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Purpose: Current radio frequency ablation series do not distinguish renal cell carcinoma subtypes when reporting oncologic efficacy. Papillary neoplasms may be more amenable to radio frequency ablation than clear cell carcinoma because they are less vascular, which may limit heat energy loss. We report the long-term outcomes of patients treated with radio frequency ablation for small renal masses by renal cell carcinoma subtype., Materials and Methods: The records of patients undergoing radio frequency ablation for small renal masses (cT1a) at 2 institutions from March 2007 to July 2012 were retrospectively reviewed. Patients were included in analysis if they had biopsy confirmed clear cell or papillary renal cell carcinoma histology. Patients had at least 1 contrast enhanced cross-sectional image following radio frequency ablation. Demographic data between tumor subtypes were compared using the paired t-test. Oncologic outcomes were determined by Kaplan-Meier survival analysis and survivor curves were compared with the log rank test., Results: A total of 229 patients met study inclusion criteria. There were 181 clear cell tumors and 48 papillary tumors. Median followup was 33.2 months. There was no difference between tumor groups based on patient age, tumor size or grade, or months of followup. Five-year disease-free survival was 89.7% for clear cell tumors and 100% for papillary tumors (p = 0.041). There was no significant difference in overall survival (88.4% vs 89.6%, p = 0.764)., Conclusions: Radio frequency ablation outcomes seem to be determined in part by renal cell carcinoma subtype with clear cell renal tumors having less favorable outcomes. We hypothesize that this is due to differences in tumor vascularity. Our experience suggests that future tumor ablation studies should consider reporting outcomes based on tumor cell types., (Copyright © 2015 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.)

Background and Purpose: Long-term treatment of patients undergoing definitive management of a small renal mass depends largely on the final pathology determination. Preablation renal biopsy (PABx) is often the only source of determining pathology in patients undergoing thermal ablation of a small renal mass. We sought to evaluate patient and tumor characteristics that may play a role in determining the accuracy of a PABx obtained during radiofrequency ablation (RFA)., Methods: This retrospective study included a review of our prospectively collected database of all laparoscopic and CT-guided RFA (LRFA; CTRFA) performed in our center from November 2001 to July 2013. Three 18-gauge core biopsies were obtained per tumor. Pathology samples were stratified into diagnostic (group 1) and nondiagnostic (ND) (group 2). We used univariate and multivariate analysis to identify potential biopsy result-modifying factors including patient characteristics (age, body mass index [BMI]), biopsy approach (CTRFA vs LRFA), tumor size, orientation, depth, and polarity., Results: A total of 463 treatments in 411 patients were evaluated. Of these, 66% were CTRFA while 34% were LRFA. Mean patient age was 67.4 years (31-88), mean BMI was 28.3 kg/m(2) (16.6-47.2), and mean tumor size was 2.6 cm (0.3-5.5). There was a total of 73 (15.8%) ND biopsies. On multivariate analysis, CTRFA and medial tumors managed with either CTRFA or LRFA were found to be associated with an increased likelihood of a ND biopsy., Conclusion: PABx obtained in patients undergoing CTRFA and from medial tumors managed with either CTRFA or LRFA were more likely to be ND. Future RFA patients should be counseled appropriately. Additional biopsy cores may be needed in these subgroups. Further prospective studies are warranted to confirm these findings.

Background: The distinction between renal cell carcinoma conventional (clear cell) type with eosinophilic morphology (ccRCC), chromophobe renal cell carcinoma eosinophilic variant (chRCC), and renal oncocytoma (RO) is a common diagnostic dilemma. We aimed to identify an immunohistochemical panel to discriminate ccRCC from its morphologic mimics., Materials and Methods: Fifty-three renal neoplasms (19 ccRCC, 18 chRCC, and 16 RO) were selected. Immunohistochemical stains for CD10, cytokeratin 7 (CK7), c-Kit, E-cadherin, N-cadherin, kidney-specific cadherin (Ksp-cadherin), and Recepteur d'origine nantais (RON) were performed., Results: Ten (53%) of 19 ccRCC were positive for CD10, 11 (58%) for E-cadherin, 8 (42%) for N-cadherin, 5 (26%) for Ksp-cadherin, 9 (47%) for RON, 6 (32%) for CK7, and 5 (26%) for c-Kit. In chRCC/RO group, 5 of 34 (15%) were positive for CD10, 32 (94%) for E-cadherin, 2 (6%) for N-cadherin, 1 (3%) for Ksp-cadherin, 22 (65%) for RON, 14 (41%) for CK7, and 25 (25/32, 76%) for c-kit. Univariately, negative c-Kit [odds ratio (OR)=8.75, P=0.001, area under the receiver operating characteristic curve (AUC)=0.747], negative E-cadherin (OR=11.64, P=0.005, AUC=0.681), positive N-cadherin (OR=11.64, P=0.005, AUC=0.681), positive Ksp-cadherin (OR=11.79, P=0.031, AUC=0.617), and positive CD10 (OR=6.44, P=0.005, AUC=0.690) detects ccRCC versus chRCC/RO. Multivariate analysis showed significant association between CD10 positivity and ccRCC (OR=16.90, P=0.007) and between RON negativity and ccRCC (OR=7.17, P=0.047) when CK7 is negative., Conclusions: The best single predictors for ccRCC are negative c-Kit, negative E-cadherin, positive N-cadherin, positive Ksp-cadherin, and positive CD10. However, considering the studied markers, a combination of positive CD10 and negative CK7 and RON is considered the best immunohistochemical panel in distinguishing ccRCC from chRCC/RO.

Purpose: We investigate the use of 4-phase computerized tomography with intravenous contrast to help distinguish oncocytoma from renal cell carcinoma (RCC) in tumors <4 cm., Methods: We retrospectively identified patients who underwent surgical management for renal tumors <4 cm from 2005 to 2008. Patients who had pre-operative CT evaluation as per our institution's renal mass protocol and had confirmed pathological diagnosis of either oncocytoma or RCC were included in the study. Enhancement readings were obtained for the tumor and the renal cortex using the same slice simultaneously., Results: Our cohort involved 69 patients (46 men, 23 women; mean age 66) who presented with 79 renal masses. Histopathologically 40 were clear cell, 22 papillary, 5 chromophobe RCC and 12 oncocytoma. On the arterial, venous and delayed phase images, oncocytoma showed the highest mean enhancement change, i.e.,546, 396 and 239% followed by clear cell RCC 261, 261 and 174%, chromophobe RCC 147, 127 and 66% and papillary RCC 137, 184 and 118%, respectively. The enhancement pattern differed significantly on comparing oncocytoma with RCC (P < 0.007). The mean percentage contrast excreted at the end of the delayed phase was 33.3, 13.8, 32 and 53% for clear cell, papillary, chromophobe and oncocytoma, respectively., Conclusion: The enhancement and washout values in Hounsfield units obtained by multiphasic CT scan aid in distinguishing oncocytoma from the commonly seen subtypes of RCC in renal masses <4 cm. This preliminary study demonstrates that arterial phase enhancement greater than 500% and washout values of greater than 50% are exclusively seen in renal oncocytomas.

Renal cell carcinoma (RCC) with rhabdoid morphology (RCC-RM) is a recently described variant of RCC, which has an aggressive biologic behavior and poor prognosis, akin to sarcomatoid RCC. The current World Health Organization classification of RCC does not include the rhabdoid phenotype as a distinct histologic entity. The aim of this study is to investigate whether RCC-RM represents a dedifferentiation of a classifiable-type World Health Organization RCC or a carcinosarcoma with muscle differentiation. We reviewed 168 cases of RCC obtained between 2003 and 2008. From these cases, 10 (6%) were found to have areas of classic rhabdoid morphology. Immunohistochemistry for cytokeratin, epithelial membrane antigen, desmin, CD10, and CD117 was performed in each case using the labeled streptavidin-biotin method. Rhabdoid differentiation was identified in association with conventional-type RCC (9) and with unclassifiable-type RCC with spindle cell morphology (1). In all cases, both the rhabdoid and nonrhabdoid tumoral areas were positive for cytokeratin and epithelial membrane antigen and negative for desmin. Cytokeratin positivity in the rhabdoid areas was focal. In cases associated with conventional-type RCC, CD10 was positive in both the rhabdoid and nonrhabdoid foci. CD117 was negative in these tumors. The unclassifiable-type RCC with spindle cell morphology was negative for both CD10 and CD117. The similar immunophenotype between the rhabdoid and nonrhabdoid tumoral foci supports the origin of the rhabdoid cells from the classifiable-type RCC. Areas of rhabdoid morphology do not represent muscle metaplastic differentiation. Renal cell carcinoma with rhabdoid morphology may represent a dedifferentiation of a classifiable-type RCC, similar to that of sarcomatoid differentiation. The recognition of RCC-RM is important as it allows for the inclusion of these high-grade malignancies into a category associated with poor prognosis despite lacking the spindle cell component classically identified as sarcomatoid change., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Objective: To review trends in open partial nephrectomy (OPN) at our center, concentrating on patient selection, technique and perioperative complications., Methods: A comprehensive database was developed by chart review of consecutive patients undergoing OPN for renal masses at our center. Patient selection, technical modifications, perioperative morbidity, and histopathology were compared in patients undergoing OPN between 1992-1999, 2000-2003, and 2004-2008. Complications were divided into procedure-specific (PSCs) and nonspecific medical complications (NMCs). They were graded using the Common Terminology Criteria for Adverse Events (CTCAE), version 3.0., Results: One hundred and sixty-three OPNs were performed. Temporal trends identified include: an increase in the mean patient BMI (p = 0.04), an increase in the percentage of patients with central tumors (p < 0.001), decrease in cold ischemia time (p = 0.045), increasing use of a sequential renal vein clamp (p = 0.03), increasing utilization of tissue sealants (p < 0.001), reduced EBL (p = 0.05), reduced length of stay (p = 0.005), and a decline in PSCs from 16 to 7% (p = 0.002). The incidence of histologically benign tumors declined from 34 to 10% (p = 0.001). Thirty-three (20.2%) patients experienced perioperative complications: 70% were CTCAE grade 1 or 2 adverse events. BMI was the only factor that was found to be associated with the risk of complications on multivariate analysis [odds ratio 1.067, CI 95% (1.002-1.136); p = 0.031]., Conclusions: Increasingly, OPN is being utilized for a cohort of challenging patients who are overweight and have centrally located tumors. Despite this, the risk of PSCs is low. Patients who are overweight are at increased risk for perioperative NMCs.