Histological analysis of the kidney tumor-parenchyma interface.

PURPOSE: During enucleative partial nephrectomy excision is performed adjacent to the tumor edge. To better determine the oncologic propriety of enucleative partial nephrectomy we histologically examined the tumor-parenchyma interface. MATERIALS AND METHODS: Archived hematoxylin and eosin stained slides of 124 nephrectomy specimens were rereviewed. We evaluated representative sections of tumor abutting the renal parenchyma and overlying pseudocapsule/perirenal fat were selected at 4 mm(2) sectors apportioned 1, 2, 3 and 4 mm, respectively, from the tumor edge. RESULTS: Median tumor size was 3.5 cm. Of the tumors 111 were malignant (90%) and 119 (96%) had a pseudocapsule with a median thickness of 0.6 mm. Of malignant and benign tumors 82% and 31%, respectively, had an intrarenal pseudocapsule (p < 0.001). Pseudocapsule invasion was noted in 45% of cancers and 15% of benign tumors (p < 0.04). Of pT1a cancers 36% showed intrarenal pseudocapsule invasion. No patient had positive surgical margins. Intrarenal pseudocapsule invasion correlated with clear cell renal cell carcinoma histology but not with cancer size, grade, necrosis or margin width. Inflammation, nephrosclerosis, glomerulosclerosis and arteriosclerosis decreased with increasing distance from the tumor edge. At 1 mm changes were moderate to severe in 38%, 32%, 20% and 17% of tumors while at 5 mm changes were mild in 2.5%, 0.8%, 0.8% and 4%, respectively (p <0.001). Mean arteriolar diameter decreased with tumor proximity (p < 0.0001). CONCLUSIONS: Most renal cancers have an intrarenal pseudocapsule. Partial nephrectomy excision adjacent to the tumor edge appears to be histologically safe. Because 18% of cancers lacked a discernible intrarenal pseudocapsule and 25% of pT1a cancers showed intrarenal pseudocapsule invasion, extreme care is needed to avoid positive margins during enucleative partial nephrectomy.

Juxtatumoral perinephric fat analysis in clear cell renal cell carcinoma.

PURPOSE: The purpose of the study was to evaluate the feasibility of using contrast-enhanced computed tomography (CECT)-based texture analysis (CTTA) metrics to differentiate between juxtatumoral perinephric fat (JPF) surrounding low-grade (ISUP 1-2) versus high-grade (ISUP 3-4) clear cell renal cell carcinoma (ccRCC). METHODS: In this IRB-approved study, we retrospectively queried the surgical database between June 2009 and April 2016 and identified 83 patients with pathologically confirmed ccRCC (low grade: n = 54, mean age = 61.5 years, 18F/35M; high grade n = 30, mean age = 61.7 years, 8F/22M) who also had pre-operative multiphase CT acquisitions. CT images were transferred to a 3D workstation, and nephrographic phase JPF regions were manually segmented. Using an in-house developed Matlab program, a CTTA panel comprising of texture metrics extracted using six different methods, histogram, 2D- and 3D-Gray-level co-occurrence matrix (GLCM) and Gray-level difference matrix (GLDM), and 2D-Fast Fourier Transform (FFT) analyses, was applied to the segmented images to assess JPF textural heterogeneity in low- versus high-grade ccRCC. Univariate analysis and receiver-operator characteristics (ROC) analysis were used to assess interclass differences in texture metrics and their prediction accuracy, respectively. RESULTS: All methods except GLCM consistently revealed increased heterogeneity in the JPF surrounding high- versus low-grade ccRCC. FFT showed increased complexity index (p < 0.01). Histogram analysis showed increased kurtosis and positive skewness in (p < 0.03), and GLDM analysis showed decreased measure of correlation coefficient (MCC) (p < 0.04). Several of the GLCM metrics showed statistically significant (p < 0.04) textural differences between the two groups, but with no consistent trend. ROC analysis showed that MCC in GLCM analysis had an area under the curve of 0.75. CONCLUSIONS: Our study suggests that CTTA of ccRCC shows statistically significant textural differences in JPF surrounding high- versus low-grade ccRCC.

Impact of Renal Hilar Control on Outcomes of Robotic Partial Nephrectomy: Systematic Review and Cumulative Meta-analysis.

CONTEXT: During robotic partial nephrectomy (RPN), various techniques of hilar control have been described, including on-clamp, early unclamping, selective/super-selective clamping, and completely-unclamped RPN. OBJECTIVE: To evaluate the impact of various hilar control techniques on perioperative, functional, and oncological outcomes of RPN for tumors. EVIDENCE ACQUISITION: We conducted a systematic literature review and meta-analysis of all comparative studies on various hilar control techniques during RPN using PubMed, Scopus, and Web of Science according to the Preferred Reporting Items for Systematic Review and Meta-analysis statement, and Methods and Guide for Effectiveness and Comparative Effectiveness Review of the Agency for Healthcare Research and Quality. Cumulative meta-analysis of comparative studies was conducted using Review Manager 5.3. EVIDENCE SYNTHESIS: Of 987 RPN publications in the literature, 19 qualified for this analysis. Comparison of off-clamp versus on-clamp RPN (n=9), selective clamping versus on-clamp RPN (n=3), super selective clamping versus on-clamp RPN (n=5), and early unclamped versus on-clamp (n=3) were reported. Patients undergoing RPN using off-clamp, selective/super selective, or early unclamp techniques had higher estimated blood loss compared with on-clamp RPN (weight mean difference [WMD]: 47.83, p=0.000, WMD: 41.06, p=0.02, and WMD: 37.50, p=0.47); however, this did not seem clinically relevant, since transfusion rates were similar (odds ratio [OR]: 0.98, p=0.95, OR: 0.72, p=0.7, and OR: 1.36, p=0.33, respectively). All groups appeared similar with regards to hospital stay, transfusions, overall and major complications, and positive cancer margin rates. Short- and long-term renal functional outcomes appeared superior in the off-clamp and super selective clamp groups compared with the on-clamp RPN cohort. CONCLUSIONS: Off-clamp, selective/super selective clamp, and early unclamp hilar control techniques are safe and feasible approaches for RPN surgery, with similar perioperative and oncological outcomes compared with on-clamp RPN. Minimizing global renal ischemia may provide superior renal function preservation. However, higher quality data are necessary for definitive conclusions in this regard. PATIENT SUMMARY: The objective of partial nephrectomy is to treat the cancer while maximizing renal function preservation. Clamping the main vessels is done primarily to reduce the blood loss during partial nephrectomy; however, vascular clamping can compromise kidney function. In order to avoid clamping, various techniques have been described. Our analysis showed that techniques that avoid main renal artery clamping during RPN are associated with better renal function preservation, yet deliver non-inferior perioperative and oncological outcomes as compared with RPN procedures that clamp the main vessels.