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The use of percutaneous renal tumour biopsy (RTB) as a diagnostic tool for the histological characterization of renal masses has increased dramatically within the last 30 years. This increased utilization has paralleled advances in imaging techniques and an evolving knowledge of the clinical value of nephron sparing surgery. Improved biopsy techniques using image guidance, coupled with the use of smaller gauge needles has led to a decrease in complication rates. Reports from series containing a large number of cases have shown the non-diagnostic rate of RTB to range from 4% to 21%. Re-biopsy has been shown to reduce this rate, while the use of molecular markers further improves diagnostic sensitivity. In parallel with refinements of the biopsy procedure, there has been a rapid expansion in our understanding of the complexity of renal cell neoplasia. The 2013 Vancouver Classification is the current classification for renal tumours, and contains five additional entities recognized as novel forms of renal malignancy. The diagnosis of tumour morphotype on RTB is usually achievable on routine histology; however, immunohistochemical studies may be of assistance in difficult cases. The morphology of the main tumour subtypes, based upon the Vancouver Classification, is described and differentiating features are discussed. [ABSTRACT FROM AUTHOR]

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. [Copyright &y& Elsevier]

Purpose: The incidence of renal cell carcinoma is increasing worldwide and there are new treatments for localized as well as metastatic tumors. The traditional role for percutaneous biopsy of renal masses has been limited, and so there is little general experience. There have been concerns about safety and accuracy. This review provides an update on the current techniques, indications and accuracy of needle biopsy of renal tumors. Materials and Methods: PubMed® and MEDLINE® were searched for English language reports of percutaneous needle core biopsy and fine needle aspiration of renal tumors that were published from 1977 to 2006. Results: With the development of new biopsy techniques and wider experience with percutaneous probe ablation therapies the risk of tumor seeding appears negligible. Significant bleeding is unusual and almost always self-limiting. At centers with expertise needle core biopsy with or without fine needle aspiration appears to provide adequate specimens for an accurate diagnosis in more than 90% of renal masses. Conclusions: Percutaneous biopsy of renal masses appears to be safe and it carries minimal risk of tumor spread. Urologists should consider increasing the indications for renal biopsy of small renal masses that appear to be renal cell carcinoma, especially in elderly and unfit patients. With more experience and followup preoperative biopsy has the potential to decrease unnecessary treatment since up to a third of small renal masses are now reported to be benign at surgery. Percutaneous biopsy may also allow a better selection of renal tumors for active surveillance and minimally invasive ablative therapies. Finally, there is potential for stratifying initial therapy for metastatic renal cell carcinoma by histological subtype and in the future molecular characteristics. [Copyright &y& Elsevier]

Objective: To determine whether a limited number of miRNAs could accurately classify the most common RCC subtypes, oncocytoma and unclassified RCC. In addition, we aimed to determine the diagnostic utility of our miRNA classifier by in situ hybridization (ISH). Methods: We extracted RNA from 93 formalin-fixed paraffin-embedded (FFPE) tissues including 30 ccRCC, 28 pRCC, 30 chRCC, 4 unclassified RCC tumours and 11 oncocytomas. We measured absolute expression of 6 miRNAs by qRT-PCR. Receiver operator characteristic curves were constructed and the areas under the curve were calculated to assess performance. We also tested miRNA expression ISH in an independent set of 98 FFPE renal tumours. Data and results:We developed a two-step miRNA classifier. In the first step, expressions of selected miRNAs were found to discriminate clear cell and papillary RCC from chromophobe RCC and oncocytoma. Two miRNAs were able to discriminate clear cell and papillary RCC from chromophobe RCC and oncocytoma (AUC: 0.91, p<0.0001). In the second step, the absolute expression of miR-126 was used to distinguish clear cell from papillary RCC (AUC: 0.98, p <0.0001) and two miRNAs were used to differentiate chromophobe from oncocytoma (AUC: 0.83, p =0.003). Select miRNAs were also useful in pointing to distinct histological types in unclassified RCC. ISH revealed that miRNAs display a nuclear staining pattern capable of distinguishing ccRCC, pRCC, chRCC and oncocytoma. Conclusions: miRNA expression can distinguish between RCC subtypes and oncocytoma. miRNA assessment by ISH is a clinically useful diagnostic tool that can complement current methods for renal tumour classification. [ABSTRACT FROM AUTHOR]

Introduction: Renal tumour biopsies (RTBs) can provide the histology of small renal masses (SRMs) prior to treatment decisionmaking. However, many urologists are reluctant to use RTB as a standard of care. This study characterizes the current use of RTB in the management of SRMs and identifies barriers to a more widespread adoption. Methods: A web-based survey was sent to members of the Canadian and Quebec Urological Associations who had registered email address (n=767) in June 2016. The survey examined physicians' practice patterns, RTB use, and potential barriers to RTB. Chi-squared tests were used to assess for differences between respondents. Results: The response rate was 29% (n=223), of which 188 respondents were eligible. A minority of respondents (12%) perform RTB in >75% of cases, while 53% never perform or perform RTB in <25% of cases. Respondents with urological oncology fellowship training were more likely to request a biopsy than their colleagues without such training. The most frequent management-related reason for not using routine RTB was a belief that biopsy won't alter management, while the most frequent pathology-related reason was the risk of obtaining a false-negative or a non-diagnostic biopsy. Conclusions: Adoption of RTBs remains low in Canada. Concerns about the accuracy of RTB and its ability to change clinical practice are the largest barriers to adoption. A knowledge translation strategy is needed to address these concerns. Future studies are also required in order to define where RTB is most valuable and how to best to implement it. [ABSTRACT FROM AUTHOR]

Abstract: Background: Renal cell carcinoma (RCC) encompasses different histologic subtypes. Distinguishing between the subtypes is usually made by morphologic assessment, which is not always accurate. Objective: Our aim was to identify microRNA (miRNA) signatures that can distinguish the different RCC subtypes accurately. Design, setting, and participants: A total of 94 different subtype cases were analysed. miRNA microarray analysis was performed on fresh frozen tissues of three common RCC subtypes (clear cell, chromophobe, and papillary) and on oncocytoma. Results were validated on the original as well as on an independent set of tumours, using quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analysis with miRNA-specific primers. Measurements: Microarray data were analysed by standard approaches. Relative expression for qRT-PCR was determined using the ΔΔCT method, and expression values were normalised to small nucleolar RNA, C/D box 44 (SNORD44, formerly RNU44). Experiments were done in triplicate, and an average was calculated. Fold change was expressed as a log2 value. The top-scoring pairs classifier identified operational decision rules for distinguishing between different RCC subtypes and was robust under cross-validation. Results and limitations: We developed a classification system that can distinguish the different RCC subtypes using unique miRNA signatures in a maximum of four steps. The system has a sensitivity of 97% in distinguishing normal from RCC, 100% for clear cell RCC (ccRCC) subtype, 97% for papillary RCC (pRCC) subtype, and 100% accuracy in distinguishing oncocytoma from chromophobe RCC (chRCC) subtype. This system was cross-validated and showed an accuracy of about 90%. The oncogenesis of ccRCC is more closely related to pRCC, whereas chRCC is comparable with oncocytoma. We also developed a binary classification system that can distinguish between two individual subtypes. Conclusions: MiRNA expression patterns can distinguish between RCC subtypes. [Copyright &y& Elsevier]