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Management of residual or recurrent disease following thermal ablation of renal cortical tumors includes surveillance, repeat ablation, or surgical extirpation. We present a multicenter experience with regard to the management of this clinical scenario. Prospectively maintained databases were reviewed to identify 1265 patients who underwent cryoablation (CA) or radiofrequency ablation (RFA) for enhancing renal masses. Disease persistence or recurrence was classified into one of the three categories: (i) residual disease in ablation zone; (ii) recurrence in the ipsilateral renal unit; and (iii) metastatic/extra-renal disease. Seventy seven patients (6.1%) had radiographic evidence of disease persistence or recurrence at a median interval of 13.7 months (range, 1-65 months) post-ablation. Distribution of disease included 47 patients with residual disease in ablation zone, 29 with ipsilateral renal unit recurrences (all in ablation zone), and one with metastatic disease. Fourteen patients (18%) elected for surveillance, and the remaining underwent salvage ablation (n = 50), partial nephrectomy (n = 5), or radical nephrectomy (n = 8). Salvage ablation was successful in 38/50 (76%) patients, with 12 failures managed by observation (3), tertiary ablation (6), and radical nephrectomy (3). At a median follow-up of 28 months, the actuarial cancer-specific survival and overall survival in this select cohort of patients was 94.8 and 89.6%, respectively.

* Context.--Active surveillance of small renal masses highlights the need for accurate prognostication of biopsies. Objective.--To comprehensively evaluate the accuracy of biopsies in assessing known prognostic parameters including histologic subtype by comparison with subsequent nephrectomy samples. Design.--We retrospectively identified patients at University of Texas Southwestern Medical Center, Dallas, Texas, who had a biopsy for a renal mass between 2004-2018. Biopsy samples were evaluated for known prognostic factors such as tumor grade, necrosis, sarcomatoid/ rhabdoid change, and BRCA1-associated protein-1 (BAP1) status, which we previously showed is an independent prognostic factor for clear cell renal cell carcinoma. Accuracy was determined by comparison with subsequent analyses of nephrectomy specimens. Statistical analyses were performed to assess biopsy accuracy and correlation with tumor size and pathologic stage. Results.--From 805 biopsies with a diagnosis of renal neoplasm, 178 had subsequent resection of the biopsied tumor. Concordance rate for histologic subtype was 96.9% ([kappa] [w], 0.90; 95% CI, 0.82-0.99) and excellent for small renal masses (98.8%; k [w], 0.97; 95% CI, 0.90-1). Aongst the prognostic variables evaluated, BAP1 immunohistochemistry in clear cell renal cell carcinoma had the highest agreement (94.8%; k [w], 0.83; 95% CI, 0.66-0.99). The presence of 1 or more aggressive features (grade 3-4, tumor necrosis, BAP1 loss, sarcomatoid/rhabdoid change) in a biopsy significantly correlated with pT stage (P = .004). Conclusions.--Biopsy analyses showed high accuracy for subtyping renal tumors, but it underestimated several poor prognostic features. Addition of BAP1 for clear cell renal cell carcinoma may increase prognostic accuracy. If validated, routine incorporation of BAP1 immunohistochemistry in clear cell renal cell carcinoma biopsies may refine prognosis and aid in the selection of patients for active surveillance., The incidence of kidney cancer continues to increase. (1) Many of these tumors are small masses discovered incidentally owing to increasing use of cross-sectional imaging. (2-4) Renal cell carcinoma (RCC) [...]

Purpose To assess the diagnostic performance and interreader agreement of a standardized diagnostic algorithm in determining the histologic type of small (≤4 cm) renal masses (SRMs) with multiparametric magnetic resonance (MR) imaging. Materials and Methods This single-center retrospective HIPAA-compliant institutional review board-approved study included 103 patients with 109 SRMs resected between December 2011 and July 2015. The requirement for informed consent was waived. Presurgical renal MR images were reviewed by seven radiologists with diverse experience. Eleven MR imaging features were assessed, and a standardized diagnostic algorithm was used to determine the most likely histologic diagnosis, which was compared with histopathology results after surgery. Interreader variability was tested with the Cohen κ statistic. Regression models using MR imaging features were used to predict the histopathologic diagnosis with 5% significance level. Results Clear cell renal cell carcinoma (RCC) and papillary RCC were diagnosed, with sensitivities of 85% (47 of 55) and 80% (20 of 25), respectively, and specificities of 76% (41 of 54) and 94% (79 of 84), respectively. Interreader agreement was moderate to substantial (clear cell RCC, κ = 0.58; papillary RCC, κ = 0.73). Signal intensity (SI) of the lesion on T2-weighted MR images and degree of contrast enhancement (CE) during the corticomedullary phase were independent predictors of clear cell RCC (SI odds ratio [OR]: 3.19; 95% confidence interval [CI]: 1.4, 7.1; P = .003; CE OR, 4.45; 95% CI: 1.8, 10.8; P < .001) and papillary RCC (CE OR, 0.053; 95% CI: 0.02, 0.2; P < .001), and both had substantial interreader agreement (SI, κ = 0.69; CE, κ = 0.71). Poorer performance was observed for chromophobe histology, oncocytomas, and minimal fat angiomyolipomas, (sensitivity range, 14%-67%; specificity range, 97%-99%), with fair to moderate interreader agreement (κ range = 0.23-0.43). Segmental enhancement inversion was an independent predictor of oncocytomas (OR, 16.21; 95% CI: 1.0, 275.4; P = .049), with moderate interreader agreement (κ = 0.49). Conclusion The proposed standardized MR imaging-based diagnostic algorithm had diagnostic accuracy of 81% (88 of 109) and 91% (99 of 109) in the diagnosis of clear cell RCC and papillary RCC, respectively, while achieving moderate to substantial interreader agreement among seven radiologists. © RSNA, 2018 Online supplemental material is available for this article.

PurposeThe detection of small renal masses is increasing with the use of cross-sectional imaging, although many incidental lesions have negligible metastatic potential. Among malignant masses clear cell renal cell carcinoma is the most prevalent and aggressive subtype. A method to identify such histology would aid in risk stratification. Our goal was to evaluate a likelihood scale for multiparametric magnetic resonance imaging in the diagnosis of clear cell histology.Materials and methodsWe retrospectively reviewed the records of patients with cT1a masses who underwent magnetic resonance imaging and partial or radical nephrectomy from December 2011 to July 2015. Seven radiologists with different levels of experience who were blinded to final pathology findings independently reviewed studies based on a predefined algorithm. They applied a clear cell likelihood score, including 1-definitely not, 2-probably not, 3-equivocal, 4-probably and 5-definitely. Binary classification was used to determine the accuracy of clear cell vs all other histologies. Interobserver agreement was calculated with the weighted κ statistic.ResultsA total of 110 patients with 121 masses were identified. Mean tumor size was 2.4 cm and 50% of the lesions were clear cell. Defining clear cell as scores of 4 or greater demonstrated 78% sensitivity and 80% specificity while scores of 3 or greater showed 95% sensitivity and 58% specificity. Interobserver agreement was moderate to good with a mean κ of 0.53.ConclusionsA clear cell likelihood score used with magnetic resonance imaging can reasonably identify clear cell histology in small renal masses and may decrease the number of diagnostic renal mass biopsies. Standardization of imaging protocols and reporting criteria is needed to improve interobserver reliability.

Objective: Renoprotection from reperfusion injury appears to be conferred by HIF-2a activation, which can be stimulated by exogenous acetate administration. The study objective was to assess whether administration of acetate in a porcine model can mitigate kidney injury related to ischemia-reperfusion after renal hilar occlusion. Methods: A porcine single-kidney model was created by performing a laparoscopic nephrectomy followed by animal recovery. After 2 days, the animals underwent laparoscopic hilar dissection. Block randomization was used to assign pigs into one of four experimental groups. One treatment block of pigs received 150 mEq of sodium acetate intravenously during 90 minutes of en bloc occlusion of the renal hilum (herein noted as "cross-clamping"). Another block received 0.75 g/kg of oral sodium acetate for 3 days prior to cross-clamping. A third block received no acetate and underwent hilar dissection without cross-clamping (negative control). The final block received no acetate and underwent cross-clamping (positive control). Serum creatinine was used to estimate renal function post-nephrectomy. Results: A total of 16 animals (4 pigs in each group) completed the study protocol. Median pig weight was 34.6 kg. One pig receiving IV acetate was excluded from the final analysis because of unrecoverable renal failure after cross-clamping. There was a significantly lower mean serum creatinine for the IV acetate group compared with the positive control group 72 hours after cross-clamping (p = 0.012). The same effect was not observed for the pigs receiving oral acetate. By day 7, renal function had recovered without significant difference in all groups. Conclusions: We observed that the administration of intravenous acetate conferred a significant renoprotective benefit in our single kidney ischemia-reperfusion porcine model 72 hours after hilar occlusion. This work is hypothesis-generating, and further work in human subjects undergoing renal hilar occlusion during partial nephrectomy is warranted. [ABSTRACT FROM AUTHOR]