Renal Mass Core Biopsy: Accuracy and Impact on Clinical Management

Magnetic resonance imaging-guided renal biopsy shows high safety and diagnostic yield: a tertiary cancer center experience

OBJECTIVES

To evaluate the technical success and outcomes of renal biopsies performed under magnetic resonance imaging (MRI) using a closed-bore, 1.5-Tesla MRI unit.

MATERIALS AND METHODS

We retrospectively reviewed our institutional biopsy database and included 150 consecutive MRI-guided biopsies for renal masses between November 2007 and March 2020. We recorded age, sex, BMI, tumor characteristics, RENAL nephrometry score, MRI scan sequence, biopsy technique, complications, diagnostic yield, pathologic outcome, and follow-up imaging. Univariate logistic regression was used to assess the association between different parameters and the development of complications. McNemar's test was used to assess the association between paired diagnostic yield measurements for fine-needle aspiration and core samples.

RESULTS

A total of 150 biopsies for 150 lesions were performed in 150 patients. The median tumor size was 2.7 cm. The median BMI was 28.3. The lesions were solid, partially necrotic/cystic, and predominantly cystic in 137, eight, and five patients, respectively. Image guidance using fat saturation steady-state free precession sequence was recorded in 95% of the biopsy procedures. Samples were obtained using both fine-needle aspiration (FNA) and cores in 99 patients (66%), cores only in 40 (26%), and FNA only in three (2%). Tissue sampling was diagnostic in 144 (96%) lesions. No major complication developed following any of the biopsy procedures. The median follow-up imaging duration was 8 years and none of the patients developed biopsy-related long-term complication or tumor seeding.

CONCLUSIONS

MRI-guided renal biopsy is safe and effective, with high diagnostic yield and no major complications.

CLINICAL RELEVANCE STATEMENT

Image-guided renal biopsy is safe and effective, and should be included in the management algorithm of patients with renal masses. Core biopsy is recommended.

KEY POINTS

• MRI-guided biopsy is a safe and effective technique for sampling of renal lesions. • MRI-guided biopsy has high diagnostic yield with no major complications. • Percutaneous image-guided biopsy plays a key role in the management of patients with renal masses.

Renal cell carcinoma

The landscape of the management of renal cell carcinoma has evolved substantially in the last decade, leading to improved survival in localised and advanced disease. We review the epidemiology, pathology, and diagnosis of renal cell carcinoma and discuss the evidence for current management strategies from localised to metastatic disease. Developments in adjuvant therapies are discussed, including use of pembrolizumab-the first therapy to achieve overall survival benefit in the adjuvant setting. The treatment of advanced disease, including landmark trials that have established immune checkpoint inhibition as a standard of care, are also reviewed. We also discuss the current controversies that exist surrounding the management of metastatic renal cell carcinoma, including the use of risk assessment models for disease stratification and treatment selection for frontline therapy. Management of non-clear cell renal cell carcinoma subtypes is also reviewed. Future directions of research, including a discussion of ongoing clinical trials and the need for reliable biomarkers to guide treatment in kidney cancer, are also highlighted.

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

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

Primary Cardiac Intimal Sarcoma: Multi-Layered Strategy and Core Role of MDM2 Amplification/Co-Amplification and MDM2 Immunostaining

Primary cardiac tumours are relatively uncommon (75% are benign). Across the other 25%, representing malignant neoplasia, sarcomas account for 75-95%, and primary cardiac intimal sarcoma (PCIS) is one of the rarest findings. We aimed to present a comprehensive review and practical considerations from a multidisciplinary perspective with regard to the most recent published data in the specific domain of PCIS. We covered the issues of awareness amid daily practice clinical presentation to ultra-qualified management in order to achieve an adequate diagnosis and prompt intervention, also emphasizing the core role of MDM2 immunostaining and MDM2 genetic analysis. An additional base for practical points was provided by a novel on-point clinical vignette with MDM2-positive status. According to our methods (PubMed database search of full-length, English publications from January 2021 to March 2023), we identified three studies and 23 single case reports represented by 22 adults (male-to-female ratio of 1.2; male population with an average age of 53.75 years, range: 35-81; woman mean age of 55.5 years, range: 34-70) and a 4-year-old child. The tumour-related clinical picture was recognized in a matter of one day to ten months on first admission. These non-specific data (with a very low index of suspicion) included heart failure at least NYHA class II, mitral regurgitation and pulmonary hypertension, acute myocardial infarction, ischemic stroke, obstructive shock, and paroxysmal atrial fibrillation. Awareness might come from other complaints such as (most common) dyspnoea, palpitation, chest pressure, cough, asthenia, sudden fatigue, weakness, malaise, anorexia, weight loss, headache, hyperhidrosis, night sweats, and epigastric pain. Two individuals were initially misdiagnosed as having endocarditis. A history of prior treated non-cardiac malignancy was registered in 3/23 subjects. Distant metastasis as the first step of detection (n = 2/23; specifically, brain and intestinal) or during follow-up (n = 6/23; namely, intestinal, brain and bone, in two cases for each, and adrenal) required additional imagery tools (26% of the patients had distant metastasis). Transoesophageal echocardiography, computed tomography (CT), magnetic resonance imagery, and even 18F-FDG positronic emission tomography-CT (which shows hypermetabolic lesions in PCIS) represent the basis of multimodal tools of investigation. Tumour size varied from 3 cm to ≥9 cm (average largest diameter of 5.5 cm). The most frequent sites were the left atrium followed by the right ventricle and the right atrium. Post-operatory histological confirmation was provided in 20/23 cases and, upon tumour biopsy, in 3/23 of them. The post-surgery maximum free-disease interval was 8 years, the fatal outcome was at the earliest two weeks since initial admission. MDM2 analysis was provided in 7/23 subjects in terms of MDM2-positive status (two out of three subjects) at immunohistochemistry and MDM2 amplification (four out of five subjects) at genetic analysis. Additionally, another three studies addressed PCISs, and two of them offered specific MDM2/MDM2 assays (n = 35 patients with PCISs); among the provided data, we mention that one cohort (n = 20) identified a rate of 55% with regard to MDM2 amplification in intimal sarcomas, and this correlated with a myxoid pattern; another cohort (n = 15) showed that MDM2-positive had a better prognostic than MDM2-negative immunostaining. To summarize, MDM2 amplification and co-amplification, for example, with MDM4, CDK4, HMGA3, CCND3, PDGFRA, TERT, KIT, CCND3, and HDAC9, might improve the diagnosis of PCIS in addition to MDM2 immunostaining since 10-20% of these tumours are MDM2-negative. Further studies are necessary to highlight MDM2 applicability as a prognostic factor and as an element to be taken into account amid multi-layered management in an otherwise very aggressive malignancy.

The Utility of Renal Mass Biopsy in Large Renal Masses

Objectives

The role of needle core renal biopsy in large renal masses, defined as lesions larger than 4 cm, is debatable, as larger renal masses are associated with malignant histology. We aim to review the safety and impact of renal biopsy on the management of large renal masses.

Methods

A retrospective, single-center review of all renal biopsies performed between January 2011 and December 2020 at Royal Perth Hospital was conducted. Indications for biopsy, complications and final management plans were correlated to assess the value of biopsies in large renal masses.

Results

In total, 126 biopsies were performed. Indeterminate imaging findings and comorbidities were the main indications for biopsies. We identified 116 (92.1%) diagnostic biopsies and 10 (8.0%) non-diagnostic biopsies due to insufficient samples or inflammatory tissue. Of the diagnostic biopsies, 99 (78.6%) were malignant and 17 (13.5%) were benign. Unnecessary extirpative surgery was avoided in 17 patients. Histology included renal cell carcinoma (96%) and other malignancies such as urothelial carcinoma (3%) and non-Hodgkin's lymphoma (1%). Benign biopsies identified histology including angiomyolipoma (35.3%) and oncocytoma (52.5%). The median follow-up time was 68 months (range 19-132 months).

Conclusion

Renal biopsies in large renal masses may aid in preventing unnecessary surgery, especially in situations where imaging findings are equivocal or in patients with many comorbidities.

Renal tumor biopsy in patients with cT1b-T4-M0 disease susceptible to radical nephrectomy: analysis of safety, accuracy and clinical impact on definitive management

PURPOSE

Renal tumor biopsy was provided in patients candidate to radical nephrectomy for a renal mass ≥4 cm, to evaluate treatment deviation.

METHODS

Between 2008 and 2017, 102 patients with a solid renal mass ≥4 cm with no distant metastases underwent preliminary renal tumor biopsy. We investigated the proportion of patients who proceeded with radical nephrectomy, variables predicting non-renal cell carcinoma (RCC) and concordance between biopsy findings and definitive pathology.

RESULTS

Median tumor size was 70 mm (IQR 55-110). Clinical stage was cT1b in 41, cT2 in 33, cT3 in 25 and cT4 in three patients. A median of three (IQR 2-3) renal tumor biopsies were taken with 16/18 Gauge needles in 97% of cases. Clavien grade I complications occurred in five cases. Malignant tumors were documented in 84 patients: 78 RCCs and six non-RCCs. Fifteen biopsies documented oncocytoma and three were non-diagnostic. Grade was reported in 50 RCCs: 42 (84%) were low and eight (16%) high grade. Eighty-three patients proceeded with radical nephrectomy; six non-RCC malignant tumors underwent combined and/or intensified treatment; 13 of 15 patients with oncocytoma did not undergo radical nephrectomy (eight underwent observation). Definitive pathology confirmed diagnosis in all cases. Grade concordance was 84%, considering two tiers (high vs low grade). No preoperative clinical variable predicted definitive pathology.

CONCLUSIONS

Renal tumor biopsy is a safe procedure that leads to radical nephrectomy in most tumors ≥4 cm. Nonetheless, 20% of patients exhibited non-RCC histology. Renal tumor biopsy should be considered in this setting.

Overview of clinical management for older patients with renal cell carcinoma

The rapidly increasing pool of older patients being diagnosed with and surviving their cancer is creating many challenges. Regarding localized renal cell carcinoma, surgery is considered as gold standard treatment options even in older men, whereas active surveillance and ablation therapy are alternative options for a proportion of these patients. With regard to advanced disease, anti-vascular endothelial growth factor tyrosine kinase inhibitors (VEGFR-TKI) and immune check point inhibitor are standard treatment modalities, although treatment choice from multiple regimens and prevention of adverse events need to be considered. Better assessment techniques, such as comprehensive geriatric assessment to meet the unique needs of older patients, are a central focus in the delivery of high-quality geriatric oncology care. Through this process, shared decision-making should be adopted in clinical care to achieve optimal goals of care that reflect patient and caregiver hopes, needs and preferences. It is necessary to continue investigating oncological outcomes and complications associated with treatment in this population to ensure appropriate cancer care. In this narrative review, we completed a literature review of the various treatments for renal cell carcinoma in older patients that aimed to identify the current evidence related to the full range of the treatments including active surveillance, surgery, ablation therapy and systemic therapy. Prospectively designed studies and studies regarding geriatric assessment were preferentially added as references. Our goals were to summarize the real-world evidence and provide a decision framework that guides better cancer practices for older patients with renal cell carcinoma.

Image-guided percutaneous needle biopsy for the diagnosis of cancer of unknown primary

AIM

This study aimed to assess the efficacy of image-guided percutaneous needle biopsy in patients with suspected cancer of unknown primary.

METHODS

We conducted a retrospective observational study. Among 291 patients with suspected cancer of unknown primary who were referred to our institution between April 2011 and March 2014, 89 who underwent image-guided percutaneous needle biopsy and 27 who underwent surgical biopsy were defined as the image-guided percutaneous needle biopsy group and the surgical group, respectively. Patient backgrounds, diagnostic yields, promptness of biopsy, general anesthesia rates, and severe complication rates were compared between the two groups.

RESULTS

There was no significant difference in the patient backgrounds of the two groups. The diagnostic yields were 98.9% (95% confidence interval, 93.9%-99.8%) in the image-guided percutaneous needle biopsy group and 100% (95% confidence interval, 87.5%-100%) in the surgical biopsy group (no significant difference; p = 1.0). The mean time to biopsy was significantly shorter (6.5 days vs. 21.3 days; p < .0001) and general anesthesia was used in significantly fewer patients (0% vs. 40.7%; p < .0001) in the image-guided percutaneous needle biopsy group. There was no significant difference in the rate of serious complications between the two groups (p = 1.0).

CONCLUSION

As a biopsy procedure for patients with suspected cancer of unknown primary, image-guided percutaneous needle biopsy is equally diagnostic and safe for surgical biopsy and might be preferable to surgical biopsy in terms of promptness and not requiring general anesthesia.

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

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

The changing trends of image-guided biopsy of small renal masses before intervention-an analysis of European multinational prospective EuRECA registry

Objectives

To evaluate the use of pre-cryoablation biopsy for small renal masses (SRMs) and the effects of increasing uptake on histological results of treated SRMs.

Methods

From 2015 to 2019, patients with sporadic T1N0M0 SRMs undergoing percutaneous, laparoscopic, or open cryoablation from 14 European institutions within the European Registry for Renal Cryoablation (EuRECA) were included for the retrospective analysis. Univariate and multivariate logistic models were used to evaluate the trends, histological results, and the factors influencing use of pre-cryoablation biopsy.

Results

In total, 871 patients (median (IQR) age, 69 (14), 298 women) undergoing cryoablation were evaluated. The use of pre-cryoablation biopsy has significantly increased from 42% (65/156) in 2015 to 72% (88/122) in 2019 (p < 0.001). Patients treated for a benign histology are significantly more likely to have presented later in the trend, where pre-cryoablation biopsy is more prevalent (OR: 0.64, 95% CI 0.51–0.81, p < 0.001). Patients treated for undiagnosed histology are also significantly less likely to have presented in 2018 compared to 2016 (OR 0.31, 95% CI 0.10–0.97, p = 0.044). Patients aged 70+ are less likely to be biopsies pre-cryoablation (p < 0.05). R.E.N.A.L. nephrometry score of 10+ and a Charlson Comorbidity Index > 1 are factors associated with lower likelihood to not have received a pre-cryoablation biopsy (p < 0.05).

Conclusion

An increased use of pre-cryoablation biopsy was observed and cryoablation patients treated with a benign histology are more likely to have presented in periods where pre-cryoablation biopsy is not as prevalent. Comparative studies are needed to draw definitive conclusions on the effect of pre-cryoablation biopsy on SRM treatments.

Key Points

• The use of biopsy pre-ablation session has increased significantly from 42% of all patients in 2015 to 74% in 2019.

• Patients are less likely to be treated for a benign tumour if they presented later in the trend, where pre-cryoablation biopsy is more prevalent, compared to later in the trend (OR 0.64, 95% CI 0.51–0.81, p < 0.001).

• Patients with comorbidities or a complex tumour (R.E.N.A.L. nephrometry score > 10) are less likely to not undergo biopsy as a separate session to cryoablation.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00330-022-08556-2.

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.

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.

Ultrasound-guided percutaneous renal biopsy at a university hospital: retrospective analysis of success and complication rates

OBJECTIVE

To evaluate the success and complication rates of ultrasound-guided renal biopsy at a tertiary care hospital.

MATERIALS AND METHODS

This was a retrospective analysis of 97 ultrasound-guided renal biopsies, all performed by the same radiologist, between 1 March, 2017 and 31 October, 2019.

RESULTS

Of the 97 biopsies evaluated, 87 had a definitive pathological diagnosis. In five cases (5.4%), the biopsy results were inconclusive and a second procedure was required. In seven procedures (7.6%), there were complications, all of which were properly resolved.

CONCLUSION

Ultrasound-guided renal biopsy has proven to be a safe, effective method for the diagnosis of nephropathies, with high success rates.

Can preoperative renal mass biopsy change clinical practice and reduce surgical intervention for small renal masses?

INTRODUCTION

The role of renal biopsy prior to surgical intervention for a renal mass remains controversial despite the fact that for all other urological organs except the testicle, biopsy inevitably precedes treatment as is true for all other specialties dealing with solid masses (e.g. thyroid, breast, colon, liver, etc.). Accordingly, we sought to determine the impact of a routine biopsy regimen on the course of patients with cT1a lesions in comparison with a contemporary series of cT1a individuals who went directly to treatment without a preoperative biopsy.

METHODS

We analyzed a multi-institutional, prospectively maintained database of patients who underwent an office-based, ultrasound-guided, renal mass biopsy (RMB) for a cT1a renal mass (i.e. ≤4cm in largest dimension). Controls were selected from all patients in the database who had a cT1a renal lesion but did not undergo RMB. Both groups were analyzed for differences in treatment modality and surgical pathology results.

RESULTS

A total of 72 RMB and 73 control patients were analyzed. The groups were similar in regards to their baseline characteristics. Overall RMB diagnostic rate was 75%. Surgical pathology revealed that excision of benign tumors was eight-fold less in the RMB cohort compared to the control group (3% vs. 23%; P < 0.001). Additionally, the rate of active surveillance in the RMB cohort was nearly three times higher at 35% vs. 14% for the controls (P < 0.001). Biopsy was concordant with surgical pathology in 97% of cases for primary histology (i.e. benign vs. malignant), 97% for histologic subtype, and 46% for low (I or II) vs. high (III or IV) grade. On multivariate analysis patients who underwent surgical intervention without preoperative RMB were 6.7 times more likely to have benign histopathology compared to patients who underwent preoperative RMB (OR 6.7, 95% CI = 0.714 - 63.626, P = 0.096). There were no procedural or post-procedural RMB complications.

CONCLUSIONS

For patients with cT1a lesions, the implementation of routine office-based RMB led to a significant decrease in the rate of surgical intervention for benign tumors. This practice also resulted in a higher rate of active surveillance for the management of renal cortical neoplasms with benign histopathology compared to a control group.

Complications of renal interventions: a pictorial review of CT findings

A number of potential vascular and non-vascular complications can arise from surgical, extracorporeal shock wave lithotripsy, radiotherapy and radiological renal interventions, including percutaneous image-guided biopsy and drainage. Computed tomography scan is usually one of the first and most important diagnostic imaging examinations requested when a potential complication is suspected. There are a wide range of common and uncommon potential complications from renal interventions. An understanding of underlying risk factors is important to reduce potential complications from renal intervention. Radiologists play a crucial role in recognising and diagnosing post-renal intervention complications on computed tomography scans, which could significantly improve the patient’s prognosis.

A 25 year perspective on the evolution and advances in an understanding of the biology, evaluation and treatment of kidney cancer

The diagnosis, evaluation and management of patients with renal cell carcinoma has transformed in the 21st century. Utilizing biological discoveries and technological advances, the field has moved from blunt surgical and largely ineffective medical treatments, to nuanced and fine-tuned approaches based on biology, extent of disease and patient preferences. In this review we will summarize the last 25 years of progress in kidney cancer.

Learnable image histograms-based deep radiomics for renal cell carcinoma grading and staging

Fuhrman cancer grading and tumor-node-metastasis (TNM) cancer staging systems are typically used by clinicians in the treatment planning of renal cell carcinoma (RCC), a common cancer in men and women worldwide. Pathologists typically use percutaneous renal biopsy for RCC grading, while staging is performed by volumetric medical image analysis before renal surgery. Recent studies suggest that clinicians can effectively perform these classification tasks non-invasively by analyzing image texture features of RCC from computed tomography (CT) data. However, image feature identification for RCC grading and staging often relies on laborious manual processes, which is error prone and time-intensive. To address this challenge, this paper proposes a learnable image histogram in the deep neural network framework that can learn task-specific image histograms with variable bin centers and widths. The proposed approach enables learning statistical context features from raw medical data, which cannot be performed by a conventional convolutional neural network (CNN). The linear basis function of our learnable image histogram is piece-wise differentiable, enabling back-propagating errors to update the variable bin centers and widths during training. This novel approach can segregate the CT textures of an RCC in different intensity spectra, which enables efficient Fuhrman low (I/II) and high (III/IV) grading as well as RCC low (I/II) and high (III/IV) staging. The proposed method is validated on a clinical CT dataset of 159 patients from The Cancer Imaging Archive (TCIA) database, and it demonstrates 80% and 83% accuracy in RCC grading and staging, respectively.

To stage or not to stage: determining the true clinical significance of the biopsy tract through perinephric fat in assessing renal cell carcinoma

AIMS

Perinephric fat invasion (PFI) is a key component of renal cell carcinoma (RCC) staging, but there are limited data pertaining to biopsy tract seeding (BTS) resulting in perirenal tissue involvement [BTS with perinephric fat invasion (BTS-P)].The aim is to correlate clinical outcomes with pathologic stage to determine whether the presence of BTS-P should be considered a criterion to stage RCC as part of the pT3a category in the absence of any other upstaging variables.

MATERIALS AND RESULTS

We identified 304 renal biopsies from patients with subsequent nephrectomies for RCC; 33 of the tumours contained PFI. Each case was reviewed to determine the presence of BTS-P and other forms of invasion [e.g. non-BTS-P PFI, sinus fat invasion (SFI), and/or renal vein invasion (RVI)], and these findings were compared with survival outcomes. Ten (30%) of 33 tumours with PFI showed BTS-P as the only finding, and were otherwise pT1 tumours; six (60%) patients were alive without disease (AWOD) (mean, 77.5 months), three were lost to follow-up (LTF), and one died of other disease (DOOD). Two patients showed true PFI plus BTS-P; one was LTF and one is AWOD at 107 months. Ten (43%) of 23 patients with tumours with true invasion (PFI ± SFI and/or RVI) are AWOD (mean, 97.7 months), eight (35%) died of disease (DOD), four were LTF, and one DOOD. Kaplan-Meier survival curves showed that the cancer-specific survival was significantly worse in patients with true invasion (P = 0.044) than in those with BTS-P as the sole finding.

CONCLUSION

Patients with tumours showing BTS-P only appear to have better outcomes than those with other non-PFI invasion, suggesting that this finding should not be upstaged to pT3a. Additional studies are needed to corroborate the significance of our observations.

Imaging Characterization of Renal Masses

The detection of a renal mass is a relatively frequent occurrence in the daily practice of any Radiology Department. The diagnostic approaches depend on whether the lesion is cystic or solid. Cystic lesions can be managed using the Bosniak classification, while management of solid lesions depends on whether the lesion is well-defined or infiltrative. The approach to well-defined lesions focuses mainly on the differentiation between renal cancer and benign tumors such as angiomyolipoma (AML) and oncocytoma. Differential diagnosis of infiltrative lesions is wider, including primary and secondary malignancies and inflammatory disease, and knowledge of the patient history is essential. Radiologists may establish a possible differential diagnosis based on the imaging features of the renal masses and the clinical history. The aim of this review is to present the contribution of the different imaging techniques and image guided biopsies in the diagnostic management of cystic and solid renal lesions.

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.

Percutaneous Renal Ablation

Incidental small renal cell cancers are increasingly being diagnosed on cross-sectional imaging. This review article describes the indications for percutaneous ablation of small renal cell cancers, choice of ablation technologies and imaging follow-up.

Predictive Value of In Vivo MR Spectroscopy With Semilocalization by Adiabatic Selective Refocusing in Differentiating Clear Cell Renal Cell Carcinoma From Other Subtypes

OBJECTIVE. The purpose of this study is to evaluate the diagnostic value of in vivo MR spectroscopy (MRS) with semilocalization by adiabatic selective refocusing (semi-LASER MRS) in differentiating clear cell renal cell carcinoma (RCC) from the non-clear cell subtype. SUBJECTS AND METHODS. Sixteen patients with biopsy-proven RCC or masses highly suspicious for RCC were prospectively recruited to participate in the study. Single-voxel ¹H spectra were acquired using a 3-T MRI system, with a semi-LASER sequence acquired for renal tumors in 14 patients and for healthy renal tissue (control tissue) in 12 patients. Offline processing of the MR spectra was performed. MRI and spectra analysis were performed independently by radiologists who were blinded to the reference histopathologic findings. RESULTS. Semi-LASER MRS was diagnostic for nine of 11 patients (82%) with histopathologically proven clear cell RCC, showing a strong lipid peak in seven patients and a weaker lipid resonance in two others, whereas control spectra showed weakly positive findings in only one patient. MRS findings were negative for lipid resonance in two of three patients (67%) with non-clear cell tumors and were weakly positive in another patient. Semi-LASER MRS had a high sensitivity and positive predictive value of 82% and 90%, respectively, in addition to a specificity of 67%, a negative predictive value of 50%, and overall accuracy of 79% for the detection of clear cell RCC. Lipid resonance was detected by MRS for four of six clear cell RCCs with no intravoxel fat on chemical-shift MRI. CONCLUSION. The preliminary results of the present study show that semi-LASER MRS is promising for the noninvasive discrimination of clear cell RCC from non-clear cell RCC on the basis of detection of lipid resonance and that it provides an incremental yield compared with chemical-shift MRI.

Contrast-Enhanced Ultrasound in Renal Imaging and Intervention

PURPOSE OF REVIEW

In recent years, there has been renewed interest in the use of contrast-enhanced ultrasound (CEUS) in abdominal imaging and intervention. The goal of this article is to review the practical applications of CEUS in the kidney, including renal mass characterization, treatment monitoring during and after percutaneous ablation, and biopsy guidance.

RECENT FINDINGS

Current evidence suggests that CEUS allows accurate differentiation of solid and cystic renal masses and is an acceptable alternative to either computed tomography (CT) or magnetic resonance imaging (MRI) for characterization of indeterminate renal masses. CEUS is sensitive and specific for diagnosing residual or recurrent renal cell carcinoma (RCC) following percutaneous ablation. Furthermore, given its excellent spatial and temporal resolution, CEUS is well suited to demonstrate tumoral microvascularity associated with malignant renal masses and is an effective complement to conventional grayscale ultrasound (US) for percutaneous biopsy guidance. Currently underutilized, CEUS is an important problem-solving tool in renal imaging and intervention whose role will continue to expand in coming years.

Renal Mass Biopsy is Associated with Reduction in Surgery for Early-Stage Kidney Cancer

OBJECTIVE

To determine whether use of renal mass biopsy may be associated with a reduction in surgery for patients with small, localized renal cell carcinoma (cT1aN0M0), especially among older patients and patients with greater comorbidity burden.

METHODS

A total of 106,258 patients with cT1aN0M0 renal cell carcinoma from 2004 to 2015 were analyzed in the National Cancer Data Base. Multivariable logistic regression identified independent associations with nonsurgical management, receipt of biopsy, and pathologic upstaging. Marginal effects were derived by age and comorbidity. A sensitivity analysis was conducted in years identifying patients undergoing active surveillance (2010-2015).

RESULTS

There was increased use of biopsy (8.0%-15.3%) and nonsurgical management (11.7%-15.6%) over time. Biopsy was significantly associated with use of nonsurgical management (OR 4.80 [95%CI 4.58-5.02], P <.001) as well as active surveillance (OR 1.87 [1.69-2.07], P <.001) in the sensitivity analysis. Individual predicted probability of undergoing nonsurgical management ranged from 3% to 92% (median 31.4% with use of biopsy) and increased with age and comorbidity. Pathologic tumor upstaging (≥pT3a) occurred more frequently for patients receiving biopsy compared to no biopsy (5.8% vs 3.3%, P <.001). After adjustment, biopsy remained a statistically significant predictor of upstaging (OR 1.31 [95%CI 1.24-1.38], P <.001).

CONCLUSION

Overall, biopsy demonstrated a strong, independent association with reduced use of surgery for cT1aN0M0 kidney cancer, especially with increasing age and comorbidity. The potential association of renal mass biopsy with upstaging warrants caution, but it is uncertain whether it impacts prognosis relative to true perinephric fat invasion.

Percutaneous renal biopsy: approach, diagnostic accuracy and risks

PURPOSE OF REVIEW

This article provides a review of recent advances and issues regarding the controversial topic of renal mass biopsy (RMB). The purpose of this review is to provide an update on the current status of renal biopsy based on recently published literature. Here, we particularly focus on articles that have been published within the last 12 months.

RECENT FINDINGS

The main topics covered in this review are the approach, diagnostic accuracy and risks related to RMB.

SUMMARY

Current literature suggests that improvements in both technique and technological advancements of RMB have led to greater diagnostic accuracy and low risks to the patient. Newer technologies are leading toward innovative and harmless ways to diagnose kidney cancer, including liquid and image-based biopsy. However, it appears that the question of whether or not to instate renal biopsy as standard clinical practice has remained a highly debated controversy.

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.

Qualitative and quantitative CECT features for differentiating renal primitive neuroectodermal tumor from the renal cell carcinoma and its subtypes

OBJECTIVE:

To identify important qualitative and quantitative clinical and imaging features that could potentially differentiate renal primitiveneuroectodermal tumor (PNET) from various subtypes of renalcell carcinoma (RCC).

METHODS:

We retrospectively reviewed 164 patients, 143 with pathologically proven RCC and 21 with pathologically proven renal PNET. Univariate analysis of each parameter was performed. In order to differentiate renal PNET from RCC subtypes and overall RCC as a group, we generated ROC curves and determined cutoff values for mean attenuation of the lesion, mass to aorta attenuation ratio and mass to renal parenchyma attenuation ratio in the nephrographic phase.

RESULTS:

Univariate analysis revealed 11 significant parameters for differentiating renal PNET from clear cell RCC (age, p = <0.001; size, p =< 0.001; endophytic growth pattern, p < 0.001;margin of lesion, p =< 0.001; septa within the lesion, p =< 0.001; renal vein invasion, p =< 0.001; inferior vena cava involvement, p = 0.014; enhancement of lesion less than the renal parenchyma, p = 0.008; attenuation of the lesion, p = 0.002; mass to aorta attenuation ratio, p =< 0.001; and mass to renal parenchyma attenuation ratio, p =< 0.001). Univariate analysis also revealed seven significant parameters for differentiating renal PNET from papillary RCC. For differentiating renal PNET from overall RCCs as a group, when 77.3 Hounsfield unit was used as cutoff value in nephrographic phase, the sensitivity and specificity were 71.83 and 76.92 % respectively. For differentiating renal PNET from overall RCCs as a group, when 0.57 was used as cutoff for mass to aorta enhancement ratio in nephrographic phase, the sensitivity and specificity were 80.28 and 84.62 % respectively.

CONCLUSION:

Specific qualitative and quantitative features can potentially differentiate renal PNET from various subtypes of RCC.

ADVANCES IN KNOWLEDGE:

The study underscores the utility of combined demographic and CT findings to potentially differentiate renal PNET from the much commoner renal neoplasm, i.e. RCC. It has management implications as if RCC is suspected, surgeons proceed with resection without need for confirmatory biopsy. On the contrary, a suspected renal PNET should proceed with biopsy followed by chemoradiotherapy, thus obviating the unnecessary morbidity and mortality.

Diagnostic Accuracy of MRI for Detection of Papillary Renal Cell Carcinoma: A Systematic Review and Meta-Analysis

OBJECTIVE

The objective of our study was to perform a systematic review and meta-analysis of the diagnostic performance of MRI in differentiation of papillary renal cell carcinoma (RCC) from other renal masses.

MATERIALS AND METHODS

We performed searches of three electronic databases for studies that used MRI techniques to differentiate papillary RCC from other renal lesions. Methodologic quality was assessed, and diagnostic test accuracy was summarized using bivariate random-effects modeling or with construction of a summary ROC (SROC) curve.

RESULTS

Thirteen studies involving 275 papillary RCC lesions and 758 other renal masses met the inclusion criteria. Resulting summary estimates for the performance of MRI to differentiate papillary RCC from other renal lesions were a sensitivity of 79.6% (95% CI, 62.3-90.2%) and specificity of 88.1% (95% CI, 80.1-93.1%). In subgroup analysis, quantitative pooling of seven studies using enhancement in the corticomedullary phase resulted in a sensitivity of 85.6% (95% CI, 67.8-94.4%), specificity of 91.7% (95% CI, 76.0-97.5%), and area under the SROC curve of 0.894. Four studies used tumor appearance on T2-weighted imaging to detect papillary RCC, and results showed a pooled sensitivity of 89.9% (95% CI, 73.0-96.7%) and specificity of 84.9% (95% CI, 69.0-93.4%). Three studies used signal loss on T1-weighted in-phase imaging to detect papillary RCC but marked heterogeneity precluded pooling.

CONCLUSION

Meta-analysis supports moderate sensitivity and excellent specificity of quantitative enhancement in the corticomedullary phase for differentiating papillary RCC from other tumors. The accuracy of combining enhancement and T2 signal-intensity characteristics merits further evaluation as a potential aid for management decisions.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Diagnostic accuracy of image-guided biopsies in small (<4 cm) renal masses with implications for active surveillance: a systematic review of the evidence

OBJECTIVE:

To determine the safety and diagnostic accuracy of renal tumour biopsies in a defined population of small renal masses (SRMs) only <4 cm using 3 × 2 table, intention to diagnose approach. 3 × 2 table approach examines indeterminate results as a separate category rather than pushing these through traditional 2 × 2 table (four-cell matrix) approach.

METHODS:

A highly sensitive search was performed in the Cochrane Library, Database of Abstracts of Reviews of Effects; MEDLINE and MEDLINE in Process, EMBASE and conference proceedings (1966-2016) for the acquisition of data on the diagnostic accuracy and complications of RTB in patients with SRM <4 cm. Methodological quality and risk of bias was assessed using QUADAS-2. Test characteristics were calculated using conventional 2 × 2 contingency table analysis excluding non-diagnostic biopsies, and an intention-to-diagnose approach with a 3 × 2 table for pooled estimates of the sensitivity and specificity.

RESULTS:

A total of 20 studies were included with a total sample size of 974. The pooled estimates for sensitivity and specificity of RTB based upon univariate analysis using 2 × 2 table observed sensitivity 0.952 [confidence interval (CI) 0.908-0.979] and specificity 0.824 (CI 0.566-0.962). Using the 3 × 2 table and intention-to-diagnose principle, sensitivity 0.947 (CI 0.925-0.965) and specificity 0.609 (CI 0.385-0.803) decreased.

CONCLUSION:

RTB in SRMs (<4 cm) is associated with a high diagnostic sensitivity but poor specificity when non-diagnostic results are included by a 3 × 2 table for analysis (intention to diagnose approach). Risk of non-diagnostic results and poor quality of research need addressing through future studies, preferably by a well-designed prospective study appropriately powered for diagnostic accuracy using valid reference standards.

ADVANCES IN KNOWLEDGE:

A comprehensive synthesis of literature on image-guided biopsies in SRMs using a different methodology and study design.

Hemostatic Agents and Tissue Sealants: Potential Mimics of Abdominal Abnormalities

OBJECTIVE

Topical tissue sealants and hemostatic agents, seen on postoperative imaging in a variety of intraabdominal and pelvic locations, have the potential to be mistaken for abdominal abnormalities, especially if the radiologist is not aware of the patient's surgical history. The normal appearance of these agents may mimic abscesses, tumors, enlarged lymph nodes, or retained foreign bodies. Therefore, it is important to be familiar with their typical imaging appearances and to review the surgical records when needed to avoid misdiagnoses. The purpose of this article is to increase the radiologist's familiarity with various types of topical tissue sealants and hemostatic agents used during surgical and percutaneous procedures in the abdomen and pelvis along with their radiologic appearances.

CONCLUSION

Various types of hemostatic agents are now commonly used during surgery and percutaneous procedures in the abdomen and pelvis, and it is important to recognize the various appearances of these agents. Although there are suggestive features outlined in this article, the most important factor for the radiologist is to be aware of the patient's history and the possibility that a hemostatic agent may be present. On postoperative imaging, hemostatic agents may mimic abscesses, tumors, enlarged lymph nodes, or retained foreign bodies, and accurate diagnosis can save a patient unnecessary treatment. It is therefore crucial to incorporate knowledge of the patient's surgical history with recognition of the typical imaging appearances of hemostatic agents and other pseudolesions to avoid misdiagnoses.

Percutaneous image-guided core biopsy of solid renal masses: analysis of safety, efficacy, pathologic interpretation, and clinical significance

PURPOSE

To determine the efficacy, safety and clinical utility of CT and US-guided percutaneous renal mass biopsy.

MATERIALS AND METHODS

A retrospective IRB-approved, HIPAA-compliant study of a cohort of 183 consecutive patients who underwent percutaneous, CT or US-guided renal mass biopsy (RMB) from March 2002 through December 2012 was performed. RMB was performed in 183 consecutive patients for suspected solid renal mass of whom 14/183 (7.7%) were excluded because biopsies were performed at an outside institution, medical records were incomplete, or lesions were poorly visualized. Ten patients had multiple biopsies for new growing masses. Using US, CT or CT/US fusion-guidance, a 17G or 19G cannula needle was placed at the margin of the mass and an 18G or 20G core biopsy gun was used to obtain several tissue cores. Renal parenchymal biopsies for medical renal diseases were excluded. Imaging variables (including size, location, and extent of disease), number of core biopsies, patient demographics (age, gender), clinical indication, final pathologic diagnosis, immunohistochemical (IHC) studies, and subsequent final pathological diagnosis on nephrectomy were evaluated.

RESULTS

Of the 169 patients with 184 RMB, 121/169 (71.6%) were male with a mean age of 67.5 years. Of 184 RMB, 126 were malignant [126/184 (68.5%)], 37 [37/184 (20.1%)], were benign, and 21 (21/184 (11.4%) were nondiagnostic. IHC was performed in 131 biopsies (71.1%) and was diagnostic in 88.5% of those cases. Twenty-eight patients underwent subsequent partial nephrectomy; in 27/27 (100%) cases, RMB was concordant with nephrectomy for malignancy and in 21/27 (77.8%) RMB was concordant for subtype of RCC. Overall, the RMB sensitivity for detection of malignancy, specificity, and positive predictive value were 100%. The negative predictive value of benign RMB diagnosis was also 100%. There was a total of 14 (7.6%) complications, 13 minor (7.1%) and 1 major (0.5%). Of the minor complications, ten (5.5%) were postprocedural minor hematomas that resolved conservatively; one (0.5%) postprocedural vasovagal reaction; one (0.5%) episode of hematuria; and one (0.5%) episode of nausea and abdominal discomfort. No cases of renal pseudoaneurysm or tumor seeding attributed to biopsy were identified.

CONCLUSION

Percutaneous image-guided RMB is safe and highly diagnostic when combined with IHC and supports a greater role of RMB and imaging in evaluating renal masses when rendering appropriate treatments.

Quantitative computer-aided diagnostic algorithm for automated detection of peak lesion attenuation in differentiating clear cell from papillary and chromophobe renal cell carcinoma, oncocytoma, and fat-poor angiomyolipoma on multiphasic multidetector computed tomography

OBJECTIVE

To evaluate the performance of a novel, quantitative computer-aided diagnostic (CAD) algorithm on four-phase multidetector computed tomography (MDCT) to detect peak lesion attenuation to enable differentiation of clear cell renal cell carcinoma (ccRCC) from chromophobe RCC (chRCC), papillary RCC (pRCC), oncocytoma, and fat-poor angiomyolipoma (fp-AML).

MATERIALS AND METHODS

We queried our clinical databases to obtain a cohort of histologically proven renal masses with preoperative MDCT with four phases [unenhanced (U), corticomedullary (CM), nephrographic (NP), and excretory (E)]. A whole lesion 3D contour was obtained in all four phases. The CAD algorithm determined a region of interest (ROI) of peak lesion attenuation within the 3D lesion contour. For comparison, a manual ROI was separately placed in the most enhancing portion of the lesion by visual inspection for a reference standard, and in uninvolved renal cortex. Relative lesion attenuation for both CAD and manual methods was obtained by normalizing the CAD peak lesion attenuation ROI (and the reference standard manually placed ROI) to uninvolved renal cortex with the formula [(peak lesion attenuation ROI - cortex ROI)/cortex ROI] × 100%. ROC analysis and area under the curve (AUC) were used to assess diagnostic performance. Bland-Altman analysis was used to compare peak ROI between CAD and manual method.

RESULTS

The study cohort comprised 200 patients with 200 unique renal masses: 106 (53%) ccRCC, 32 (16%) oncocytomas, 18 (9%) chRCCs, 34 (17%) pRCCs, and 10 (5%) fp-AMLs. In the CM phase, CAD-derived ROI enabled characterization of ccRCC from chRCC, pRCC, oncocytoma, and fp-AML with AUCs of 0.850 (95% CI 0.732-0.968), 0.959 (95% CI 0.930-0.989), 0.792 (95% CI 0.716-0.869), and 0.825 (95% CI 0.703-0.948), respectively. On Bland-Altman analysis, there was excellent agreement of CAD and manual methods with mean differences between 14 and 26 HU in each phase.

CONCLUSION

A novel, quantitative CAD algorithm enabled robust peak HU lesion detection and discrimination of ccRCC from other renal lesions with similar performance compared to the manual method.

Renal Tumor Biopsy Technique

Objective:

To review hot issues and future direction of renal tumor biopsy (RTB) technique.

Data Sources:

The literature concerning or including RTB technique in English was collected from PubMed published from 1990 to 2015.

Study Selection:

We included all the relevant articles on RTB technique in English, with no limitation of study design.

Results:

Computed tomography and ultrasound were usually used for guiding RTB with respective advantages. Core biopsy is more preferred over fine needle aspiration because of superior accuracy. A minimum of two good-quality cores for a single renal tumor is generally accepted. The use of coaxial guide is recommended. For biopsy location, sampling different regions including central and peripheral biopsies are recommended.

Conclusion:

In spite of some limitations, RTB technique is relatively mature to help optimize the treatment of renal tumors.

Imaging of Extranodal Genitourinary Lymphoma

The genitourinary (GU) system is commonly affected by disseminated lymphoma. Rarely, lymphoma can originate from and remain localized to one of the GU organs and thus presents as primary extranodal disease. Up to 40% of lymphomas present as extranodal disease, with only 3% having the GU system as the primary site of involvement. This article describes and correlates the radiologic and pathologic features of extranodal lymphomatous disease affecting the GU system with specific focus on the kidneys, adrenal glands, testicles, and ovaries. Lymphoma of the uterine body and cervix, external female genitalia, urinary bladder, and prostate gland is briefly discussed.

Value of percutaneous needle biopsy of small renal tumors in patients referred for cryoablation

PURPOSE

To retrospectively evaluate the safety and diagnostic yield of needle biopsy of small renal tumors, and the clinical consequences of performing needle biopsy in patients referred for percutaneous cryoablation before their treatment.

MATERIAL AND METHODS

Biopsy was performed for 120 tumors (mean diameter, 2.2 cm) in 119 patients. All procedures were divided into diagnostic and non-diagnostic biopsies. Various variables were compared between the two groups. All cryoablation procedures were divided into two groups: procedures with or without simultaneous biopsy. The rates of benign or non-diagnostic tumors in each group were compared.

RESULTS

After performing 120 initial and eight repeat biopsies, Grade 1 bleedings occurred in 44 cases. Six tumors were non-diagnostic and 114 were pathologically diagnosed. There were no significant variables between the diagnostic and non-diagnostic biopsies. Unnecessary cryoablation was avoided in nine benign lesions by performing biopsy in advance. Cryoablation performed simultaneously with biopsy included significantly more benign or non-diagnostic tumors than cryoablation performed after biopsy (15.2% vs. 1.4%; p = .01).

CONCLUSIONS

Percutaneous biopsy of small renal tumors referred for cryoablation was a safe procedure with high diagnostic yield. The confirmation of pathological diagnosis prior to cryoablation is necessary because patients with benign tumors can avoid unnecessary treatment.

Differentiation of subtypes of renal cell carcinoma: dynamic contrast-enhanced magnetic resonance imaging versus diffusion-weighted magnetic resonance imaging

OBJECTIVE

The objective was to compare the performance of dynamic contrast-enhanced (DCE) and diffusion-weighted (DW) magnetic resonance (MR) imaging in the differentiation of subtypes of renal cell carcinoma (RCC).

MATERIALS/METHODS

This study included 45 renal tumors of clear cell (n=36) and non-clear-cell (n=9) RCC. The contrast enhancement ratios (CERs) and the apparent diffusion coefficient (ADC) values on MR imaging were compared between the clear cell and non-clear-cell RCC groups.

RESULTS

In the comparison of diagnostic performance between DCE and DW MR imaging, areas under the curves were 0.968 and 0.797 for the CERs of the corticomedullary and the ADC value.

CONCLUSION

The CER of the corticomedullary phase was more reliable in distinguishing between clear cell and non-clear-cell RCCs.

Nondestructive Diagnosis of Kidney Cancer on 18-gauge Core Needle Renal Biopsy Using Dual-color Fluorescence Structured Illumination Microscopy

OBJECTIVE

To present a novel imaging technique used for rapid, nondestructive histological assessment of renal neoplasias using a dual-component fluorescence stain and structured illumination microscopy (SIM).

MATERIALS AND METHODS

After Institutional Review Board approval, 65 total biopsies were obtained from 19 patients undergoing partial or radical nephrectomy. Biopsies were stained with a dual-component fluorescent, and optically sectioned SIM images were obtained from the surface of the intact biopsies. Specimens were subsequently fixed and analyzed using hematoxylin and eosin (H&E) histopathologic methods and compared with SIM images. A single, board-certified pathologist blinded to specimens reviewed all SIM images and H&E slides, and determined the presence or absence of neoplasias. Results of blinded diagnosis of SIM were validated against traditional pathology.

RESULTS

Of the 19 patients, 15 underwent robotic partial nephrectomies and 4 underwent laparoscopic nephrectomies. Indications included clinical suspicion of renal cell carcinoma. In total, 65 biopsy specimens were available for review. Twenty-one specimens were determined to be neoplastic on H&E, whereas 41 represented benign renal tissue. The final sensitivity and specificity of our study were 79.2% and 95.1%, respectively.

CONCLUSION

SIM is a promising technology for rapid, near-patient, ex vivo renal biopsy assessment. By improving the ability to rapidly assess sufficiency of biopsy specimens and enabling immediate diagnostic capability, SIM aids in more effective biopsy performance, tissue triage, and patient counseling regarding management options. Additionally, because tissue is preserved, effective utilization of downstream diagnostic tests and molecular assessments are possible.

Predictors of Delayed Intervention for Patients on Active Surveillance for Small Renal Masses: Does Renal Mass Biopsy Influence Our Decision?

OBJECTIVE

To review our clinical T1a renal mass active surveillance (AS) cohort to determine whether renal mass biopsy was associated with maintenance of AS.

MATERIALS AND METHODS

From our prospectively maintained database we identified patients starting AS from June 2009 to December 2011 who had at least 5 months of radiologic follow-up, unless limited by unexpected death or delayed intervention. The primary outcome was delayed intervention. Clinical, radiologic, and pathologic variables were compared. We constructed Kaplan-Meier survival curves for maintenance of AS. Cox multivariable regression analysis was performed to assess predictors of delayed intervention.

RESULTS

We identified 118 patients who met criteria for inclusion with a median radiologic follow-up of 29.5 months. The delayed intervention group had greater initial mass size and faster growth rate compared to those who continued AS. Rate of renal mass biopsy was similar between the 2 groups. In the multivariable analysis, size >2 cm (hazard ratio [HR] 3.65, 95% confidence interval [CI] 1.28-10.38, P = .015), growth rate (continuous by mm/year: HR 1.26, 95% CI 1.12-1.41, P < .001), but not renal biopsy (HR 1.52, 95% CI 0.70-3.30, P = .29), were associated with increased risk of delayed intervention. Time-to-event curves also showed that size was closely associated with delayed intervention whereas renal mass biopsy was not.

CONCLUSION

At our institution, growth rate and initial tumor size appear to be more influential than renal mass biopsy results in determining delayed intervention after a period of AS. Further analysis is required to determine the role of renal biopsy in the management of patients being considered for AS.