Accuracy of diagnosis by guided biopsy of renal mass lesions classified indeterminate by imaging studies

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.

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.

Contemporary Results and Clinical Utility of Renal Mass Biopsies in the Setting of Ablative Therapy: A single center experience

PURPOSE

Clinical guidelines have recently included renal mass biopsy (RMB) in management algorithms, especially in the setting of small renal masses ≤ 4 cm (SRM) and ablative therapy. We sought to evaluate the diagnostic rates of RMB, factors associated with a non-diagnostic biopsy, its clinical utility, and its safety profile in the setting of ablative therapy.

MATERIALS AND METHODS

A total of 174 RMB from 167 patients, performed in a tertiary academic center from 01/2015 to 01/2019, were included. Patient demographics, radiographic mass size, RMB diagnoses, subsequent clinical management, and complications were retrospectively reviewed. RMBs were classified as diagnostic or non-diagnostic based on set criteria.

RESULTS

The mean mass size was 3.0 cm (range: 0.5-15.3 cm) and 140 biopsies (80%) were SRM. Among all RMB, 159 (91%) were diagnostic and 15 (9%) were non-diagnostic. Non-diagnostic biopsies were associated with small mass size, the presence of a cystic component (p < 0.00001) and fewer number of cores submitted (p = 0.0046). All non-diagnostic biopsies occurred in SRMs, where the mean mass size was significantly smaller than diagnostic biopsies (1.3 versus 3.2 cm, p = 0.001). RMB with concurrent ablation yielded non-diagnostic results more frequently than isolated RMBs (15% vs 2%, respectively).

CONCLUSIONS

RMB is useful for definitive diagnosis and clinical management in the setting of ablative therapy. Small mass size, cystic lesions, and fewer number of passes obtained are associated with non-diagnostic biopsies. When a renal mass diagnosis is particularly critical, a separate biopsy procedure prior to ablative therapy is recommended.

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.

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.

Aorta-Lesion-Attenuation-Difference (ALAD) on contrast-enhanced CT: a potential imaging biomarker for differentiating malignant from benign oncocytic neoplasms

OBJECTIVE

To evaluate whether the Aorta-Lesion-Attenuation-Difference on contrast-enhanced CT can aid in the differentiation of malignant and benign oncocytic renal neoplasms.

MATERIALS AND METHODS

Two independent cohorts-an initial (biopsy) dataset and a validation (surgical) dataset-with oncocytomas and chromophobe renal cell carcinomas (chRCC) were included in this IRB-approved retrospective study. A region of interest was placed on the renal mass and abdominal aorta on the same CT image slice to calculate an Aorta-Lesion-Attenuation-Difference (ALAD). ROC curves were plotted for different enhancement phases, and diagnostic performance of ALAD for differentiating chRCC from oncocytomas was calculated.

RESULTS

Seventy-nine renal masses (56 oncocytomas, 23 chRCC) were analyzed in the initial (biopsy) dataset. Thirty-six renal masses (16 oncocytomas, 20 chRCC) were reviewed in the validation (surgical) cohort. ALAD showed a statistically significant difference between oncocytomas and chromophobes during the nephrographic phase (p < 0.001), early excretory phase (p < 0.001), and excretory phase (p = 0.029). The area under the ROC curve for the nephrographic phase was 1.00 (95% CI: 1.00-1.00) for the biopsy dataset and showed the narrowest confidence interval. At a threshold value of 25.5 HU, sensitivity was 100 (82.2%-100%) and specificity was 81.5 (61.9%-93.7%). When tested on the validation dataset on measurements made by an independent reader, the AUROC was 0.93 (95% CI: 0.84-1.00) with a sensitivity of 100 (80.0%-100%) and a specificity of 87.5 (60.4%-97.8%).

CONCLUSIONS

Nephrographic phase ALAD has potential to differentiate benign and malignant oncocytic renal neoplasms on contrast-enhanced CT if histologic evaluation on biopsy is indeterminate.

Acute Kidney Injury Associated with Renal Cell Carcinoma Complicated by Renal Vein and Inferior Vena Cava Involvement

Acute kidney injury (AKI) is caused by diverse pathologies, although it may occasionally result from concurrent renal efflux disturbances. We herein describe a case of AKI in a patient complicated by renal cell carcinoma (RCC) with renal vein and inferior vena cava (IVC) involvement. A neoplastic thrombus which disrupted the blood flow in the renal vein appeared to play a role in the rapid decline in the renal function. Such a scenario has rarely been mentioned in the previous literature describing the cases of RCC complicated by AKI. Concerns regarding the diagnostic and therapeutic strategies for RCC are also discussed.

Renal transplant ultrasound: The nephrologist's perspective

One of the principal roles of a nephrologist is to closely monitor renal transplant allograft function and promptly evaluate any dysfunction. Renal transplant sonography has a major role in this assessment process given its ability to easily define renal transplant anatomy and surrounding structures. Abnormalities can be extrarenal or involve vascular, parenchymal and urological components of the graft and these can acutely or chronically influence graft function and survival. Procedural guidance as is required during allograft biopsy, as well as routine surveillance and screening for post transplant complications such as malignancy are also important applications of ultrasound in the management of renal transplant recipients. This article outlines key ultrasound findings and applications in renal transplantation from the clinician's perspective.

Management of Indeterminate Cystic Kidney Lesions: Review of Contrast-enhanced Ultrasound as a Diagnostic Tool

Indeterminate cystic kidney lesions found incidentally are an increasingly prevalent diagnostic challenge. Standard workup includes Bosniak classification with contrast-enhanced computed tomography (CT) or magnetic resonance imaging (MRI). However, these tests are costly and not without risks. Contrast-enhanced ultrasound (CEUS) is a relatively new technique with lower risk of adverse events than iodine-containing contrast or gadolinium. In our review of the evidence for characterization of cystic kidney lesions with CEUS, CEUS displayed sensitivity (89%-100%) and negative predictive value (86%-100%) comparable to contrast-enhanced CT or MRI, with no decrease in specificity compared with CT and only a slight decrease compared with MRI.

Systematic Review and Meta-analysis of Diagnostic Accuracy of Percutaneous Renal Tumour Biopsy

CONTEXT

The role of percutaneous renal tumour biopsy (RTB) remains controversial due to uncertainties regarding its diagnostic accuracy and safety.

OBJECTIVE

We performed a systematic review and meta-analysis to determine the safety and accuracy of percutaneous RTB for the diagnosis of malignancy, histologic tumour subtype, and grade.

EVIDENCE ACQUISITION

Medline, Embase, and Cochrane Library were searched for studies providing data on diagnostic accuracy and complications of percutaneous core biopsy (CB) or fine-needle aspiration (FNA) of renal tumours. A meta-analysis was performed to obtain pooled estimates of sensitivity and specificity for diagnosis of malignancy. The Cohen kappa coefficient (κ) was estimated for the analysis of histotype/grade concordance between diagnosis on RTB and surgical specimen. Risk of bias assessment was performed (QUADAS-2).

EVIDENCE SYNTHESIS

A total of 57 studies recruiting 5228 patients were included. The overall median diagnostic rate of RTB was 92%. The sensitivity and specificity of diagnostic CBs and FNAs were 99.1% and 99.7%, and 93.2% and 89.8%, respectively. A good (κ = 0.683) and a fair (κ = 0.34) agreement were observed between histologic subtype and Fuhrman grade on RTB and surgical specimen, respectively. A very low rate of Clavien ≥ 2 complications was reported. Study limitations included selection and differential-verification bias.

CONCLUSIONS

RTB is safe and has a high diagnostic yield in experienced centres. Both CB and FNA have good accuracy for the diagnosis of malignancy and histologic subtype, with better performance for CB. The accuracy for Fuhrman grade is fair. Overall, the quality of the evidence was moderate. Prospective cohort studies recruiting consecutive patients and using homogeneous reference standards are required.

PATIENT SUMMARY

We systematically reviewed the literature to assess the safety and diagnostic performance of renal tumour biopsy (RTB). The results suggest that RTB has good accuracy in diagnosing renal cancer and its subtypes, and it appears to be safe. However, the quality of evidence was moderate, and better quality studies are required to provide a more definitive answer.

Diagnostic significance of biopsies in renal masses

Introduction

We investigated the reliability and mapping of percutaneous needle core biopsies in the kidney in histopathological diagnosis of renal masses particularly for those with suspicious radiologic appearance in an attempt to prevent unnecessary nephrectomies.

Material and methods

Overall, 96 cases were included in our study that underwent radical nephrectomy or partial nephrectomy due to renal mass between November 2007 – March 2010. Ex–vivo biopsies 1 cm apart were obtained from the peripheral region of the mass. Additionally, half of these peripheral biopsies were obtained from the central region of the mass. Diagnostic yield of the biopsy cores were correlated. Sensitivity and specificity of peripheral and central biopsies in differentiating benign and malignant tissues were calculated.

Results

Sensitivity and specificity in differentiating malignant lesions were 93% and 87%, and 90% and 93% for peripheral and central biopsies, respectively. Positive and negative predictive values were 97% and 68%, and 98% and 64% for peripheral biopsies and central biopsies, respectively. Hazard ratio for cigarette smoking and presence of necrosis on CT scans were 4.76 (CI 1, 6–14.3; p = 0.04) and 3.32 (CI 1,2–9.2; p = 0.017) and 3.71 (CI 1.3–10.7; p = 0.013) and 3,51 (CI 1.3–9.6; p = 0.012) for peripheral and central biopsies, respectively.

Conclusions

Kidney biopsies can be performed in suspicious renal masses of central and peripheral biopsies with similar efficacy.

Heterogeneity and renal mass biopsy: a review of its role and reliability

Increased abdominal imaging has led to an increase in the detection of the incidental small renal mass (SRM). With increasing recognition that the malignant potential of SRMs is heterogeneous, ranging from benign (15%-20%) to aggressive (20%), enthusiasm for more conservative management strategies in the elderly and infirmed, such as active surveillance (AS), have grown considerably. As the management of the SRM evolves to incorporate ablative techniques and AS for low risk disease, the role of renal mass biopsy (RMB) to help guide individualized therapy is evolving. Historically, the role of RMB was limited to the evaluation of suspected metastatic disease, renal abscess, or lymphoma. However, in the contemporary era, the role of biopsy has grown, most notably to identify patients who harbor benign lesions and for whom treatment, particularly the elderly or frail, may be avoided. When performing a RMB to guide initial clinical decision making for small, localized tumors, the most relevant questions are often relegated to proof of malignancy and documentation (if possible) of grade. However, significant intratumoral heterogeneity has been identified in clear cell renal cell carcinoma (ccRCC) that may lead to an underestimation of the genetic complexity of a tumor when single-biopsy procedures are used. Heterogeneous genomic landscapes and branched parallel evolution of ccRCCs with spatially separated subclones creates an illusion of clonal dominance when assessed by single biopsies and raises important questions regarding how tumors can be optimally sampled and whether future evolutionary tumor branches might be predictable and ultimately targetable. This work raises profound questions concerning the genetic landscape of cancer and how tumor heterogeneity may affect, and possibly confound, targeted diagnostic and therapeutic interventions. In this review, we discuss the current role of RMB, the implications of tumor heterogeneity on diagnostic accuracy, and highlight promising future directions.

[Investigation and management of genito-urinary tuberculosis]

Genito-urinary tuberculosis is the fourth most common manifestation of the disease, but it is often underestimated by clinicians because of few and non-specific symptoms and insidious disease course. The most common urinary findings are multiple ureteral stenosis. The most common genital involvement is an epididymal nodule for men and a chronic salpingitis for women. The definite diagnosis of genito-urinary tuberculosis is obtained on the basis of culture studies. Due to the paucibacillary nature of the disease, especially of genital location in woman, a probable or presumptive diagnosis is frequently considered with several parameters including radiological imaging (abdominal CT-scan, pelvic ultrasound, pelvic MRI). Endoscopic and surgical procedures are frequently required to obtain specimens for histopathologic and bacteriological studies. Medical treatment is the method of choice, with a combination of four drugs, namely isoniazid, rifampicin, ethambutol and pyrazinamide, followed by a two-drug regimen, for a total of six month duration. Surgery might be indicated in complicated genito-urinary tuberculosis (decreased renal function, infertility, urologic complaints).

[Interventional sonography of the liver and kidneys]

CLINICAL/METHODICAL ISSUE

Optimization of ultrasound guided interventional procedures of the liver and kidneys using new imaging methods.

STANDARD RADIOLOGICAL METHODS

Punctures, biopsies, drainage, intraoperative ultrasound, fusion, embolization in correlation with ultrasound and other imaging methods.

METHODICAL INNOVATIONS

Real-time-sonography, contrast-enhanced ultrasound (CEUS) and fusion for planning, monitoring and postinterventional control.

PERFORMANCE

The use of CEUS enables better detection, characterization and execution of interventional procedures. Fusion facilitates detection.

ACHIEVEMENTS

The CEUS procedure is superior for detection and characterization of smaller lesions in comparison to the B scan. Fusion enables the performance of difficult interventional procedures.

PRACTICAL RECOMMENDATIONS

The B scan is the standard imaging method but CEUS and fusion could be helpful for smaller lesions.

Successful percutaneous radiologic management of renal cell carcinoma tumor seeding caused by percutaneous biopsy performed before ablation

A case is reported of the successful image-based detection, diagnosis, and percutaneous ablation of tumor seeding in a 61-year-old man that was caused by percutaneous biopsy of a renal cell carcinoma performed before cryoablation and was not detected until 4 years after the biopsy procedure. Although tumor seeding is a rare complication after percutaneous biopsy or ablation, this case emphasizes the importance of imaging surveillance of the needle tract used during both biopsy and ablation procedures, provides guidance on measures that can be used to minimize the occurrence of tumor seeding, and demonstrates that entirely radiologic management can be successful.

Experience of ultrasonography-guided percutaneous core biopsy for renal masses

Purpose

We evaluated the safety and accuracy of ultrasonography-guided percutaneous core biopsy collection in patients with renal masses.

Materials and Methods

From June 2008 to August 2012, 30 percutaneous core biopsies of renal masses were performed. The biopsies obtained were small tumors (<4 cm) with ambiguous radiologic findings or that met classic renal biopsy indications. The biopsy results were compared with the final pathological results after definitive surgical treatment. Ultrasonography was performed on the day after biopsy collection to rule out any complications.

Results

The mean age of the patients was 57.7 years, and the mean tumor size was 3.39 cm. Twelve of the lesions were in the left kidney, and 18 were in the right kidney. All but one core biopsy contained sufficient material for histopathological analysis. The biopsy results showed 17 renal cell carcinomas (56.7%), 3 angiomyolipomas (10.0%), 2 oncocytomas (6.7%), 1 adenocarcinoma (3.3%), and 7 benign lesions (23.3%). A total of 18 cases underwent surgery, and the pathological results confirmed the initial biopsy diagnosis for 17 of 18 cases (94.4%). The one (5.9%) inaccurate biopsy result was found to be a urothelial carcinoma of the kidney. No needle tract seeding was found in the pathological specimens or on follow-up imaging. A small perinephric hematoma (1-2 cm) was seen in 5 cases (16.7%), but all patients remained hemodynamically stable.

Conclusions

Ultrasonography-guided renal biopsy is a safe, effective, and accurate method for evaluating small renal masses. This procedure may help in selecting treatment modalities for small renal masses.

A new method of kidney biopsy using low dose CT-guidance with coaxial trocar and bard biopsy gun

Background

To explore a new method of kidney biopsy with coaxial trocar and bard biopsy gun under low dose computed tomography (CT)-guidance and evaluate its accuracy, safety, and efficacy.

Methods

Sixty patients underwent renal biopsy under CT-guidance. They were randomly divided into two groups: group I, low dose CT-guided (120 kV and 25 or 50 mAs) and group II, standard dose CT-guided (120 kV and 250 mAs). For group I, the coaxial trocar was accurately placed adjacent to the renal capsule of the lower pole, the needle core was removed, and samples were obtained with a bard biopsy gun. For group II, the coaxial trocar was not used. Total number of passes, mean biopsy diameter, mean glomeruli per specimen, mean operation time, mean scanning time, and mean radiation dose were noted. Dose-length product (DLP) was used to calculate the radiation doses. After 24 hours of the biopsy, ultrasound was repeated to identify any subcapsular hematoma.

Results

Success rate of biopsy in group I was 100% while using low dose CT-guidance along with coaxial trocar renal. There was no statistic differences bewteen group I and II in the total number of passes, mean biopsy diameter, mean glomeruli per specimen and mean time of operation and CT scanning. The average DLP of group I was lower as compared to the value of group II (p <0.05).

Conclusions

Kidney biopsy using coaxial trocar and bard biopsy gun under low dose CT was an accurate, simple and safe method for diagnosis and treatment of kidney diseases. It can be used for repeat and multiple biopsies, particularly suitable for obese and renal atrophy patients in whom the kidneys are difficult to image.

Arterial spin-labeling MR imaging of renal masses: correlation with histopathologic findings

PURPOSE

To assess the value of arterial spin-labeling (ASL) perfusion magnetic resonance (MR) imaging in the characterization of solid renal masses by using histopathologic findings as the standard of reference.

MATERIALS AND METHODS

This prospective study was compliant with HIPAA and approved by the institutional review board. Informed consent was obtained from all patients before imaging. Forty-two consecutive patients suspected of having renal masses underwent ASL MR imaging before their routine 1.5-T clinical MR examination. Mean and peak tumor perfusion levels were obtained by one radiologist, who was blinded to the final histologic diagnosis, by using region of interest analysis. Perfusion values were correlated with histopathologic findings by using analysis of variance. A linear correlation model was used to evaluate the relationship between tumor size and perfusion in clear cell renal cell carcinoma (RCC). P < .05 was considered indicative of a statistically significant difference.

RESULTS

Histopathologic findings were available in 34 patients (28 men, six women; mean age ± standard deviation, 60.4 years ± 11.7). The mean perfusion of papillary RCC (27.0 mL/min/100 g ± 15.1) was lower than that of clear cell RCC (171.6 mL/min/100 g ± 61.2, P = .001), chromophobe RCC (152.9 mL/min/100 g ± 80.7, P = .04), unclassified RCC (208.0 mL/min/100 g ± 41.1, P = .001), and oncocytoma (373.9 mL/min/100 g ± 99.2, P < .001). The mean and peak perfusion levels of oncocytoma (373.9 mL/min/100 g ± 99.2 and 512.3 mL/min/100 g ± 146.0, respectively) were higher than those of papillary RCC (27.0 mL/min/100 g ± 15.1 and 78.2 mL/min/100 g ± 39.7, P < .001 for both), chromophobe RCC (152.9 mL/min/100 g ± 80.7 and 260.9 mL/min/100 g ± 61.9; P < .001 and P = .02, respectively), and unclassified RCC (208.0 mL/min/100 g ± 41.1 and 273.3 mL/min/100 g ± 83.4; P = .01 and P = .03, respectively). The mean tumor perfusion of oncocytoma was higher than that of clear cell RCC (P < .001).

CONCLUSION

ASL MR imaging enables distinction among different histopathologic diagnoses in renal masses on the basis of their perfusion level. Oncocytomas demonstrate higher perfusion levels than RCCs, and papillary RCCs exhibit lower perfusion levels than other RCC subtypes.

Role of immunohistochemistry in the evaluation of needle core biopsies in adult renal cortical tumors: an ex vivo study

Multiple therapeutic options for renal tumors that are now available have put pathologists under increasing pressure to render diagnosis on limited material. Results on biopsies by hematoxylin and eosin (H&E) have historically not been encouraging. Currently, multiple immunohistochemical markers with differential expression in these renal tumors are available. We studied the utility of such markers on needle biopsies that were obtained ex vivo. After nephrectomy, two 18-guage cores were obtained and processed routinely. Expressions of carbonic anhydrase (CA) IX, CD117, α-methylacyl-CoA racemase (AMACR), cytokeratin 7 (CK7), and CD10 were evaluated. Results, with or without immunostaining, were compared with the final nephrectomy diagnosis. We studied 145 tumors, including 119 renal cell carcinomas (83 clear cell, 18 papillary, 14 chromophobe, and 4 type unclassified), 11 oncocytomas, and 15 miscellaneous tumors. Adequate evaluable material was present in 123 (85%) cases. In such biopsies, 81% of cases were correctly classified by H&E alone, with correct diagnosis in 90% of cases in the most common tumor subtypes (clear cell, papillary and chromophobe renal cell carcinoma, and oncocytoma). By adding immunostains, the accuracy was 90% overall and 99% among the 4 most common subtypes. The following extent and patterns of immuneexpression were highly useful in the diagnoses: diffuse, membranous CAIX expression in clear cell renal cell carcinoma, diffuse positivity for AMACR in papillary renal cell carcinoma, distinct peripheral cytoplasmic accentuation for CD117 in chromophobe renal cell carcinoma, widespread and intense positivity for CK7 in chromophobe and papillary renal cell carcinoma, and diffuse membranous reactivity in clear cell and patchy/luminal in papillary renal cell carcinoma for CD10. In conclusion, utilizing immunostains improves classification of renal tumors on needle biopsy, which may be of particular help for pathologists with limited experience. Both extent and patterns must be considered for a definitive diagnosis.

Watchful waiting in the treatment of the small renal mass

Objectives:

To evaluate the role and feasibility of observation with regard to the small renal mass.

Methods:

We performed a literature search of MEDLINE, reviewing the world literature relevant to the natural history, role of percutaneous biopsy and surveillance of the small renal mass.

Results:

The average yearly growth rate of most small renal masses ranges from 0.1 to 0.70 cm/yr with obvious exceptions. Clinical predictors of growth such as radiographic size at presentation, age, gender and tumor characteristics are not reliable. Approximately 1% develops metastatic disease while under surveillance. Contemporary series of percutaneous biopsy of small renal masses report sensitivity for malignancy to be 90%-98%. However, false-negative results can occur. For the majority of patients, the gold standard remains surgical extirpation.

Conclusions:

Watchful waiting is an acceptable option for management of small renal masses in the surgically unfit and elderly population. More information regarding the natural history and metastatic potential of small renal masses is needed. Percutaneous needle biopsy can be successful in detecting malignancy in selected patients with small renal masses. The role of needle biopsy for the small renal mass continues to evolve

Misdiagnosis of clear cell renal cell carcinoma

Clear cell renal cell carcinoma (RCC) represents the most common histological subtype of malignant kidney tumors. Based on symptoms alone, clear cell RCC is indistinguishable from other histological classes of RCC unless the tumor is present in the context of an RCC syndrome. Histopathological examination is, therefore, important to accurately identify clear cell RCC. Clear cell RCCs have characteristic morphological criteria; these tumors can be easily identified upon typical presentation, but diagnosis can be challenging when tumor cell pattern is unusual or when availability of tissue samples is limited. In this Review, the clinical, radiological and pathological characteristics of clear cell RCCs are described, as well as the potential tumors that can be confused with clear cell RCC and need to be considered in the differential diagnoses. Finally, the importance of an accurate diagnosis is highlighted in the context of the increasing use of preoperative tissue sampling and the prevalence of clear cell tumors associated with hereditary syndromes, which could have different therapeutic and prognostic implications for patients and their families.

The role of biopsy in incidental renal tumours

PURPOSE

Historically, the biopsy of renal masses was not advocated, and to date there remains some controversy on the role of biopsy for renal masses in making treatment decisions. With the widespread use of imaging methods, the incidental diagnosis of renal masses has increased, necessitating renal biopsies to better plan the management of these tumours. Here I review previous reports to define the role of biopsy in incidental renal tumours.

METHODS

Data were obtained from English-language studies listed in PubMed on the use of renal biopsy for evaluating incidental solid small renal tumours.

RESULTS

The biopsy of small renal tumours is increasingly accepted due to: the increase in the incidence of small renal tumours; the finding that a significant number of these tumours are benign; the availability of new management options, such as ablative therapy and surveillance strategies; that imaging alone is unable to predict the biological behaviour of these tumours; and advances in the pathological evaluation of the biopsies. The biopsy procedure has an acceptable complication rate but is not free of limitations. The current recommendations for the use of renal biopsy in small renal tumours are: to help in differentiating benign from malignant renal tumours; before or during ablative therapies and during the follow-up after ablative therapies, for defining treatment success or failure; and to exclude nonrenal cell primary tumours (metastasis and lymphoma) or benign conditions (abscess), which may not require surgery.

CONCLUSIONS

The biopsy of small renal tumours is a safe and accurate procedure, and can help in the planning of definitive patient management.

The role of percutaneous renal biopsy in the management of small renal masses

The use of percutaneous renal mass biopsy (RMB) has increased in recent years, likely in parallel with the growing incidence of renal cell carcinoma and small renal masses in particular. Biopsy and imaging techniques are improving, and diagnostic sufficiency and accuracy of RMB now are much higher in large-volume, experienced centers. Overall morbidity is low. This has led to a significant expansion of the indications for biopsy beyond documenting renal involvement for patients with metastatic disease or other systemic illnesses. While there still are limitations to its use and clinical judgment is paramount, RMB is proving to be a valuable tool in the clinical diagnosis and management of small renal masses.

Renal mass sampling: an enlightened perspective

Renal mass sampling (RMS) can be carried out by core biopsy or fine needle aspiration with each presenting potential advantages and limitations. The literature about RMS is confounded by a lack of standardized techniques, ambiguous terminology, imprecise definitions of accuracy, substantial rates of non-informative biopsies, and recurrent diagnostic challenges with respect to eosinophilic neoplasms. Despite these concerns, RMS has an expanding role in the evaluation and treatment of renal masses, in order to stratify biological aggressiveness and guide management that can range from surgery to active surveillance. Non-informative biopsies can be managed with surgical excision or repeat biopsy, with the latter showing encouraging results in recent studies. We propose a new classification in which all biopsies are categorized as non-informative versus informative, with the latter being subclassified as confirmed accurate, presumed accurate or confirmed inaccurate. This terminology will facilitate the comparison of results from various studies and stimulate progress. Incorporation of novel biomarkers and molecular fingerprinting into RMS protocols will likely allow for more rational management of patients with renal masses in the near future.

[Renal mass biopsy: results and safety in 2009]

The role of renal mass biopsies has been limited by suboptimal results in terms of diagnostic reliability, and their scant repercussion upon therapeutic decision taking. Recently, however, renal mass biopsies have generated renewed interest among urologists, as a result of the increased incidence of renal tumors, the introduction of new management options, and advances in histological diagnosis. A review has been made, based on a PubMed search of the most relevant publications on renal tumor biopsies in recent years. The most recent clinical studies reveal a high degree of diagnostic reliability in differentiating malignancy, histological type and grade in percutaneous biopsies of renal tumors, with a low rate of associated complications. However, routine use of the technique remains controversial, and its indications limited, due to the scant capacity of the renal biopsy findings to modify treatment decision.

Biopsy of renal masses: when and why

Percutaneous image-guided biopsy of renal masses is a safe and accurate procedure. Although once reserved for the diagnosis of unresectable renal cell carcinoma, metastases, lymphoma, and infection, today percutaneous image-guided biopsy has an expanded role. There is increasing awareness that a substantial proportion of small, solid renal masses are benign neoplasms. Although imaging can be used to diagnose most of them, some are incorrectly believed to represent renal cell carcinoma and unnecessary surgery may be performed. Based largely on advances in cytological techniques, percutaneous biopsy can be now be used to diagnose benign neoplasms and thus prevent them from being treated unnecessarily. Concurrent advances in percutaneous ablation have also promoted its use. As a result, there are 8 established indications for percutaneous biopsy, and reason to believe that the number of indications will expand further in the future.

Diagnostic yield of renal biopsies: a retrospective single center review

BACKGROUND

Previous studies have examined the spectrum of diseases identified with a kidney biopsy and the complications of the procedure. However, few studies have examined the utility of the test to clarify the diagnosis and guide treatment of pediatric patients. This retrospective, single-center chart review was performed to test the hypothesis that at least 80% of native kidney biopsies provide clinically valuable information that rationally guides diagnosis and patient management.

METHODS

200 biopsies performed between January 1, 2000 and June 30, 2008 were reviewed. A scheme composed of six categories was devised to classify the utility of each kidney biopsy.

RESULTS

196 complete case files were available for review. Twenty-four (12.2%) biopsies did not shed light on the diagnosis and were unhelpful in patient management - 21 biopsies (10.7%) were non-diagnostic and 3 (1.5%) failed to yield enough tissue for examination. The number of unhelpful biopsies did not cluster in any specific disease entity.

CONCLUSION

Our findings provide guidance to nephrologists about the total risk of a kidney biopsy, including uninformative results, when seeking informed consent for the procedure. The results suggest an appropriate balance has been reached which maximizes the use of kidney biopsies while minimizing the risk of this invasive procedure (word count: 202).

Renal tumor natural history: the rationale and role for active surveillance

Renal cell carcinoma (RCC) is the most common malignancy of the kidney. Despite widespread treatment at diagnosis, overall mortality rates associated with RCC have not decreased. Partly because of the more frequent use of abdominal imaging, diagnosis as an incidental finding has increased. The largest increase in incidence is in tumors smaller than 4 cm, termed small renal masses (SRMs). SRMs that are RCC may frequently be growth slowly and have a low risk of early progression. Initial active surveillance with delayed treatment for progression for selected patients should be considered. This should result in an overall decrease in treatment burden and cost saving.

Synchronous resections of intra-abdominal pathologies during radical nephrectomy. A case-linked cohort study evaluation of outcomes

OBJECTIVES

We report the outcomes of radical nephrectomy with synchronous surgical resection of intra-abdominal pathologies to guide practice.

PATIENTS AND METHODS

The data of patients requiring radical nephrectomy and surgical resection of a synchronous intra-abdominal pathology over a period of 12 years was extracted on pre-designed data extraction sheets from the case notes and included: age, sex, nature of second intra-abdominal pathology, intra-operative and postoperative details including complications, recurrence rate and survival on follow-up.

RESULTS

Two hundred and ninety patients underwent radical nephrectomy for non-metastatic renal cell carcinoma between January 1995 and January 2007. Amongst these, 30 patients (12%) had an additional surgical resection of a second intra-abdominal pathology at the time of radical nephrectomy. Fifteen underwent radical nephrectomy and surgical resection of a second intra-abdominal non-urological malignancy: colonic tumour - 8, rectal tumour - 3, oesophageal tumour - 2 and gastric tumour - 2. Fifteen patients underwent radical nephrectomy and surgical resection of a synchronous benign intra-abdominal pathology: gall bladder - 8, spleen - 3, uterine fibroid - 1, abdominal aortic aneurysm - 1, colonic polyp - 1 and suspected tumour infiltration of colon - 1. There was a higher morbidity (40%) of radical nephrectomy with synchronous resection of an additional intra-abdominal pathology as compared to radical nephrectomy alone group (25%); however it not was statistically significant (P-value 0.275).

CONCLUSION

It is feasible to offer simultaneous resection of synchronous intra-abdominal pathologies with renal cell carcinoma patients undergoing radical nephrectomy, albeit, at a higher morbidity.

Contemporary results of percutaneous biopsy of 100 small renal masses: a single center experience

PURPOSE

Percutaneous biopsy of small renal tumors has not been historically performed because of concern about complications and accuracy. We reviewed our experience with percutaneous needle biopsy of small renal masses to assess the safety and accuracy of the procedure, the potential predictors of a diagnostic result and the role of biopsy in clinical decision making.

MATERIALS AND METHODS

A total of 100 percutaneous needle biopsies of renal masses less than 4 cm were performed between January 2000 and May 2007 with 18 gauge needles and a coaxial technique under ultrasound and/or computerized tomography guidance. A retrospective chart review was performed to document the complication rate and the ability to obtain sufficient tissue for diagnosis. Tumor size, tumor type (solid vs cystic), image guidance, biopsy number and core length were assessed for the ability to predict a diagnostic biopsy.

RESULTS

No tumor seeding or significant bleeding was observed. Of the core biopsies 84 (84%) were diagnostic for a malignant (66) or a benign (18) tumor. Larger tumor size and a solid pattern were significant predictors of a diagnostic result. Histological subtyping and grading were possible on core biopsies in 93% and 68% of renal cell carcinomas, respectively. A total of 20 patients underwent surgery after a diagnostic biopsy. The histological concordance of biopsies and surgical specimens was 100%.

CONCLUSIONS

Percutaneous needle biopsy of renal masses less than 4 cm is safe and provides adequate tissue for diagnosis in most cases. Larger tumor size and a solid pattern are significant predictors of a successful biopsy. Renal tumor biopsy decreases the rate of unnecessary surgery for benign tumors and can assist the clinician with treatment decision making, especially in elderly and unfit patients.

The value of preoperative needle core biopsy for diagnosing benign lesions among small, incidentally detected renal masses

PURPOSE

We determined the safety and accuracy of preoperative needle core biopsy for diagnosing benign lesions among small incidental asymptomatic renal masses.

MATERIALS AND METHODS

Between February 2000 and December 2007 we received a total of 235 preoperative core biopsies from 222 less than 5 cm incidental renal masses. Biopsy results were correlated with surgical specimen final pathology findings or with patient followup if surgery was avoided.

RESULTS

Of the 235 biopsies 184 (78%) were diagnostic, whereas 51 (22%) were nondiagnostic due to insufficient material or contents of only normal, inflammatory, fibrotic or necrotic tissue, or blood clot. Diagnostic biopsies revealed 138 malignant (75%) and 46 benign (25%) lesions. Of these patients 108 (59%) underwent renal surgery, which showed a 100% biopsy accuracy rate for distinguishing malignant from benign lesions and a 98% rate for determining histological tumor type. Followup with radiological imaging was performed for 59 lesions in patients with nondiagnostic biopsies or benign masses and for 16 low grade malignant tumors in elderly patients. Lesions remained stable in 61 cases, showed minor size changes in 9 and resolved in 5. No patient has shown symptoms or required renal surgery to date. Significant biopsy related complications were noted in only 2 patients (0.9%).

CONCLUSIONS

We found that needle core biopsy was a safe and accurate technique for distinguishing between malignant and benign tumors in small asymptomatic incidentally detected renal masses. Biopsy of small tumors is associated with a relatively high rate of technical biopsy failure, although this may be addressed by adopting improved biopsy techniques, as discussed.

Border line cases and diagnostic doubts in definition kidney parenchymal and collecting tract neoplasia

Aim of this work is to present cases of renal neoplasms where all available diagnostic modalities and control exams were applied, still explorative surgery was needed. Asymptomatic tissue mass with diagnostic findings of hypovascular renal cell carcinoma and renal pelvic carcinoma were inconclusive. While percutaneous CT guided biopsy is advisable in such cases, it was not performed due to central, hilar localization of the lesions and its small dimensions. In rare cases, such ours are diagnosis is achieved by surgery-histology examination.

Interventional uroradiology

With advances in imaging capabilities and percutaneous instruments, many urologic diseases that were once managed surgically are now managed with minimally invasive image-guided techniques. Interventional uroradiology has evolved from simple renal biopsies for diagnostic confirmation, to percutaneous management of stones, to ablation of renal and adrenal tumors. Central to this evolution is the close cooperation with the urologist and nephrologist, each of whom provides specific skill sets and knowledge that can be used to successfully manage the patient. The purpose of this article is to detail the wide range of image-guided interventional techniques, including a discussion of indications, methods, success rates, and complications.

Pathologic concordance of sporadic synchronous bilateral renal masses

OBJECTIVES

To review the collective experience evaluating pathologic concordance rates of sporadic bilateral synchronous renal tumors reported in the Surveillance, Epidemiology, and End Results (SEER) database and the published English literature and treated at Fox Chase Cancer Center; specifically, to analyze concordance rates of malignant versus benign disease, histologic type, tumor stage, and nuclear grade.

METHODS

We reviewed the SEER database, the published English language literature, and our own institutional tumor registry to identify all cases of sporadic, synchronous localized (cT1-3N0M0) bilateral renal masses. Malignant and benign concordance rates were defined as agreement of any benign or malignant tumor type bilaterally. Histologic concordance was defined as bilateral histologic agreement. Tumors with mixed histologies were discordant unless all patterns were identical bilaterally. Nuclear grades were concordant if bilateral tumors were either "high" grade or "low" grade.

RESULTS

The malignant concordance rate in the SEER data was 99% (273 of 274), and benign concordance was 0 (0 of 1). In the published literature and Fox Chase Cancer Center series, malignant concordance rates ranged from 84% to 95%, whereas benign concordance ranged from 39% to 67%. The SEER data revealed a histologic concordance rate of 93% (256 of 274), and nuclear grade concordance was 85% (88 of 103).

CONCLUSIONS

These data demonstrate that in cases of bilateral sporadic localized synchronous renal masses, a diagnosis of ipsilateral renal cell carcinoma is associated with contralateral renal cell carcinoma in the vast majority of patients, whereas ipsilateral benign pathology is associated with contralateral benign disease at a substantially lower rate. Histologic concordance is similarly high, meaning most cases of clear cell or papillary tumors ipsilaterally are concordant in the contralateral kidney. Concordance rates of nuclear grade were slightly lower. These data are important when counseling and managing patients with bilateral synchronous sporadic renal tumors.