accomplished in 20 (91%). Forty-one patients had planned RN (4.0%), most often due to severe pre-existing chronic kidney disease (CKD), and 13 were converted from PN to RN (1.5%). Clavien III-V perioperative complications were observed in 80 (8%) patients and 90-d mortality was 0.6%. Five-year RFS for PN, CA, and RN were 83%, 80%, and 72%, respectively (p = 0.03 for PN vs RN).

CONCLUSIONS

Nephron-sparing approaches are feasible and successful in most RMSK patients. PN for an RMSK is often challenging but can be facilitated by selective use of TKIs. RN is occasionally required due to severe CKD, over-riding oncologic concerns, or conversion from PN. This is the first large RMSK study to provide a comprehensive analysis of all management strategies/outcomes.

PATIENT SUMMARY

Kidney cancer in a solitary kidney is a major challenge for achieving cancer-free status and avoiding dialysis. Although partial nephrectomy is the principal treatment for a renal mass in a solitary kidney, other options are occasionally required to optimize outcomes.

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.

Percutaneous thermal ablation for cT1 renal mass in solitary kidney: A multicenter trifecta comparative analysis versus robot-assisted partial nephrectomy

INTRODUCTION

Renal cell carcinoma (RCC) in solitary kidney (SK) represents a challenging scenario. We sought to compare outcomes of robot-assisted partial nephrectomy (RAPN) versus percutaneous thermal ablation (PTA) in SK patients with renal tumors cT1.

MATERIALS AND METHODS

We performed a multicenter retrospective analysis of SK patients treated for RCC. The PTA group included cryoablation or radiofrequency ablation. We collected baseline characteristics, intraoperative, pathological, and post-operative data. We applied an arbitrary composite "trifecta" to assess surgical, functional, and oncological outcomes, only for malignant histology. RFS analysis was performed using the Kaplan-Meier method. Multivariable regression analysis was performed to determine independent predictors of "trifecta" achievement.

RESULTS

We included 198 SK patients (RAPN, n = 50; PTA n = 119). Mean clinical tumor size was not significantly different while R.E.N.A.L. score was higher for RAPN (p < 0.001). No differences in intra and major post-procedural complications. Recurrence rate was higher in PTA group but not statistically significant (p < 0.328). No difference in metastasis rate was found (p = 0.435). RFS was 96.1% in RAPN and 86.8% in PTA cohort (p = 0.003) while no difference in PFS was detected (p = 0.1). Trifecta was achieved in 72.5% of RAPN vs 77.3% of PTA (p = 0.481). Multivariable analysis has not detected predictors for Trifecta achievement.

CONCLUSION

PTA offers good outcomes in the management of SK patients with RCC. Compared with RAPN, it might carry a higher risk of recurrence; on the other hand, re-treatment is possible. Overall, PTA can be safely offered to treat SK patients presenting RCC. In general, it should be preferred in more frail patients to minimize the risk of complications.

Granulomatosis with polyangiitis presenting as multiple renal masses: A case report with MRI findings

It is extremely rare for granulomatosis with polyangiitis to form masses in the kidneys. Magnetic resonance imaging findings of renal masses caused by this disease have been infrequently reported. In this study, we report a case of renal masses caused by granulomatosis with polyangiitis with different findings. While on steroid treatment for a recently diagnosed granulomatosis with polyangiitis, a man in his 60s underwent computed tomography for a hepatic dysfunction. Computed tomography showed incidental findings of a 40 mm × 35 mm mass in the left kidney and two 8 mm × 8 mm masses in the right kidney; all masses were hypovascular. On magnetic resonance imaging, the left renal mass showed a hyperintense signal with slightly hypointense signal rim on T2-weighted imaging. The left renal mass showed a strong hypointense signal where the mass abutted the renal capsule. On diffusion-weighted imaging, the left renal mass showed an isointense signal with a hyperintense signal rim. Both right renal masses showed an isointense signal with slightly hypointense signal rim on T2-weighted imaging and hyperintense signal on diffusion-weighted imaging. Suspecting renal masses caused by the disease, the patient was then treated with steroids and methotrexate. After 6 months of treatment, both right renal masses resolved; however, the left renal mass shrank but abnormal signal remained. Based on the treatment course, it is conceivable that the renal masses were caused by granulomatosis with polyangiitis.

Estimating Postoperative Renal Function After Surgery for Nonmetastatic Renal Masses: A Systematic Review of Available Prediction Models

CONTEXT

A variety of models predicting postoperative renal function following surgery for nonmetastatic renal tumors have been reported, but their validity and clinical usefulness have not been formally assessed.

OBJECTIVE

To summarize prediction models available for estimation of mid- to long-term (>3 mo) postoperative renal function after partial nephrectomy (PN) or radical nephrectomy (RN) for nonmetastatic renal masses that include only preoperative or modifiable intraoperative variables.

EVIDENCE ACQUISITION

A systematic review of the English-language literature was conducted using the MEDLINE, Embase, and Web of Science databases from January 2000 to March 2022 according to the PRISMA guidelines (PROSPERO ID: CRD42022303492). Risk of bias was assessed according to the Prediction Model Study Risk of Bias Assessment Tool.

EVIDENCE SYNTHESIS

Overall, 21 prediction models from 18 studies were included (nine for PN only; eight for RN only; four for PN or RN). Most studies relied on retrospective patient cohorts and had a high risk of bias and high concern regarding the overall applicability of the proposed model. Patient-, kidney-, surgery-, tumor-, and provider-related factors were included among the predictors in 95%, 86%, 100%, 61%, and 0% of the models, respectively. All but one model included both patient age and preoperative renal function, while only a few took into account patient gender, race, comorbidities, tumor size/complexity, and surgical approach. There was significant heterogeneity in both the model building strategy and the performance metrics reported. Five studies reported external validation of six models, while three assessed their clinical usefulness using decision curve analysis.

CONCLUSIONS

Several models are available for predicting postoperative renal function after kidney cancer surgery. Most of these are not ready for routine clinical practice, while a few have been externally validated and might be of value for patients and clinicians.

PATIENT SUMMARY

We reviewed the tools available for predicting kidney function after partial or total surgical removal of a kidney for nonmetastatic cancer. Most of the models include patient and kidney characteristics such as age, comorbidities, and preoperative kidney function, and a few also include tumor characteristics and intraoperative variables. Some models have been validated by additional research groups and appear promising for improving counseling for patients with nonmetastatic cancer who are candidates for surgery.

Partial Versus Radical Nephrectomy: Complexity of Decision-Making and Utility of AUA Guidelines

INTRODUCTION

The American-Urological-Association(AUA) Guidelines for renal cancer(2017) recommend consideration for radical-nephrectomy(RN) over partial(PN) whenever there is increased oncologic-risk; and RN should be prioritized if three other criteria are all also met: 1) increased tumor-complexity; 2) no preexisting chronic-kidney-disease/ proteinuria, and 3) normal contralateral kidney that will likely provide estimated glomerular-filtration-rate (eGFR) >45ml/min/1.73m² even if RN is performed. Our objective was to assess the complexity of decision-making about RN/PN and utility of AUA Guidelines statements regarding this issue.

PATIENTS AND METHODS

Retrospective review of 267 consecutive RN/PN from 2019(100-RN/167-PN). High tumor-complexity was defined as R.E.N.A.L.≥9. Increased oncologic-risk was defined as tumor >7cm, locally-advanced or infiltrative-features on imaging, or high-risk pathology on biopsy, if obtained. New-baseline GFR after RN was estimated using global-GFR, split-renal-function_{contralateral}, and presuming 25% renal-functional-compensation.

RESULTS

163 patients(61%) fit scenarios that are well-defined in the Guidelines. Of these, 34 had strong indications for RN, and all had RN. Twelve of 129 patients(9.3%) underwent RN despite Guidelines generally favoring PN. The remaining 104 patients(39%) did not fit within situations where the Guidelines provide specific recommendations. In these patients, RN was often performed despite functional-considerations favoring PN due to overriding concerns about oncologic-risk and/or tumor-complexity.

CONCLUSION

Our data demonstrate complexity of decision-making about PN/RN as almost 40% of patients did not fit well-described AUA Guidelines descriptors. Compliance was generally strong although occasional overutilization of RN remains a concern in our series, and will be addressed with additional education. Further studies will be required to assess the generalizability of our findings in other institutions/settings.

Does size matter? Comparing robotic versus open radical nephrectomy for very large renal masses

INTRODUCTION

We evaluated perioperative and mortality outcomes of robotic-assisted radical nephrectomy (RRN) vs. open radical nephrectomy (ORN) for very large renal cell carcinomas (RCC).

MATERIALS AND METHODS

Adult patients with non-metastatic RCC >10 cm in size (pT2b) were identified from the National Cancer Database (2010-2017). Mixed-effects multivariable logistic regression adjusting for patient, tumor, and facility characteristics were used to evaluate rates of positive margin, prolonged length of stay (LOS) (>75th percentile), 30-day readmission, and 30-day and 90-day mortality for RRN vs. ORN. Overall survival (OS) was evaluated using the Kaplan-Meier method and adjusted Cox proportional hazard modeling.

RESULTS

Of the 2,977 patients who underwent radical nephrectomy, 492 (16.5%) underwent RRN. Factors associated with RRN included male gender, metro or urban locations, academic facilities, Charlson-Deyo score >2, private or Medicaid insurance, and surgery in a later year (all P < 0.05). Tumors ≥15.1cm in size were associated with a higher rate of conversion to open surgery (P < 0.001). ORN was associated with increased median postoperative LOS (4d [interquartile range; IQR 3-6] vs. 3d, [IQR 2-4]; P < 0.01). RRN demonstrated no significant difference in the risk of positive margin, 30-day readmission, 30-day mortality, or 90-day mortality. RRN was associated with a decreased risk of prolonged LOS (OR 0.38; 95%CI [0.28-0.53]). There was no difference in long-term OS observed in patients treated with ORN vs. RRN.

CONCLUSIONS

Very large, non-metastatic RCC can be safely and effectively treated with RRN. Rates of conversion to open were higher for tumors ≥15.1 cm. RRN has comparable long-term OS and improved LOS compared to ORN.

Attenuation values on virtual unenhanced images obtained with detector-based dual-energy computed tomography: observations on single- and split-bolus contrast protocols

PURPOSE

To compare virtual unenhanced (VUE) attenuation values and their agreement with true unenhanced (TUE) images in patients who underwent dual-layer detector-based dual-energy computed tomography (dlDECT) with single- vs. split-bolus contrast media protocol.

METHODS

In this HIPAA-compliant, IRB-approved retrospective analysis, a total of 105 patients who underwent nephrographic phase (NP) dlDECT between 07/2018 and 11/2019 were included: 55 patients received single bolus and 50 patients split-bolus examinations. Both scan protocols comprised a TUE and 120-kVp NP acquisition from which VUE images were reconstructed. A radiologist performed ROI-based attenuation measurements of liver parenchyma, main portal vein, aorta, spleen, renal parenchyma, and pelvis on TUE and VUE images. Agreement between TUE and VUE images was determined and compared for both protocols and each anatomic region.

RESULTS

VUE attenuation was significantly higher than TUE attenuation in both cohorts in the liver, portal vein, spleen, and renal parenchyma (p < 0.05), while it was similar in the abdominal aorta in both cohorts (p = 0.05, 0.7522, respectively). VUE attenuation was significantly higher than TUE attenuation in the renal pelvis of the split-bolus cohort (p < 0.05). When comparing VUE images between single- and split-bolus protocols, the renal parenchyma yielded a significantly higher VUE attenuation in the single-bolus cohort (single bolus: 38.8 ± 3.3 HU vs. split bolus: 36.8 ± 3.6 HU; p < 0.05), whereas the split-bolus cohort revealed markedly higher VUE attenuation in the renal pelvis (single bolus: 2.3 ± 10.8 HU vs. split bolus: 92.3 ± 76.8; p < 0.05). Mean intra-patient differences between TUE and VUE images were comparable between single- and split-bolus cohorts (p-range 0.09-0.35) except for the renal parenchyma and pelvis: in the first, the single-bolus cohort yielded a higher VUE attenuation, while in the second, attenuation was significantly higher in the split-bolus cohort (p < 0.05).

CONCLUSION

VUE attenuation overestimated TUE attenuation and differed between split- and single-bolus protocols for the renal parenchyma and pelvis, while all other tissues showed comparable VUE attenuation.

Surgical Management of Synchronous, Bilateral Renal Masses: A 1-decade Referral Center Experience

BACKGROUND

Management and decision-making in patients with bilateral renal masses are controversial.

OBJECTIVE

To report our experience of surgical management in patients with bilateral renal masses undergoing surgery at a high-volume center.

DESIGN, SETTING, AND PARTICIPANTS

We retrospectively collected data from patients treated with partial nephrectomy (PN) or radical nephrectomy for bilateral renal masses at a single referral institution between June 2008 and June 2019. Patient- and tumor-related features, timing (one vs two stage), and surgical approach (open vs robotic) were analyzed.

SURGICAL PROCEDURE

A one- versus two-stage strategy was adopted according to the opportunity to perform at least one PN using a clampless or selective-clamping approach, in order to avoid acute kidney injury.

MEASUREMENTS

Operative time, warm ischemia time, and intra- and postoperative complications were recorded. Histopathological results and tumor histology were assessed.

RESULTS AND LIMITATIONS

Overall, 41 patients were included. The median age was 67 yr and the median preoperative estimated glomerular filtration rate (eGFR) was 84 ml/min/1.73 m². The median Preoperative Aspects and Dimensions Used for an Anatomical (PADUA) score was 8 (interquartile range [IQR] 7-8) for both sides. In 17 (42%) patients, a simultaneous approach was chosen, with a pure robotic approach in 11/17 cases, while among the 24 (58.6%) patients treated with a two-stage strategy, 15 (62.5%) were treated with a robotic approach on both sides. Intraoperative complications and postoperative major (CDC ≥3) complications were recorded in 7.3% and 4.9% of cases, respectively. The overall positive surgical margins rate was 2.4%. At a median follow-up of 42 (IQR 18-59) mo, the median eGFR was 73 (IQR 64-80) ml/min/1.73 m², while disease-free survival and cancer-specific mortality were 90.2% and 7.3%, respectively.

CONCLUSIONS

Our experience underlines that both simultaneous and staged surgical treatment of patients with bilateral renal masses are feasible and safe if grounded on proper patient selection.

PATIENT SUMMARY

Management of patients with bilateral renal masses is challenging, given the heterogeneity of clinical scenarios and the need to optimize the timing of treatment to achieve maximal functional preservation while ensuring oncological efficacy.

Recent advances in imaging techniques of renal masses

Multiphasic multidetector computed tomography (CT) forms the mainstay for the characterization of renal masses whereas magnetic resonance imaging (MRI) acts as a problem-solving tool in some cases. However, a few of the renal masses remain indeterminate even after evaluation by conventional imaging methods. To overcome the deficiency in current imaging techniques, advanced imaging methods have been devised and are being tested. This review will cover the role of contrast-enhanced ultrasonography, shear wave elastography, dual-energy CT, perfusion CT, MR perfusion, diffusion-weighted MRI, blood oxygen level-dependent MRI, MR spectroscopy, positron emission tomography (PET)/prostate-specific membrane antigen-PET in the characterization of renal masses.

Small renal mass with large lymph nodal metastasis and inferior vena cava thrombus: an exceptional amalgamation

A small renal mass is defined as a tumour <4cm. The standard treatment of choice for small renal masses is partial or radical nephrectomy, depending on the tumour anatomy, and has good overall and cancer-specific survival. Its association with lymph node metastasis and inferior vena cava (IVC) thrombus is very uncommon. We describe a case of a right small renal mass with a large metastatic paracaval lymph node with IVC level I thrombus who was treated with right radical nephrectomy with thrombus removal and lymph node excision.

Pediatric metanephric adenoma with Fanconi-Bickel syndrome: a case report and review of literature

Background

Metanephric adenoma (MA) is a rare benign renal tumor that resembles renal cell carcinoma and Wilms’ tumor in radiological as well as pathological appearance. It can present at any age or gender, and it is extremely rare in the pediatric age group with less than 50 reported cases. Fanconi–Bickel syndrome (FBS) is a rare autosomal recessive disorder of carbohydrate metabolism. Herein, we report a rare incidence of MA in a boy with a genetically confirmed FBS who underwent a nephron-sparing surgery.

Case presentation

A 21-month-old boy was referred to the pediatric urology clinic for further evaluation of an incidentally discovered left renal mass. His laboratory investigations showed normal renal function, hypophosphatemia, high blood glucose level, markedly elevated serum alkaline phosphatase, and low serum vitamin D. Blood picture showed signs of polycythemia and urinalysis showed glucosuria and aminoaciduria. Genetic testing was positive for Fanconi–Bickel syndrome. Radiological investigations were carried out with abdominal ultrasound and computerized tomography (CT) with intravenous contrast documented a sharply marginated peripheral hypoechoic hypovascular homogeneously enhancing mass at the upper pole of the left kidney measuring 2.0 × 1.8 × 2.0 cm. The child was admitted and started on supportive treatment until his medical condition was stabilized, then underwent elective open left partial nephrectomy via a left upper transverse abdominal transperitoneal incision. The excised renal mass was sent for histopathological assessment and was found to be a tumor composed of tightly packed tubules with no mitotic figures or necrosis and scanty cytoplasm consistent with MA. After good hydration and tumor resection, his polycythemia gradually improved. The patient was discharged home in a good condition with his proper replacement therapies. His follow-up abdominal ultrasound after 12 months showed no signs of recurrence.

Conclusions

Metanephric adenoma is extremely rare in the pediatric age group, especially in those who have a FBS. The only way to diagnose and treat this tumor is by surgical resection as most patients are asymptomatic. A nephron-sparing surgery is better for this age group in which the future renal function is considered.

Use of lumason/sonovue in contrast-enhanced ultrasound of the kidney for characterization of renal masses-a meta-analysis

Indeterminate renal masses are a common clinical problem. CEUS has several advantages to characterize both cystic and solid renal masses including thin slice thickness, excellent background subtraction, and real-time imaging with a high frame rate. The ultrasound contrast agents are not nephrotoxic and can be used in patients with renal insufficiency and obstruction. The Bosniak classification has been developed for use in CT and MRI. A CEUS Bosniak classification has not yet been developed. This meta-analysis reviews the results of renal mass characterization using Lumason/Sonovue in characterizing renal solid and cystic masses. For complex cystic renal lesions (419 patients; 436 lesions), the pooled sensitivity and specificity of CEUS were 95% (95% CI: 91%, 99%) and 84% (95% CI: 77%, 90%) and for solid lesions (331 patients; 341 lesions), the pooled sensitivity and specificity of CEUS were 98% (95% CI: 95%, 100%) and 78% (95% CI: 68%, 88%), respectively.

Renal Mass Biopsy

Kidney cancer accounts for 2% of cancer related deaths. Historically, a patient with a solid renal mass would undergo surgery without biopsy given the previously low diagnostic yield of biopsy and the fear of tumor seeding. This led to a high rate of resection for benign masses. With the rising incidence of renal masses discovered on imaging, improvements in biopsy technique and advancements in pathologic evaluation of biopsy samples of renal masses, renal mass biopsy now plays an important role in selected patients with renal masses. Coaxial core needle biopsy is the preferred technique with a low rate of complications and a high diagnostic yield. This article will discuss indications, methods, utility, limitations and complications of renal mass biopsy.

Simplified PADUA renal (SPARE) nephrometry score validation and long-term outcomes after robot-assisted partial nephrectomy

BACKGROUND

International guidelines suggest the use of anatomic scores to predict surgical outcomes after partial nephrectomy (PN). We aimed at validating the use of Simplified PADUA Renal (SPARE) nephrometry score in robot-assisted PN (RAPN).

MATERIALS AND METHODS

Three hundred and sixty-eight consecutive RAPN patients were included. Primary endpoints were overall complications, postoperative acute kidney injury (AKI) and TRIFECTA achievement. Secondary endpoint was estimated glomerular filtration rate (eGFR) decrease at last follow-up. Multivariable logistic and linear regression models were used.

RESULTS

Of 368 patients, 229 (62%) vs. 116 (31%) vs. 23 (6.2%) harboured low- vs. intermediate- vs. high-risk renal mass, according to SPARE classification. SPARE score predicted higher risk of overall complications (Odds ratio [OR]: 1.23, 95%CI 1.09-1.39; P < 0.001), and postoperative AKI (OR: 1.20, 95%CI 1.08-1.35; P < 0.01). Moreover, SPARE score was associated with lower TRIFECTA achievement (OR: 0.89, 95%CI 0.81-0.98; P = 0.02). Predicted accuracy was 0.643, 0.614 and 0.613, respectively. After a median follow-up of 40 (IQR: 21-66) months, eGFR decrease ranged from -7% in low-risk to -17% in high-risk SPARE.

CONCLUSIONS

SPARE scoring system predicts surgical success in RAPN patients. Moreover, SPARE score is associated with eGFR decrease at long-term follow-up. Thus, the adoption of SPARE score to objectively assess tumor complexity prior to RAPN may be preferable.

Nephrolithiasis associated with embolization material, Lipiodol®, following embolization of large renal angiomyolipoma

Angiomyolipoma (AML) is a benign renal mass that can be treated with nephron sparing surgery or transarterial embolization. Embolization has been favored due to efficacy and safety profile. This case demonstrates a previously undocumented phenomenon of AML treated with transarterial embolization using Lipiodol® (Guerbet LLC, Princeton, NJ) resulting in nephrolithiasis and retention of Lipiodol® two years after original embolization. Although Lipiodol®-based embolization has not been shown to cause nephrolithiasis, it may have been the nidus for stone formation, and this is an important potential complication worthy of further study.

Repeat Percutaneous Radiofrequency Ablation of T1 Renal Cell Carcinomas is Safe in Patients with Von Hippel-Lindau Disease

Purpose

Patients with Von Hippel-Lindau disease often develop multifocal, metachronous renal cell carcinomas which require therapy. The purpose of this retrospective single-center study is to evaluate the outcomes of radiofrequency ablation (RFA) in the treatment of renal cell carcinomas in patients with Von Hippel-Lindau disease.

Materials and Methods

9 patients (4 male, 5 female, 47.9 ± 10.7 y/o) with Von Hippel-Lindau disease underwent 18 CT-guided percutaneous RFA procedures for the treatment 21 renal cell carcinomas (largest diameter: 32.9 ± 8.6 mm, cT1a: 16, cT1b: 5). Seven patients were previously treated either by partial or radical nephrectomy. Technical success, effectiveness, safety, progression-free survival, overall survival and tumor characteristics were analyzed.

Results

All RFA procedures were technically successful without major complications. There were 5 minor complications. No residual or recurrent tumor was seen in the ablation zone during a follow-up of 34.0 ± 18.1 months (0–58 months). No patient required dialysis during follow-up. One patient died after 63 months after the first treatment due to complications from a cerebellar hemangioblastoma. No endpoint was reached for overall or progression-free survival.

Conclusions

The results from this limited case series suggest that RFA of RCCs in patients with VHL is a safe and effective therapy, which can preserve sufficient renal function even after renal surgery.

The increasing use of renal tumor biopsy amongst Canadian urologists: When is biopsy most utilized?

INTRODUCTION

The role of renal tumor biopsy (RTB) in the management of small renal masses (SRMs) is progressively being recognized as a tool to decrease overtreatment. While an increasing number of studies assessing its role in diagnostics are becoming available, RTB remains variably used amongst urologists. Many patient-, tumor-, and institution-related factors may influence urologists on whether to perform a RTB to help guide management.

OBJECTIVE

We aimed at identifying factors associated with the use of RTB for localized SRMs within a number of centers contributing data to the Canadian Kidney Cancer information system.

MATERIAL AND METHODS

We identified 3,838 patients diagnosed with a localized SRM (≤4 cm) between January 2011 and December 2018. Patients were stratified based on whether a RTB was performed prior to the primary therapeutic intervention. Factors associated with use of RTB were assessed using univariable and multivariable logistic regression models.

RESULTS

A total of 993 patients (25.9%) underwent an RTB. There was an overall increase in RTB use over time (P < 0.001), with patients diagnosed between 2015 and 2018 undergoing more RTB than patients diagnosed between 2011 and 2014 (29.8% vs. 22.2%, respectively; P < 0.001). Patients managed in centers with the highest patient-volume had RTB more frequently than patients managed in low-volume centers. On multivariable analysis, increasing year of diagnosis was significantly associated with more RTB use. Patients treated with surgery underwent RTB statistically less often than patients undergoing thermal ablation (P < 0.001) or managed with active surveillance (P < 0.001). Larger SRMs were associated with more RTB use in patients on active surveillance (P = 0.009), but with less RTB in patients undergoing surgery (P = 0.045).

CONCLUSION

This large multicenter cohort study reveals an increasing adoption and overall use of RTB amongst Canadian urologists. Patients managed in high-volume centers and those undergoing non-surgical management were associated with greater use of RTB. Tumor size was also associated with RTB use. This study highlights the influence that physician perceptions and clinical factors may have in the decision to use RTB prior to initiating a therapeutic approach.

EZR-ROS1 fusion renal cell carcinoma mimicking urothelial carcinoma: report of a previously undescribed gene fusion in renal cell carcinoma

A subset of renal cell carcinomas harbor gene fusions, and we report the first case of an EZR-ROS1 fusion in renal cell carcinoma. A 47-year-old female presented with hematuria and a mass involving the renal pelvis. Renal biopsy revealed a tumor with solid and tubular architecture that was diffusely positive for PAX8, CK7, and vimentin; retained expression of INI1; focally positive for P504S; and negative for GATA3 and TFE3. Partial nephrectomy was performed, and histologically, the tumor had solid and tubular architecture with mucin-like content within tubules. The nuclei corresponded to WHO/ISUP grade 2 and 3. The morphology was neither specific nor diagnostic, and a final diagnosis of unclassified renal cell carcinoma with solid and tubular architecture was rendered. Molecular sequencing revealed an EZR-ROS1 fusion: a fusion that has never been reported in renal cell carcinoma. Recognition of this fusion is of significance if the tumor becomes metastatic as treatment with crizotinib may be considered.

Very low risk T1a renal cell carcinoma presenting with pathological fracture caused by a solitary metastases to the contralateral arm

BACKGROUND

Renal Cell Carcinomas are notorious for asynchronous metastases, atypical metastatic sites and late relapses even decades after nephrectomy. It is quite rare though for RCCs to present as metastatic, solitary and symptomatic bone lesions. Even more uncommon is a solitary bone metastasis much larger that the primary tumour caused by a low risk primary T1a RCC which would have otherwise been eligible for active surveillance.

CASE PRESENTATION

An otherwise healthy 68-year-old female was seen by the orthopaedics for right shoulder and upper arm worsening pain. Imaging showed a pathological fracture caused by a 5.5 cm lytic lesion involving the coracoid process and proximal humerus. She underwent proximal humeral replacement and histology of the lesion showed metastatic RCC. Whole body CT scan revealed a primary tumour of the left kidney less than 4cm in diameter. The patient underwent laparoscopic radical nephrectomy and diagnosis of a T1a, clear cell RCC without adverse pathological features was confirmed. She has been on systematic therapy with oral TKIs since and is free from recurrence at 12-months follow up.

CONCLUSIONS

Even T1a RCCs without adverse pathological features can give rise to distant metastases following unpredictable patterns of spread thereby questioning the safety of active surveillance in healthy and fit patients.

Visceral fat is associated with high-grade complications in patients undergoing minimally invasive partial nephrectomy for small renal masses

Introduction:

Minimally invasive partial nephrectomy is standard of care treatment for small renal masses.

Objective:

We evaluated the relationship between subcutaneous and visceral obesity with high-grade postoperative 30-day complications in patients undergoing minimally invasive partial nephrectomy.

Methods:

We retrospectively identified 98 patients at our institution from 2014 to 2017 who underwent laparoscopic or robotic-assisted partial nephrectomy due to suspected renal cell carcinoma. Patients were stratified based on presence or absence of high-grade (Clavien ≥ IIIa) 30-day postoperative complications. Means were compared with the independent t test and proportions with chi-square analysis. Multivariate logistic regression was performed to determine independent predictors of high-grade 30-day complications.

Results:

Mean nephrometry score was 6.7 with 21 (21.4%) patients having hilar tumors. Mean estimation of blood loss was 207 mL, mean operating time was 223 min, and mean warm ischemia time was 23 min. The majority of patients had clear renal cell carcinoma (n = 83, 84.7%) and pT1a disease (n = 76, 77.6%) with negative margins (n = 89, 90.8%) on pathology. There were 5 (5.1%) patients who experienced a high-grade postoperative 30-day complication. Mean visceral fat index was an independent predictor of high-grade 30-day complications (odds ratio: 1.02; 95% confidence interval: 1.002–1.03; p = 0.027).

Conclusions:

Visceral obesity should be considered as a prognostic indicator of outcomes in patients undergoing surgical treatment for a small renal mass.

Diagnostic renal mass biopsy is associated with individual categories of PADUA and RENAL nephrometry scores: Analysis of diagnostic and concordance rates with surgical resection

BACKGROUND

Renal mass biopsy (RMB) is a safe and accurate method for diagnosis and clinical management of renal masses. However, the non-diagnostic rate is a limiting factor. We tested the hypothesis that imaging characteristics and anatomic complexity of the mass may impact RMB diagnostic outcome using the preoperative aspects and dimensions used for an anatomical (PADUA) classification and radius-exophytic/endophytic-nearness-anterior/posterior-location (RENAL) score.

MATERIAL AND METHODS

Single institution, retrospective study of 490 renal masses from 443 patients collected from 2001 to 2018. Outcome measurements include (1) diagnostic and concordance rates amongst RMB types and RMB with surgical resection specimens; (2) association between diagnostic RMB and anatomical complexity of renal masses. The analysis was conducted in unselected masses and small renal masses (SRMs).

RESULTS

RMB was performed by fine needle aspiration (FNA), core needle biopsy (CNB), or both (FNA+CNB). Non-diagnostic rate was significantly higher for FNA compared to CNB and FNA+CNB in both unselected and SRMs. Subset analysis in the FNA+CNB group showed similar diagnostic rates for FNA and CNB. In unselected masses, specificity for FNA, CNB, and FNA+CNB was 100%. Sensitivity was higher for CNB (90.1%, P = 0.002) and FNA+CNB (96.3%, P = 0.004) compared to FNA (66.7%). For unselected masses, endophytic growth predicted a non-diagnostic CNB. R.E.N.A.L location entirely between the polar lines (central) and entirely above the upper polar line predicted a diagnostic CNB. Sonography-guidance predicted a diagnostic FNA. For SRMs, non-diagnostic CNB was associated with endophytic growth, while diagnostic CNB was associated with renal sinus invasion and operator experience. More cystic masses were sampled by FNA, but diagnostic results were similar for FNA and CNB.

CONCLUSIONS

Endophytic growth consistently predicted a non-diagnostic CNB in unselected and SRMs, whereas sonography-guidance predicted a diagnostic FNA. Cystic masses could be adequately sampled by FNA.

Selective Suturing or Sutureless Technique in Robot-assisted Partial Nephrectomy: Results from a Propensity-score Matched Analysis

BACKGROUND

Despite efforts aimed at preserving renal function, the functional decline after robot-assisted partial nephrectomy (RAPN) is not negligible. To address the risk of intraparenchymal vessel injuries during renorrhaphy, with consequent loss of functional renal parenchyma, we introduced a new surgical technique for RAPN.

OBJECTIVE

To compare perioperative patient outcomes between selective-suturing or sutureless RAPN (suRAPN) and standard RAPN (stRAPN).

DESIGN, SETTING, AND PARTICIPANTS

Ninety-two consecutive patients undergoing RAPN for a renal mass performed by a high-volume surgeon at a European tertiary center were included. Propensity-score matching was used to account for baseline differences between suRAPN and stRAPN patients.

INTERVENTION

RAPN using a selective-suturing or sutureless technique versus standard RAPN.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Perioperative outcomes included operative time, blood loss, length of stay, and intraoperative and 30-d postoperative complications. We also evaluated trifecta achievement (warm ischemia time ≤25 min, negative surgical margins, and no perioperative complications) and the incidence of postoperative acute kidney injury (AKI). We applied χ² tests, t tests, and Kruskal-Wallis tests to assess differences in perioperative outcomes between suRAPN and stRAPN.

RESULTS AND LIMITATIONS

Overall, 29 patients (31%) were treated with suRAPN. Only one suRAPN patient experienced intraoperative complications (p = 0.9). Two suRAPN patients (6.9%) and four stRAPN patients (13.8%) experienced 30-d postoperative complications (p = 0.3). Operative time (110 vs 150 min; p < 0.01) and length of stay (2 vs 3 d; p = 0.02) were shorter for suRAPN than for stRAPN. The trifecta outcome was achieved in 25 suRAPN patients (86%) and 20 stRAPN patients (70%; p = 0.1). Only one suRAPN patient (3.4%) versus five stRAPN patients (17%) experienced postoperative AKI (p = 0.2). Finally, the decrease in the estimated glomerular filtration rate at 6-mo follow-up was lower in the suRAPN (-5.2%) than in the stRAPN group (-9.1%; p < 0.01). Lack of randomization represents the main study limitation.

CONCLUSIONS

A selective-suturing or sutureless technique in RAPN is feasible and safe. Moreover, suRAPN is a lower-impact surgical procedure. We obtained promising results for trifecta and functional outcomes, but prospective randomized trials are needed to validate the impact of selective suturing or a sutureless technique on long-term functional outcomes.

PATIENT SUMMARY

We assessed a new technique in robotic surgery to remove part of the kidney because of kidney cancer. Our new technique involves selective suturing or no suturing of the area from where the tumor is removed. We found that the rate of complications did not increase and the operating time and length of hospital stay were shorter using this new technique.

Renal schwannoma: A case report and literature review of a rare and benign entity mimicking an invasive renal neoplasm

Schwannomas of the kidney are rare with only a handful of cases reported in literature. We present a case of a large Schwannoma of the right kidney causing mass effect with imaging characteristics thought to represent renal cell carcinoma. On imaging, these masses present similarly to solid renal masses and are therefore indistinguishable without tissue diagnosis. Thus, surgical resection is the definitive treatment for renal schwannomas.

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Schwannoma of the kidney is a rare entity.

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Schwannoma of the kidney presents similarly to renal cell carcinoma on imaging.

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Schwannoma of the kidney can present as large renal masses exerting mass effect.

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Surgical resection is indicated to confirm diagnosis of Schwannoma of the kidney or renal cell carcinoma.

Lexicon for renal mass terms at CT and MRI: a consensus of the society of abdominal radiology disease-focused panel on renal cell carcinoma

PURPOSE

There is substantial variation in the radiologic terms used to characterize renal masses, leading to ambiguity and inconsistency in clinical radiology reports and research studies. The purpose of this study was to develop a standardized lexicon to describe renal masses at CT and MRI.

MATERIALS AND METHODS

This multi-institutional, prospective, quality improvement project was exempt from IRB oversight. Thirteen radiologists belonging to the Society of Abdominal Radiology (SAR) disease-focused panel on renal cell carcinoma representing nine academic institutions participated in a modified Delphi process to create a lexicon of terms used to describe imaging features of renal masses at CT and MRI. In the first round, members voted on terms to be included and proposed definitions; subsequent voting rounds and a teleconference established consensus. One non-voting member developed the questionnaire and consolidated responses. Consensus was defined as ≥ 80% agreement.

RESULTS

Of 37 proposed terms, 6 had consensus to be excluded. Consensus for inclusion was reached for 30 of 31 terms (13/14 basic imaging terms, 8/8 CT terms, 6/6 MRI terms and 3/3 miscellaneous terms). Despite substantial initial disagreement about definitions of 'renal mass,' 'necrosis,' 'fat,' and 'restricted diffusion' in the first round, consensus for all was eventually reached. Disagreement remained for the definition of 'solid mass.'

CONCLUSIONS

A modified Delphi method produced a lexicon of preferred terms and definitions to be used in the description of renal masses at CT and MRI. This lexicon should improve clarity and consistency of radiology reports and research related to renal masses.

Radiologic features of mixed epithelial and stromal tumors of the kidney: Hyperattenuating on unenhanced computed tomography and T2-hypointensity on magnetic resonance imaging

In the 2016 World Health Organization renal tumor classification, the mixed epithelial and stromal tumor family was introduced as a new entity. This family encompasses a spectrum of tumors, ranging from predominantly cystic tumors (adult cystic nephromas) to tumors that are variably solid (mixed epithelial and stromal tumors). The majority of previous studies incorporating “mixed epithelial and stromal tumor” in the titles were actually reports of imaging findings of adult cystic nephroma. Thus, the solid component of mixed epithelial and stromal tumors has not been well evaluated. In this study, we present 2 cases of mixed epithelial and stromal tumors, as defined by the 2016 World Health Organization classification, showing a predominantly solid component. The characteristic findings of the solid component of these tumors were T2-hypointensity on magnetic resonance imaging and hyperattenuation on unenhanced computed tomography. Angiomyolipoma with epithelial cysts and epithelioid angiomyolipoma should be considered in the differential diagnosis of mixed epithelial and stromal tumors.

Three cases of BRAF mutation negative Erdheim-Chester disease with a challenging distinction from IgG4-related disease

Background

Erdheim-Chester disease (ECD) is a rare non-Langerhans histiocytosis with slow progression over the years that is particularly difficult to diagnose.

Cases

Here we report three cases of ECD without BRAF mutation presenting with a renal mass, hairy kidney appearance, and a rather benign course, for which the diagnosis of ECD was delayed, characterized by multiple investigations and unsuccessful treatments attempts. In two cases the distinction from IgG4-related disease required multiple investigations and reevaluation of the clinical, radiological, histological, and immunological characteristics.

Conclusion

A correct diagnosis of ECD may take several years and often requires revisiting previous hypotheses. Reassessment of histological slides and more modern complementary exams such as PET-CT or BRAF and MAPK-ERK mutation analysis can help to confirm the diagnosis of ECD and to select effective therapy.

Comparison of image quality of subtracted and nonsubtracted breath hold VIBE and free breathing GRASP in the evaluation of renal masses

OBJECTIVE

To compare the image quality of subtracted and nonsubtracted images obtained using volumetric interpolated breath-hold exam (VIBE) and free breathing T1 weighted Golden-angle Radial Sparse Parallel (GRASP).

METHODS

We retrospectively evaluated 27 consecutive patients who underwent MRI for the evaluation of renal masses. Contrast enhanced VIBE and free breathing GRASP imaging were performed, and subtraction images generated. Two radiologists performed quantitative and qualitative evaluations of image quality of nonsubtracted and subtracted data sets. Statistical analysis was performed using the Wilcoxon signed-rank test, paired t-test and kappa statistics.

RESULTS

VIBE images scored statistically higher for the following parameters in the coronal and axial plane: sharpness, streak artifact, image noise, and overall image quality for standard and subtracted images (all P values P < 0.001). GRASP images had significantly less subtraction artifact in the coronal (P = 0.042) plane with a similar trend in the axial plane (P = 0.079). Interreader Kappa values for qualitative images scores were fair to good (0.23-0.71). Quantitative subtracted GRASP images had significant less subtraction artifact compared to VIBE in the anterior-posterior (3.9 mm SD 2.6 mm versus 5.8 mm SD 3.6 mm, P = 0.010), and craniocaudal direction (4.4 mm SD 2.9 mm versus 7.0 mm SD 5.3 mm, P = 0.010); a trend was seen in the left-right direction (2.6 mm SD 1.4 mm versus 4.0 mm SD 3.9 mm, P = 0.084).

CONCLUSION

VIBE images have significantly better image quality than free breathing GRASP images, however free breathing GRASP images have significantly less subtraction artifact.

Incidental squamous cell carcinoma of renal pelvis presenting as skin invasion: a case report

Introduction

Squamous cell carcinoma of the renal pelvis is a rare neoplasm, accounting for less than 0.8% of malignant renal tumors. Chronic irritation is believed to be the primary pathogenic cause for squamous cell carcinoma of the renal pelvis. The most frequently reported cases of squamous cell carcinoma of the renal pelvis generally present with hydronephrosis, pyelonephritis, or nephrolithiasis. The skin of the flank is a very uncommon site of clinical presentation. Here, we report an exceedingly rare case of squamous cell carcinoma of the renal pelvis presenting as skin invasion of the flank.

Case presentation

A 66-year-old Han Chinese man consulted our hospital because of a right lumbar skin lesion lasting more than 3 months. His physical examination revealed that he had a palpable mass about 6.0 cm × 5.0 cm in size at the posterior axillary line in the right low back with skin ulceration 3 mm in diameter and exudation on it. Magnetic resonance imaging showed hydronephrosis of the right kidney and plaque-like abnormal signal in the middle portion of the kidney. The patient underwent a right nephrectomy. The sinus tract formation between the ulcerative skin in the right low back and the middle portion of the right kidney could be found. The distended kidney could not be excised entirely for tight adhesion. Pathological examination showed moderately differentiated renal squamous cell carcinoma with invasion of the renal parenchyma and perirenal adipose tissue.

Conclusion

It is extremely rare for renal squamous cell carcinoma to present as skin invasion. Recurrent percutaneous nephrolithotomy may be a risk factor for squamous cell carcinoma of the renal pelvis. The possibility of renal squamous cell carcinoma should be kept in mind in patients who have hydronephrosis, nephrolithiasis, or chronic pyelonephritis for a long time or with renal anomalies. More radiological examinations are suggested for such patients.

Medical treatment for an isolated renal multilocular hydatid cyst in an elderly: a case report

BACKGROUND

Almost all cases of renal hydatid cysts need surgical intervention for treatment. We report a case of isolated renal hydatid cyst treated successfully only with medical therapy.

CASE PRESENTATION

This case is a 79-year-old veterinarian presented with right flank pain, hydatiduria and positive echinococcus granulosus serology. A 70*50 mm cyst with daughter cysts in mid-portion of right kidney on presentation was changed into a 60*40 mm cyst without daughter cysts at last follow-up. Due to patient's refusal of surgery, our patient received medical treatment including praziquantel and albendazole. After completion of first round of treatment, recurrence occurred and the same treatment was repeated. At last, the cyst became inactive and calcified with negative serology and no clinical symptoms under medical treatment.

CONCLUSION

The treatment of choice in renal hydatid cyst is surgery; although there are some reports about the efficacy of medical treatments for hydatid cysts but lower rates of recurrence and higher efficacy put surgery in a superior position compared to medical approaches. Our case showed relative success of medical treatment, despite the presence of a large multilocular renal involvement. Thus, medical therapy without surgery can be considered in very particular cases with isolated renal hydatid cysts.

Prediction of Benign and Malignant Solid Renal Masses: Machine Learning-Based CT Texture Analysis

RATIONALE AND OBJECTIVES

This study aimed to investigate whether benign and malignant renal solid masses could be distinguished through machine learning (ML)-based computed tomography (CT) texture analysis.

MATERIALS AND METHODS

Seventy-nine patients with 84 solid renal masses (21 benign; 63 malignant) from a single center were included in this retrospective study. Malignant masses included common renal cell carcinoma (RCC) subtypes: clear cell RCC, papillary cell RCC, and chromophobe RCC. Benign masses are represented by oncocytomas and fat-poor angiomyolipomas. Following preprocessing steps, a total of 271 texture features were extracted from unenhanced and contrast-enhanced CT images. Dimension reduction was done with a reliability analysis and then with a feature selection algorithm. A nested-approach was used for feature selection, model optimization, and validation. Eight ML algorithms were used for the classifications: decision tree, locally weighted learning, k-nearest neighbors, naive Bayes, logistic regression, support vector machine, neural network, and random forest.

RESULTS

The number of features with good reproducibility was 198 for unenhanced CT and 244 for contrast-enhanced CT. Random forest algorithm demonstrated the best predictive performance using five selected contrast-enhanced CT texture features. The accuracy and area under the curve metrics were 90.5% and 0.915, respectively. Having eliminated the highly collinear features from the analysis, the accuracy and area under the curve values slightly increased to 91.7% and 0.916, respectively.

CONCLUSION

ML-based contrast-enhanced CT texture analysis might be a potential method for distinguishing benign and malignant solid renal masses with satisfactory performance.

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.