Small renal mass biopsy - how, what and when: report from an international consensus panel

Automatic renal carcinoma biopsy guidance using forward-viewing endoscopic optical coherence tomography and deep learning

Percutaneous renal biopsy is commonly used for kidney cancer diagnosis. However, the biopsy procedure remains challenging in sampling accuracy. Here we introduce a forward-viewing optical coherence tomography probe for differentiating tumor and normal tissues, aiming at precise biopsy guidance. Totally, ten human kidney samples, nine of which had malignant renal carcinoma and one had benign oncocytoma, were used for system evaluation. Based on their distinct imaging features, carcinoma could be efficiently distinguished from normal renal tissues. Additionally, oncocytoma could be differentiated from carcinoma. We developed convolutional neural networks for tissue recognition. Compared to the conventional attenuation coefficient method, convolutional neural network models provided more accurate carcinoma predictions. These models reached a tissue recognition accuracy of 99.1% on a hold-out set of four kidney samples. Furthermore, they could efficiently distinguish oncocytoma from carcinoma. In conclusion, our convolutional neural network-aided endoscopic imaging platform could enhance carcinoma diagnosis during percutaneous renal biopsy procedures.

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.

Ablation of Kidney Tumors in Patients with Substantial Kidney Impairment: Current Status

PURPOSE OF REVIEW

To review the current status of kidney tumor ablation in patients with substantial kidney impairment.

RECENT FINDINGS

Few reports of kidney tumor ablation in such patients have recently been published. The reported prevalence of patients with stage 4 or 5 chronic kidney disease (CKD) among patients undergoing ablation is 2.0%-10%. In patients with stage 4 or 5 CKD, local tumor control rates were 88%-100%. The effect of ablation on CKD stage is unclear, and the observed deteriorations in kidney function are consistent with both the effect of cryoablation and the natural course of advanced CKD. According to guidelines, active surveillance may be selected. The goals of treatment are complete tumor removal and maintenance of kidney function, both of which can be met by ablation. Given the limited treatment options, ablation may play a pivotal role in the management of patients with advanced CKD.

Prospective evaluation of core number of biopsy for renal tumor: are multiple cores preferable?

PURPOSE

This single-center, single-arm, prospective, open-label study was conducted to evaluate the optimal number of cores (single or multiple) in renal tumor biopsy.

MATERIALS AND METHODS

Forty-four biopsies of 44 tumors (mean diameter, 2.7 ± 1.0 cm; range, 1.6-5.0 cm) were included. Biopsy was performed under ultrasound or computed tomography fluoroscopy guidance using an 18-gauge cutting needle and the co-axial method. Two or more specimens were obtained, which were divided into first and subsequent specimens. "First specimen" and "all specimens" were histologically evaluated (i.e., appropriateness of specimen, histological diagnosis, subtype, and Fuhrman grade of renal cell carcinoma [RCC]) blindly and independently by two board-certified pathologists.

RESULTS

Multiple specimens were successfully and safely obtained in all the biopsies. All tumors were histologically diagnosed; 40 malignancies included 39 RCCs and 1 solitary fibrous tumor, and 4 benign lesions included 2 angiomyolipomas, 1 oncocytoma, and 1 capillary hemangioma. In all RCCs, the subtype could be determined (32 clear cell RCCs, 4 chromophobe RCCs, and 3 papillary RCCs), and the Furman grade was determined in 38 RCCs. When only the first specimen was evaluated, 22.7% of the specimens were inappropriate for diagnosis, and 34 (77.3%) were histologically diagnosed. The diagnostic yield was significantly lower than that of all specimens (P = 0.0044). Univariate analysis revealed that smaller lesions were a significant predictor of diagnostic failure (P = 0.020).

CONCLUSION

Biopsy with multiple cores significantly improved diagnostic yield. Thus, operators should obtain multiple cores during renal tumor biopsy.

Automatic renal carcinoma biopsy guidance using forward-viewing endoscopic optical coherence tomography and deep learning

Percutaneous renal biopsy (PRB) is commonly used for kidney cancer diagnosis. However, current PRB remains challenging in sampling accuracy. This study introduces a forward-viewing optical coherence tomography (OCT) probe for differentiating tumor and normal tissues, aiming at precise PRB guidance. Five human kidneys and renal carcinoma samples were used to evaluate the performance of our probe. Based on their distinct OCT imaging features, tumor and normal renal tissues can be accurately distinguished. We examined the attenuation coefficient for tissue classification and achieved 98.19% tumor recognition accuracy, but underperformed for distinguishing normal tissues. We further developed convolutional neural networks (CNN) and evaluated two CNN architectures: ResNet50 and InceptionV3, yielding 99.51% and 99.48% accuracies for tumor recognition, and over 98.90% for normal tissues recognition. In conclusion, combining OCT and CNN significantly enhanced the PRB guidance, offering a promising guidance technology for improved kidney cancer diagnosis.

Application of contrast-enhanced ultrasound in renal space-occupying lesion puncture biopsy

OBJECTIVE

The purpose of this study was to investigate the utility of contrast-enhanced ultrasound (CEUS) in percutaneous renal space-occupying lesion puncture biopsy.

METHODS

Ultrasound (US)-guided percutaneous needle biopsies were performed on 55 patients with renal space-occupying lesions, and the results were analyzed retrospectively. The US group included 36 patients receiving conventional US, and the contrast-enhanced ultrasound (CEUS) group included 22 patients, including 19 patients receiving CEUS directly and 3 patients receiving additional enhanced ultrasound due to the first conventional ultrasound puncture failure. The relevant data were subjected to statistical analysis.

RESULTS

The results of this study showed that the successful rate of obtaining effective tissue (100% vs. 75%) and the puncture accuracy (100% vs. 88.89%) in CEUS group were significantly higher than those in US group (P < 0.05). CEUS-guided puncture biopsy of renal mass, especially in the case of urothelial carcinoma of the renal pelvis, outperforms conventional ultrasound, and the difference was statistically significant (P < 0.05).

CONCLUSION

Percutaneous renal space-occupying lesion puncture biopsies aided by CEUS yield more effective tissue and improved puncture accuracy.

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.

Intrahepatic renal cell carcinoma implantation along a percutaneous biopsy and cryoablation probe tract

A man in his 60s underwent percutaneous biopsy and cryoablation of a right upper pole clear cell renal cell carcinoma followed by repeat cryoablation 8 months later for possible residual disease. The patient was followed with imaging with documented stability for 19 months after repeat ablation. However, imaging at 32 months demonstrated intrahepatic nodular enhancing lesions along the initial percutaneous biopsy and ablation tract, consistent with metastatic implantation. The patient underwent repeat percutaneous biopsy and two rounds of microwave ablation for treatment of the intrahepatic implants, with no residual disease at 10 months postablation. While needle tract seeding is a known complication of percutaneous manipulation of various abdominopelvic malignancies, there have been no prior reports of intrahepatic metastatic implants related to percutaneous renal cell carcinoma ablation. Awareness of this potential complication is important for treatment planning, informed consent and surveillance. This report shares our experience of the management of intrahepatic metastatic implants.

Differentiating the clinical and computed tomography imaging features of mixed epithelial and stromal tumors of the kidney to establish a treatment plan

Objective

To differentiate the clinical features and computed tomography imaging features in the two types of mixed epithelial and stromal tumor of the kidney (MESTK) and to establish a treatment plan for the MESTK types.

Methods

Seventeen patients who underwent multidetector computed tomography (MDCT) before surgery and had a pathological diagnosis of MESTK were enrolled. Their clinical information (R.E.N.A.L. nephrometry score (R.E.N.A.L.‐NS), radical nephrectomy (RN), partial nephrectomy (PN), etc.) were collected. The radiological features included renal sinus fat invagination (SFI), maximal diameter (MD), capsule and septa of the tumor, etc., were also analyzed. They were divided into two types according to the MD_solid/MD_tumor ratio (solid type with >60%; cystic type with ≤60%). An independent‐sample t‐test and Fisher exact test were used to assess the differences between the two groups.

Results

MESTKs demonstrated a variable multi‐septate cystic and solid components with a delayed enhancement. There were nine patients for solid type and eight patients for cystic type. Compared with solid type, the lesions in cystic type have larger MD (81.00 ± 37.91 vs. 41.22 ± 24.19, p = 0.020), higher R.E.N.A.L.‐NS (10.03 ± 0.50 vs. 8.95 ± 1.26, p < 0.001), higher RN (75.00% vs. 22.22%, p = 0.015), larger SFI (87.5% vs. 33.3%, p = 0.05), more septa (100% vs. 0%, p < 0.001), and more capsule (100% vs. 11.1%, p < 0.001).

Conclusion

Cystic type MESTK has more hazardous features (such as larger MD, higher R.E.N.A.L.‐NS, more RN, greater SFI, multiple septa) compared with solid type, suggesting that RN is more suitable for cystic type and PN for solid type.

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.

Endoscopic ultrasound-guided trans-duodenal fine-needle biopsy of a small renal mass: case report and review of the literature

Background

The incidental detection of small renal masses (SRMs) is increasing and biopsy to obtain pathological diagnosis is increasingly proposed as a diagnostic tool to guide further management. Renal mass biopsies are traditionally performed via a percutaneous approach. However, this is not always feasible due to anatomical limitations. A rarely reported alternative biopsy approach for SRMs is endoscopic ultrasound (EUS)-guided fine-needle biopsy (FNB). Herein, we describe a case of EUS-guided trans-duodenal FNB for a SRM that was not amenable to standard percutaneous biopsy.

Case presentation

A 48-year-old man was incidentally found to have a right-sided SRM measuring 2.9 × 2.2 × 2.4 cm during evaluation for a hernia. It was anterior, interpolar, completely endophytic and near the renal hilum. The tumor was not amenable to traditional percutaneous biopsy due to its anterior location. However, the renal mass was in close proximity to the descending duodenum and so it was felt that an EUS-guided trans-duodenal FNB would be feasible. The procedure was successful without any complications. The specimen adequacy was satisfactory for evaluation and consistent with renal papillary carcinoma with WHO/ISUP grade 3 nuclear changes.

Conclusion

Our case report demonstrated that EUS-guided trans-duodenal FNB was a safe and feasible approach to obtaining biopsy tissue diagnosis of a SRM that was not amenable to percutaneous biopsy.

[Dignity of Small Renal Masses: Implications for Diagnostics and Therapy]

Dignity of Small Renal Masses: Implications for Diagnostics and Therapy Abstract. The ubiquitous availability of radiological imaging has increased the diagnosis of renal incidentalomas with a diameter ≤4 cm. If malignancy is suspected, these are often treated surgically without prior biopsy. However, several studies demonstrate a relevant proportion of benign tumors, equating to a degree of overtreatment. There are no Swiss data available. Renal tumors resected in our center between 2006 and 2014 (n = 404) were retrospectively examined for size on cross-sectional imaging and their respective histology, identifying 221 (54.7 %) small renal masses with a diameter ≤4 cm. Of these, 62 (28 %) were benign and three (1.4 %) were of unclear or low malignant potential. Among the remaining 156 malignancies, 116 (74.4 %) were classified as prognostically favorable, allowing for active surveillance, if the patient's clinical context allows.

Percutaneous microwave ablation of renal cell carcinoma: practice guidelines of the ultrasound committee of Chinese medical association, interventional oncology committee of Chinese research hospital association

Imaging-guided percutaneous microwave ablation (MWA) with high thermal efficiency comprises rapid, successful management of small renal cell carcinomas (RCCs) in selected patients. Ultrasound Committee of Chinese Medical Association, Interventional Oncology Committee of Chinese Research Hospital Association developed evidence-based guidelines for MWA of RCCs after systematically reviewing the 1969-2019 literature. Systematic reviews, meta-analyses, randomized controlled trials, cohort, and case-control studies reporting MWA of RCCs were included and levels of evidence assessed. Altogether, 146 articles were identified, of which 35 reported percutaneous MWA for T1a RCCs and 5 articles for T1b RCCs. Guidelines were established based on indications, techniques, safety, and effectiveness of MWA for RCCs, with the goal of standardizing imaging-guided percutaneous MWA treatment of RCCs. Key points Microwave ablation is recommended for managing small renal cell carcinoma in selected patients. Imaging protocols are tailored based on the procedural plan, guidance, and evaluation. Patient's selection evaluation, updated technique information, clinical efficacy, and complications are recommended to standardize management. A joint task force (multidisciplinary team) summarized the key elements of the standardized report.

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.

Robotic-assisted Partial Nephrectomy for "Very Small" (<2 cm) Renal Mass: Results of a Multicenter Contemporary Cohort

BACKGROUND

Patient with "very small" (<2 cm) renal mass can be offered active surveillance, thermal ablation, or partial nephrectomy. The management strategy will consider patient preferences and prioritize potential harms associated with each of these options. To date, outcomes of robot-assisted partial nephrectomy (RAPN) in patients with "very small" renal masses have not been reported.

OBJECTIVE

To assess the outcomes of RAPN among patients with "very small" renal masses.

DESIGN, SETTING, AND PARTICIPANTS

This was a retrospective analysis of a multi-institutional database including RAPN cases performed at eight high-volume US and European centers between 2009 and 2019. Patients were stratified into two groups according to clinical tumor size: <2 cm ("very small" renal mass, study group) and 2-4 cm (control group).

INTERVENTION

RAPN for renal masses.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Baseline characteristics and intraoperative, pathological, and postoperative data were compared between the study and the control group. A "trifecta" was used as surrogate of "surgical quality."

RESULTS AND LIMITATIONS

Overall, a total of 1019 patients were included in the analysis. Of these, 352 had a renal mass of <2 cm (34.5%) and 667 (65.5%) had a renal mass of 2-4 cm. At baseline, the study group presented a lower rate of chronic kidney disease ≥stage III (p < 0.001), a lower RENAL score (p = 0.001), and lower rates of hilar (p = 0.04) and endophytic (p = 0.02) masses. Warm ischemia time was shorter for the study group (median 14 vs 18 min, p < 0.001), which also showed a lower rate of overall postoperative complications (9.6% vs 14.7%, p < 0.001) and no major complications. In terms of oncological outcomes, three and ten patients developed a local recurrence in the study and the control group, respectively (p = 0.1). In the study group, higher estimated glomerular filtration rates were found at discharge (p = 0.001) and at the last follow-up (p = 0.007), which showed a "trifecta" achievement of 90.6%. The retrospective design may limit the generalizability of the findings.

CONCLUSIONS

Whenever an active treatment is indicated or warranted, RAPN represents a minimally invasive management option for "very small" renal masses, as it carries minimal risk of complications and has minimal impact on renal function. While both active surveillance and kidney ablation remain valid management options in these cases, RAPN can be offered and discussed with patients as it provides excellent outcomes with low morbidity.

PATIENT SUMMARY

In this report, we observed that robot-assisted partial nephrectomy represents a true minimally invasive active treatment for "very small" renal masses (<2 cm), as it carries minimal risk of complications and has minimal impact on renal function.

Image-guided core biopsy of 2-cm or smaller renal tumors

PURPOSE

The purpose of this study was to retrospectively evaluate diagnostic yield, risk factors for diagnostic failure, and safety of image-guided core biopsy of renal tumors≤2cm.

MATERIALS AND METHODS

Eighty-four biopsies of 84 renal tumors (mean size, 1.5±0.4[SD] cm; range, 0.6-2.0cm) from 84 patients (53 men, 31 women; mean age, 61.7±12.7 [SD] years; age range, 34-87 years) were included. All adverse events (AEs) were evaluated based on the CIRSE classification. The 84 procedures were classified as diagnostic or nondiagnostic. Multiple variables related to the patients, tumors, and procedures were assessed to identify variables associated with diagnostic failure.

RESULTS

All 84 biopsies (100%) were technically successful, defined as penetration of the target and acquisition of some specimens. Eighty (80/84; 95.2%) biopsy procedures were diagnostic and four (4/84; 4.8%) procedures were nondiagnostic. Among 80 diagnosed renal tumors, 71/80 (88.8%) tumors were malignant (49 clear cell renal cell carcinomas [RCCs], 14 papillary RCCs, 3 chromophobe RCCs, 3 metastatic renal cancers, 1 lymphoma, and 1 unclassified RCC) and 9/80 (11.2%) lesions were benign (5 angiomyolipomas, 3 oncocytomas, and 1 inflammatory lesion). No significant differences existed in any variables between the two groups. A total of 57 (57/84; 67.9%) procedures resulted in 56 Grade 1, 2 Grade 2, and 1 Grade 3 AEs.

CONCLUSION

Image-guided biopsy of renal tumors≤2cm is safe and has a high diagnostic yield.

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%).

Assessing Genomic Copy Number Alterations as Best Practice for Renal Cell Neoplasia: An Evidence-Based Review from the Cancer Genomics Consortium Workgroup

Renal cell neoplasia are heterogeneous with diverse histology, genetic alterations, and clinical behavior that are diagnosed mostly on morphologic features. The Renal Cell Neoplasia Workgroup of the Cancer Genomics Consortium systematically evaluated peer-reviewed literature on genomic studies of renal cell carcinoma (RCC), including clear cell RCC, papillary RCC, chromophobe RCC, and the translocation RCC involving TFE3, TFEB and MITF rearrangements, as well as benign oncocytoma, which together comprise about 95% of all renal cell neoplasia. The Workgroup curated recurrent copy number alterations (CNAs), copy-neutral loss-of-heterozygosity (cnLOH), rearrangements, and mutations, found in each subtype and assigned clinical relevance according to established criteria. In clear cell RCC, loss of 3p has a disease-initiating role and most likely also in progression with mutations detected in VHL and other genes mapped to this arm, and loss of 9p and/or 14q has well-substantiated prognostic utility. Gain of chromosomes 7 and 17 are hallmark CNAs of papillary RCC, but patterns of other CNAs as detected by chromosomal microarray analysis (CMA) afford sub-classification into Type 1 and 2 with prognostic value, and for further sub-stratification of Type 2. Inherent chromosome loss in chromophobe RCC as detected by CMA is useful for distinguishing the eosinophilic variant from benign oncocytoma which in contrast exhibits few CNAs or rearranged CCND1, but share mitochondrial DNA mutations. In morphologically atypical RCCs, rearrangement of TFE3 and TFEB should be considered in the differential diagnosis, portending an aggressive RCC subtype. Overall, this evidence-based review provides a validated role for assessment of CNAs in renal cell neoplasia in the clinical setting to assist in renal cell neoplasm diagnosis and sub-classification within subtypes that is integral to the management of patients, from small incidentally found renal masses to larger surgically resected specimens, and simultaneously identify the presence of key alterations portending outcome in malignant RCC subtypes.

Difference in specimen weights with semi-automatic cutting biopsy needles

PURPOSE

To assess specimen weight difference of six types of semi-automatic cutting biopsy needles.

MATERIALS AND METHODS

We compared 18- and 20-gauge needles, one aspiration-type (STARCUT^® aspiration-type, TSK Laboratory, Tochigi, Japan) and five non-aspiration-type (MISSION^®, BARD, AZ; SuperCore™, Argon Medical Devices, TX; Temno Evolution^®, Care Fusion, IL; FINE CORE^®, Toray Medical, Tokyo, Japan; Quick-Core^®, Cook, IN) needles. Four biopsies were performed with each needle with the longest throw length on an excised bovine liver. The biopsies were repeated with new needles, four times with four different livers. STARCUT^® was used both with and without aspiration.

RESULTS

Sixteen specimens were obtained with each needle. In needles of gauges, STARCUT^® with aspiration provided the heaviest specimen and significantly heavier specimens were obtained with STARCUT^® with aspiration (P < 0.05) than five non-aspiration-type needles. The specimen weight differed significantly (P < 0.001) among all 18- and 20-gauge needles. The specimen weights did not differ significantly between aspiration and non-aspiration biopsies with STARCUT^® (6.32 vs. 5.97 mg with 18-gauge needle, P = 0.342; 1.95 vs. 1.92 mg with 20-gauge needle, P = 0.886).

CONCLUSION

Although STARCUT^® with aspiration provided the heaviest specimen, specimen weights were not significantly different between aspiration and non-aspiration biopsies. We assessed the specimen weight difference of six types of semi-automatic cutting biopsy needles. Significantly heavier specimens were obtained with STARCUT^® with aspiration than the other needles. The specimen weight differed significantly among all 18- and 20-gauge needles but did not differ significantly between aspiration and non-aspiration biopsies with STARCUT^®.

Current management of small renal masses

One of the consequences of the growing use of diagnostic imaging techniques is the notable growth in the detection of small renal masses presumably corresponding to localized tumors that are potentially curable with surgical treatment. When faced with the finding of a small renal mass, radiologists must determine whether it is benign or malignant, and if it is malignant, what subtype it belong to, and whether it should be managed with surgical treatment, with ablative techniques, or with watchful waiting with active surveillance. Small renal masses are now a clinical entity that require management different from the approaches used for classical renal cell carcinomas. In this scenario, radiologists are key because they are involved in all aspects of the management of these tumors, including in their diagnosis, treatment, and follow-up.

Does renal mass biopsy influence multidisciplinary treatment recommendations?

Purpose: To examine how a multidisciplinary team approach incorporating renal mass biopsy (RMB) into decision making changes the management strategy.Methods: A multidisciplinary team comprised of a radiology proceduralist, a pathologist and urologists convened monthly for renal mass conference with a structured presentation of patient demographics, co-mborbidities, tumor pathology, laboratory and radiographic features. Biopsy protocol was standardized to an 18-gauge core needle biopsy using a sheathed apparatus under renal ultrasound guidance. Biopsy diagnostic rate, and concordance with nephrectomy specimens were summarized. Descriptive statistics were used to evaluate influence of RMB on management decisions.Results: A total of 83 patients with a ≤4 cm mass were discussed, and 66% of patients underwent RMB. Of those, 87% were diagnostic with 9% of core biopsies showing benign pathology. Active surveillance (AS) was recommended for 34% of patients with biopsy data as compared to 64% of those without biopsy. Ablation was recommended for 38% of the biopsy cohort compared to 7% without biopsy. Partial nephrectomy rates were similar for both cohorts, approximately 17% and 22%, respectively. Our complication rate was 1.5%, with only 1 Clavien-Dindo Grade 2 complication. Histology was concordant in 93% of patients that ultimately underwent partial nephrectomy after biopsy.Conclusions: Over half of our SRM patients underwent a RMB that provided a diagnosis in 85% of cases. RMB aided in shared decision making by providing insight into the biology of renal masses, which helps to guide multidisciplinary management and consideration of nephron sparing options.

Needle track seeding in renal mass biopsies

A review and analysis of the literature demonstrates that needle track seeding in renal mass biopsy has been reported 16 times. This complication occurs almost exclusively among patients with papillary renal cell carcinoma. The incidence is associated with multiple punctures of the mass, the use of core needles of ≥20 gauge, and lack of a coaxial sheath. Needle tract seeding may be associated with tumor upstaging and a worse prognosis. Fine-needle aspiration has a significantly lower rate of needle track seeding compared with large core needle biopsy (>20-gauge needle). A more formalized risk-based system for interpreting renal mass fine-needle aspiration may be useful as clinicians choose among an increasing number of therapeutic options.

Histologic Diagnosis of Renal Mass Biopsy

CONTEXT.—

Core biopsy has been increasingly used for clinical decision-making in the management of patients with renal masses. The sensitivity and specificity of histologic diagnoses of renal mass biopsies depend on many factors such as adequate sampling and tissue processing, diagnostic skill and experience, and appropriate use of ancillary techniques.

OBJECTIVE.—

To review the indications, emphasize the importance of obtaining adequate diagnostic material, and introduce a general diagnostic approach, in conjunction with immunohistochemistry, in diagnosis of renal mass biopsies.

DATA SOURCES.—

Literature review and personal experiences in daily practice and consultation diagnosis of renal masses in a large tertiary medical center.

CONCLUSIONS.—

For renal mass biopsies, it is critical to obtain adequate diagnostic material and establish a standard laboratory procedure in working with small biopsy specimens. The key for the diagnosis is to be familiar with different tumor entities with characteristic morphology and to understand the wide spectrum of tumor heterogeneity. By developing a systematic approach, one can categorize the tumor and create a sensible differential diagnosis based on the growth pattern and cellular morphology. Immunohistochemistry is particularly helpful for renal mass biopsy diagnosis in selected situations.

Renal solitary fibrous tumor/hemangiopericytoma: computed tomography findings and clinicopathologic features

PURPOSE

To retrospectively characterize the clinical, pathological, and computed tomography (CT) findings of renal solitary fibrous tumor/hemangiopericytoma (rSFT/HPC).

METHODS

Twelve patients with rSFT/HPCs were enrolled. The CT findings and clinicopathological features were retrospectively reviewed.

RESULTS

This study included six male and six female patients (median age: 47; age range: 20-82 years). Eight benign (grade I) and four malignant (grade III) rSFT/HPCs were identified. Of the 12 lesions, 10 were in the renal sinus near the renal pelvis, while two replaced the whole kidney. Five lesions were well-defined, five were partially ill-defined, and two were ill-defined. Mild (5/12) and intermediate (1/12) hydronephrosis was observed. On the unenhanced CT images, ten tumors showed slightly higher density when compared to the normal renal parenchyma, and two masses were isodense to hypodense. After intravenous contrast medium injection, three enhancement patterns were observed, including "prolonged enhancement" (PE) (6/12), "gradual enhancement" (4/12), and "early washout" (2/12). A central fibrous scar was found in five patients. Compared to the grade I lesions, the grade III rSFT/HPC lesions tended to be larger (maximal diameter > 10 cm) and more heterogeneous with a higher incidence of the PE pattern.

CONCLUSIONS

We have shown that rSFT/HPCs usually arise from the renal sinus, and present as lobulated, slightly hyperdense, gradually enhancing soft tissue masses. CT findings, including large size, heterogeneity, and the PE pattern, may assist in the pre-operative identification of malignant grade III rSFT/HPCs.

Image-Guided Renal Interventions

Image-guided renal biopsies have an increasing role in clinical practice. Renal mass and renal parenchymal biopsy indications, techniques, and other clinical considerations are reviewed in this article. Image-guided renal mass ablation shows significant promise and increasing clinical usefulness as more studies demonstrate its safety and efficacy. Renal mass ablation indications, techniques, and other considerations are also reviewed.

Treatment approaches to small renal masses in patients of advanced age (≥75 years)

The elderly population is increasing in Turkey and across the world. With the frequent use of imaging modalities, the detection rate of coincidental small renal mass has also increased. Since small renal masses are generally not malignant, most of them can be followed up by active surveillance. In the current study, we examined the treatment options that can be offered to elderly patients with small renal masses. The optimum treatment method for patients of advanced age presenting with renal masses should be determined based on the presence of comorbidities such as age, renal function, and tumor characteristics.

Ultrasound-guided percutaneous laser ablation is safe and effective in the treatment of small renal tumors in patients at increased bleeding risk

PURPOSE

The aim of this retrospective study was to assess the safety and effectiveness of laser ablation (LA) in patients with small renal cell carcinomas (RCC) and increased risk of bleeding.

MATERIAL AND METHODS

From 2013 to 2017, nine patients (six males, three females, aged 68.5 ± 12.2 years) at high risk of bleeding underwent ultrasonography-guided LA for an RCC. Patients were considered at increased risk of bleeding because of impairment of coagulation parameters, concomitant antiplatelet therapy, or at-risk location of the tumor (one, five, and three patients, respectively). RCC diameter ranged from 11 to 23 mm. According to tumor size, two or three laser fibers were introduced through 21-gauge needles and 1800 J per fiber were delivered in 6 min with a fixed power of 5 W. Major and minor complications, technical success, and primary and secondary technical effectiveness and tumor recurrence were recorded.

RESULTS

Just one Grade 1 complication was observed: a small asymptomatic hematoma that spontaneously resolved. Technical success was 100%, 1 month technical efficacy was 88.9% (8/9 patients). One patient with residual tumor was successfully retreated 1 month later, and secondary efficacy rate was 100%. No local tumor recurrence occurred during a median follow-up of 26 months (range 11-49 months).

CONCLUSIONS

LA is safe and effective in the treatment of small RCC and might represent a valid option in patients with increased risk of bleeding.

Image-guided biopsy of small (≤4 cm) renal masses: the effect of size and anatomical location on biopsy success rate and complications

OBJECTIVE

To study the influence of tumour diameter and anatomy on the success and complication rates of small renal mass (SRM, ≤4 cm) core biopsy.

METHODS

Retrospective analysis of SRMs that underwent ultrasound or CT-guided biopsy. Diagnostic and complication rates were compared according to tumour size (subcategorised as axial diameter ≤2 cm, >2 to- ≤3 cm, >3-≤4 cm) and anatomical disposition (exophytic/endophytic, centrality, polar location and anterior/posterior).

RESULTS

94 patients (54 male; age range 21.8-84.3 years) with 95 SRMs underwent biopsy. The first biopsy was diagnostic in 81/95 (85.3%). Seven patients underwent repeat biopsy (6/7 diagnostic), to give an overall diagnostic rate of 91.5%. The primary diagnostic rates in the ≤2, >2-≤3 , >3-≤4 cm groups were 21/25 (84%); 38/44 (86.4%) and 22/26 (84.6%) respectively and were similar (p = 1.00). Anterior and upper pole SRMs were more likely to fail initial biopsy (odds ratio 13.8, p < 0.01; and odds ratio 4.35, p = 0.04) respectively, but other anatomical factors were not relevant. Complications occurred in 14% (all conservatively managed perinephric haematomas; Clavien-Dindo Grade 1) and size or location were not relevant.

CONCLUSION

Image-guided biopsy of SRMs has a high diagnostic rate irrespective of tumour size. Anterior and upper pole location had lower diagnostic rates. Biopsy should be considered for all patients with SRMs, if the result will impact on management and we list specific scenarios where an SRM biopsy may be helpful. Advances in knowledge: SRM size does not affect the likelihood of a diagnostic biopsy.

An In-vivo Prospective Study of the Diagnostic Yield and Accuracy of Optical Biopsy Compared with Conventional Renal Mass Biopsy for the Diagnosis of Renal Cell Carcinoma: The Interim Analysis

BACKGROUND

Lack of accuracy in preoperative imaging leads to overtreatment of benign renal masses (RMs) or indolent renal cell carcinomas (RCCs). Optical coherence tomography (OCT) is real time and high resolution, enabling quantitative analysis through attenuation coefficient (μ_OCT, mm^-1).

OBJECTIVE

To determine the accuracy and diagnostic yield of OCT and renal mass biopsy (RMB) for the differentiation of benign RMs versus RCC and oncocytoma versus RCC.

DESIGN, SETTING, AND PARTICIPANTS

From October 2013 to June 2016, 95 patients with solid enhancing RMs on cross-sectional imaging were prospectively included. All patients underwent subsequent excision or ablation.

INTERVENTION

Percutaneous, image-guided, needle-based OCT followed by RMB in an outpatient setting under local anaesthesia.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Accuracy and diagnostic yield, μ_OCT correlated to resection pathology or second biopsy during ablation. Tables (2×2) for RMB, receiver operating characteristic curve for OCT. Mann-Whitney test to differentiate μ_OCT of RMs.

RESULTS AND LIMITATIONS

RMB diagnostic yield was 79% with sensitivity, specificity, positive predictive value, and negative predictive value (NPV) of 100%, 89%, 99%, and 100%, respectively. Diagnostic yield and added value of OCT to differentiate RCC from benign was 99% and 15%, respectively. Significant difference was observed in median μ_OCT between benign RMs (3.2mm^-1, interquartile range [IQR]: 2.65-4.35) and RCCs (4.3mm^-1, IQR: 3.70-5.00), p=0.0171, and oncocytomas (3.38mm^-1, IQR: 2.68-3.95) and RCCs (4.3mm^-1, IQR: 3.70-5.00), p=0.0031. OCT showed sensitivity, specificity, positive predictive value. and NPV of 91%, 56%, 91%, and 56%, respectively, to differentiate benign RMs from RCCs and 92%, 67%, 95%, and 55%, respectively, to differentiate oncocytoma from RCC. Limitations include two reference standards and heterogeneity benign RMs.

CONCLUSIONS

Compared with RMB, OCT has a higher diagnostic yield. OCT accurately distinguishes benign RMs from RCCs, and oncocytoma from RCCs, although specificity and NPV are lower.

PATIENT SUMMARY

Optical coherence tomography, a new optical scan, exhibits similar sensitivity and positive predictive value than renal mass biopsy, although lower specificity and negative predictive value. Optical coherence tomography has a higher diagnostic yield for diagnosing renal cell carcinoma.

Diagnostic accuracy of contrast-enhanced ultrasound for characterization of kidney lesions in patients with and without chronic kidney disease

BACKGROUND

Patients with chronic kidney disease are at increased risk of cystic kidney disease that requires imaging monitoring in many cases. However, these same patients often have contraindications to contrast-enhanced computed tomography and magnetic resonance imaging. This study evaluates the accuracy of contrast-enhanced ultrasound (CEUS), which is safe for patients with chronic kidney disease, for the characterization of kidney lesions in patients with and without chronic kidney disease.

METHODS

We performed CEUS on 44 patients, both with and without chronic kidney disease, with indeterminate or suspicious kidney lesions (both cystic and solid). Two masked radiologists categorized lesions using CEUS images according to contrast-enhanced ultrasound adapted criteria. CEUS designation was compared to histology or follow-up imaging in cases without available tissue in all patients and the subset with chronic kidney disease to determine sensitivity, specificity and overall accuracy.

RESULTS

Across all patients, CEUS had a sensitivity of 96% (95% CI: 84%, 99%) and specificity of 50% (95% CI: 32%, 68%) for detecting malignancy. Among patients with chronic kidney disease, CEUS sensitivity was 90% (95% CI: 56%, 98%), and specificity was 55% (95% CI: 36%, 73%).

CONCLUSIONS

CEUS has high sensitivity for identifying malignancy of kidney lesions. However, because specificity is low, modifications to the classification scheme for contrast-enhanced ultrasound could be considered as a way to improve contrast-enhanced ultrasound specificity and thus overall performance. Due to its sensitivity, among patients with chronic kidney disease or other contrast contraindications, CEUS has potential as an imaging test to rule out malignancy.

TRIAL REGISTRATION

This trial was registered in clinicaltrials.gov, NCT01751529 .

Diagnostic Needle Biopsies in Renal Masses: Patient and Physician Perspectives

BACKGROUND

The utility of renal mass biopsies (RMB) in the diagnosis of kidney tumors remains debatable.

OBJECTIVE

To assess patient and urologist preferences regarding the utilization of RMB.

DESIGN, SETTING, AND PARTICIPANTS

Seventy-three patients diagnosed with renal tumors and 59 board-certified urologists were asked to participate in an interview-based study.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Using the standard gamble method we determined the minimal accepted accuracy at which RMB would be favored as part of the diagnostic process. Clinical and demographic data with potential to affect participants' preferences were analyzed.

RESULTS AND LIMITATIONS

At the time of the study interview, 56 patients (77%) were referred for kidney surgery and 17 (23%) opted for surveillance. Overall, 59% of the patients accepted some level of inaccuracy (1-20%), whereas 27% refuted a biopsy. Anxiety associated with the possibility of missing cancer was the primary determinant (82%) for declining RMB among patients referred for surgery, while fear of complications was the primary reason (58%) among those undergoing surveillance. Having an academic degree was associated with a lower accuracy threshold (p=0.03). Of the 59 participating urologists, 39% were reluctant to recommend RMB, primarily because of its inexorable nondiagnostic rate.

CONCLUSIONS

Most patients and urologists would favor RMB to facilitate their definitive treatment decision. Diagnostic accuracy of 95% was acceptable by the majority of study participants. The utility of RMB as part of the diagnostic algorithm for renal tumors should be discussed with patients, emphasizing its potential benefits and limitations.

PATIENT SUMMARY

Although needle biopsy seems to be an effective tool to differentiate benign from malignant kidney lesions, it is not commonly used. Our study shows that most patients would opt for a biopsy before definitive treatment decision despite its imperfect accuracy. Hence, the option of undergoing renal biopsy should be discussed with all patients diagnosed with small renal tumors.

Identification of clear cell renal cell carcinoma and oncocytoma using a three-gene promoter methylation panel

BACKGROUND

Promoter methylation has emerged as a promising class of epigenetic biomarkers for diagnosis and prognosis of renal cell tumors (RCTs). Although differential gene promoter methylation patterns have been reported for the major subtypes (clear cell, papillary and chromophobe renal cell carcinoma, and oncocytoma), validation of diagnostic performance in independent series have been seldom performed. Herein, we aimed at assessing the diagnostic performance of genes previously shown to be hypermethylated in RCTs in different clinical settings.

METHODS

Promoter methylation levels of HOXA9 and OXR1 were assessed by quantitative methylation specific PCR. ROC curves were generated for OXR1, OXR1 combined with MST1R and HOXA9. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy were computed, maximizing specificity. Methylation levels were also correlated with clinical and pathological relevant parameters.

RESULTS

HOXA9 and OXR1 promoter methylation was disclosed in 73 and 87% of RCTs, respectively. A two-gene methylation panel comprising OXR1 and MST1R identified malignancy with 98% sensitivity and 100% specificity, and clear cell renal cell carcinoma with 90% sensitivity and 98% specificity. HOXA9 promoter methylation allowed for discrimination between oncocytoma and both papillary and chromophobe renal cell carcinoma but only with 77% sensitivity and 73% specificity. Significantly higher OXR1 promoter methylation levels (p = 0.005) were associated with high nuclear grade in ccRCC.

CONCLUSIONS

A panel including OXR1 and MST1R promoter methylation allows specific and sensitive identification of renal cell tumors, and, especially, of clear cell renal cell carcinoma. Moreover, higher OXR1 promoter methylation levels associate with clear cell renal cell carcinoma nuclear grade, a surrogate for tumor aggressiveness. Thus, gene promoter methylation analysis might a useful ancillary tool in diagnostic management of renal masses.

Renal mass biopsy and thermal ablation: should biopsy be performed before or during the ablation procedure?

PURPOSE

To determine if renal mass biopsy should be performed before or during the ablation procedure with emphasis on complications and rate of ablation for renal cell carcinomas (RCC), benign tumors, and small renal masses without a histologic diagnosis.

METHODS

This HIPAA-compliant, single-center retrospective study was performed under a waiver of informed consent from the institutional review board. Two hundred eighty-four consecutive patients with a small renal mass (≤4.0 cm) treated with percutaneous thermal ablation between January 2001 and January 2015 were included. Two cohorts were identified based upon the timing of renal mass biopsy: separate session two weeks prior to ablation and same session obtained immediately preceding ablation. Clinical and pathologic data were collected including risk factors for non-diagnostic biopsy. Two-sided t test, χ ² test or Fischer's exact tests were used to evaluate differences between cohorts. Univariate and multivariate logistic regression models were constructed.

RESULTS

A histologic diagnostic was achieved more frequently in the separate session cohort [210/213 (98.6%) vs. 60/71 (84.3%), p < 0.0001]. The rate of ablation of RCC was higher in the separate session group [201/213 (94.4%) vs. 46/61 (64.7%), p = 0.001]. The rate of ablation for benign tumors [14/71 (19.7%) vs. 6/213 (2.8%), p < 0.0001] and small renal masses without a histologic diagnosis [3/213 (1.4%) vs. 11/71 (15.5%), p < 0.0001] was higher in the same session cohort. There were no high-grade complications in either cohort.

CONCLUSION

Performing renal mass biopsy prior to the day of ablation is safe, increases the rate of histologic diagnosis, and reduces the rate of ablation for benign tumors and small renal masses without a histologic diagnosis.

Smears are important for adequate cytologic diagnosis of kidney lesions

INTRODUCTION

Traditionally at our institution, smears with or without liquid-based cytology (LBC) and core biopsies (CBs) have been obtained by radiologists performing image-guided fine-needle aspiration biopsies (FNABs) of deep organs. Since 2015, however, there has been a shift to providing cytology with samples for LBC only when obtaining CBs. The impression among our institution's cytologists is that LBC alone is less often adequate for diagnosis compared with smears and LBC together. We examined a series of kidney FNABs pre- and post-"LBC only" to evaluate this impression.

MATERIALS AND METHODS

With institutional review board approval, we compared all kidney FNABs from 2012 to those from 2015. We recorded the type(s) of cytology preparation(s), the number of cytology slides, the cytology diagnosis, the concurrent CB diagnosis, and whether there was a subsequent excision and the excision diagnosis. We examined cytology and CB slides as needed.

RESULTS

In 2012, 105 patients underwent 111 kidney biopsies, 109 with smears made. In 2015, 58 patients underwent 62 kidney biopsies, 7 with smears made. In 2012, there were 13 (12%) nondiagnostic (ND) cytology cases and 19 (17%) cases where the cytology and CB diagnoses were discrepant. By comparison, in 2015, there were 20 (32%) ND cytology cases and 21 (33%) discrepant cases.

CONCLUSIONS

There were more cytology slides per case and fewer ND diagnoses in 2012 compared with 2015 (12% versus 32%, respectively, P = 0.001). Concordance was also better in 2012 (83% versus 67%, P = 0.015). We believe that our metrics would improve if we returned to the procedures followed in 2012.