T2 CLEAR CELL RENAL CELL CARCINOMA IS A RARE ENTITY: A STUDY OF 120 CLEAR CELL RENAL CELL CARCINOMAS

Clear Cell Renal Cell Carcinoma: A Comprehensive Review of its Histopathology, Genetics, and Differential Diagnosis

Clear cell renal cell carcinoma (ccRCC) is the predominant subtype of renal epithelial tumor, accounting for roughly 2% of all malignancies. Clinically, it often presents in the sixth to seventh decade of life, predominantly in men. Pathologically, these tumors exhibit a distinctive golden yellow cut surface, usually arising from the renal cortex. Their microscopic features are characterized by solid and nested architectures of cells with clear or eosinophilic granular cytoplasm and a prominent vascular network. A hallmark genetic feature is the inactivation of the VHL gene situated on chromosome 3p25. The majority of ccRCCs are sporadic (over 95%), typically presenting as a single mass; and a small percentage have a hereditary basis, often associated with VHL disease, characterized by multiple bilateral tumors with an earlier onset. Immunohistochemically, ccRCC tumors express PAX8, CA9 box like pattern, and CD10 but are generally negative for AMACR (35% positive) and KRT7 (15% positive). The prognosis of ccRCC is largely determined by its TNM stage, ISUP/WHO nucleolar grade, and the presence of specific aggressive features. This review article delves into the detailed gross, microscopic, molecular, and clinical features of ccRCC, offering comprehensive insights into its diagnosis, management, and prognosis.

Prognostic evaluation based on radiological morphological characteristic for tumors larger than 7 cm in renal cell carcinoma

PURPOSE

To predict survival prognosis of renal cell carcinoma (RCC) patients with tumors larger than 7 cm by preoperative radiological morphological features.

METHODS

We reviewed the medical records of RCC patients with tumors larger than 7 cm from 2007 to 2017 in Zhongshan Hospital, Fudan University. A total of 251 patients' clinical data were collected. 25 and 9 patients were excluded due to loss of follow-up and lack of imaging data, respectively. PFS and OS from date of surgery were evaluated. We defined the irregularity of the tumor as the morphological feature studied and quantified it according to a theorem of the ellipse: the length from the midpoint of the ellipse to any point on the ellipse is shorter than or equal to 1/2 of the long axis. The cutoff value of irregularity was calculated based on the ROC curve. Cox proportional hazards regression models were used to test associations between features and outcome.

RESULTS

Of all the 217 patients included in the study, 67 patients had disease progression and 30 patients died. The cutoff value of the irregularity was selected to be 0.5335. Adrenal invasion, presence of distant metastasis and irregularity of tumors were significantly associated with PFS, and presence of distant metastasis and irregularity of tumors were significantly associated with OS.

CONCLUSIONS

For patients with tumors larger than 7 cm in RCC, we found a radiological index that is closely related to the prognosis: irregularity. This is an unreported independent prognostic risk factor that can be quantified before surgery.

Clinical utility of histopathology data: urological cancers

Cancer datasets recommend standardised reporting of histopathological data items with elements categorised as either core (required) or non-core (recommended), irrespective of the clinical scenario. However, the clinical significance of a data item in an individual case would depend on the clinicopathological setting as well as local management guidelines. A data item that is critical for patient management in one clinical scenario may be largely irrelevant in another patient. Pathologists must understand how their data are used in clinical practice so that they can focus their limited resources appropriately. We briefly review the use of histopathological data in the management of urological cancers, highlighting scenarios where a data item may be of limited clinical utility.

A CT-based radiomics model for predicting renal capsule invasion in renal cell carcinoma

Background

Renal cell carcinoma (RCC) is a heterogeneous group of kidney cancers. Renal capsule invasion is an essential factor for RCC staging. To develop radiomics models from CT images for the preoperative prediction of capsule invasion in RCC patients.

Methods

This retrospective study included patients with RCC admitted to the Chongqing University Cancer Hospital (01/2011–05/2019). We built a radiomics model to distinguish patients grouped as capsule invasion versus non-capsule invasion, using preoperative CT scans. We evaluated effects of three imaging phases, i.e., unenhanced phases (UP), corticomedullary phases (CMP), and nephrographic phases (NP). Five different machine learning classifiers were compared. The effects of tumor and tumor margins are also compared. Five-fold cross-validation and the area under the receiver operating characteristic curve (AUC) are used to evaluate model performance.

Results

This study included 126 RCC patients, including 46 (36.5%) with capsule invasion. CMP exhibited the highest AUC (AUC = 0.81) compared to UP and NP, when using the forward neural network (FNN) classifier. The AUCs using features extracted from the tumor region were generally higher than those of the marginal regions in the CMP (0.81 vs. 0.73) and NP phase (AUC = 0.77 vs. 0.76). For UP, the best result was obtained from the marginal region (AUC = 0.80). The robustness analysis on the UP, CMP, and NP achieved the AUC of 0.76, 0.79, and 0.77, respectively.

Conclusions

Radiomics features in renal CT imaging are associated with the renal capsule invasion in RCC patients. Further evaluation of the models is warranted.

New developments in existing WHO entities and evolving molecular concepts: The Genitourinary Pathology Society (GUPS) update on renal neoplasia

The Genitourinary Pathology Society (GUPS) reviewed recent advances in renal neoplasia, particularly post-2016 World Health Organization (WHO) classification, to provide an update on existing entities, including diagnostic criteria, molecular correlates, and updated nomenclature. Key prognostic features for clear cell renal cell carcinoma (RCC) remain WHO/ISUP grade, AJCC/pTNM stage, coagulative necrosis, and rhabdoid and sarcomatoid differentiation. Accrual of subclonal genetic alterations in clear cell RCC including SETD2, PBRM1, BAP1, loss of chromosome 14q and 9p are associated with variable prognosis, patterns of metastasis, and vulnerability to therapies. Recent National Comprehensive Cancer Network (NCCN) guidelines increasingly adopt immunotherapeutic agents in advanced RCC, including RCC with rhabdoid and sarcomatoid changes. Papillary RCC subtyping is no longer recommended, as WHO/ISUP grade and tumor architecture better predict outcome. New papillary RCC variants/patterns include biphasic, solid, Warthin-like, and papillary renal neoplasm with reverse polarity. For tumors with 'borderline' features between oncocytoma and chromophobe RCC, a term "oncocytic renal neoplasm of low malignant potential, not further classified" is proposed. Clear cell papillary RCC may warrant reclassification as a tumor of low malignant potential. Tubulocystic RCC should only be diagnosed when morphologically pure. MiTF family translocation RCCs exhibit varied morphologic patterns and fusion partners. TFEB-amplified RCC occurs in older patients and is associated with more aggressive behavior. Acquired cystic disease (ACD) RCC-like cysts are likely precursors of ACD-RCC. The diagnosis of renal medullary carcinoma requires a negative SMARCB1 (INI-1) expression and sickle cell trait/disease. Mucinous tubular and spindle cell carcinoma (MTSCC) can be distinguished from papillary RCC with overlapping morphology by losses of chromosomes 1, 4, 6, 8, 9, 13, 14, 15, and 22. MTSCC with adverse histologic features shows frequent CDKN2A/2B (9p) deletions. BRAF mutations unify the metanephric family of tumors. The term "fumarate hydratase deficient RCC" ("FH-deficient RCC") is preferred over "hereditary leiomyomatosis and RCC syndrome-associated RCC". A low threshold for FH, 2SC, and SDHB immunohistochemistry is recommended in difficult to classify RCCs, particularly those with eosinophilic morphology, occurring in younger patients. Current evidence does not support existence of a unique tumor subtype occurring after chemotherapy/radiation in early childhood.

Update on the Role of Imaging in Clinical Staging and Restaging of Renal Cell Carcinoma Based on the AJCC 8th Edition, From the AJR Special Series on Cancer Staging

This article reviews the essential role of imaging in clinical staging and restaging of renal cell carcinoma (RCC). To completely characterize and stage an indeterminate renal mass, renal CT or MRI without and with IV contrast administration is recommended. The critical items for initial clinical staging of an indeterminate renal mass or of a known RCC according to the TNM staging system are tumor size, renal sinus fat invasion, urinary collecting system invasion, perinephric fat invasion, venous invasion, adrenal gland invasion, invasion of the perirenal (Gerota) fascia, invasion into other adjacent organs, the presence of enlarged or pathologic regional (retroperitoneal) lymph nodes, and the presence of distant metastatic disease. Larger tumor size is associated with higher stage disease and invasiveness, lymph node spread, and distant metastatic disease. Imaging practice guidelines for clinical staging of RCC, as well as the role of renal mass biopsy, are highlighted. Specific findings associated with response of advanced cancer to antiangiogenic therapy and immunotherapy are discussed, as well as limitations of changes in tumor size after targeted therapy. The accurate clinical staging and restaging of RCC using renal CT or MRI provides important prognostic information and helps guide the optimal management of patients with RCC.

[Criteria for an improved prognostic stratification in category pT renal carcinoma]

Asymptomatic renal carcinomas are usually small and localized and thus, for the assessment of pT, precise criteria are required, able to identify the initial phases of a local extension and correlate them with current prognostic prospects. Various studies and consensus meetings have defined precisely how to measure tumoral nodules (solid, cystic and multiple). Furthermore, they have distinguished tumoral extension to the renal sinus, which has a worse prognosis, from that to the perirenal adipose tissue. They have also analyzed the clinical significance of invasion of the sinus vessels, the hilar veins and parenchymal vascular retroinvasion. Our aim is to revise and update the criteria of the different pT subcategories and consider those morphological aspects which could be clinically significant and that are not currently included in the TNM classification.

Computed tomography features predicting aggressiveness of malignant parenchymal renal tumors suitable for partial nephrectomy

The aim of this study was to identify and standardize computed tomography (CT) features having a potential role in predicting aggressiveness of malignant parenchymal renal tumors suitable for partial nephrectomy (PN). We performed a non-systematic review of the recent literature to evaluate the potential impact of CT variables proposed by the Society of Abdominal Radiology Disease-Focused Panel on Renal Cell Carcinoma in predicting aggressiveness of newly diagnosed malignant parenchymal renal tumors. The analyzed variables were clinical tumor size, tumor growth rate, enhancement characteristics, amount of cystic component, polar and capsular location, tumor margins and distance between tumor and renal sinus. Unfavorable behavior was defined as: 1) renal cell carcinoma (RCC) with stage ≥pT3; 2) nuclear grade 3 or 4; 3) presence of sarcomatoid de-differentiation; or 4) non-clear cell subtypes with unfavorable prognosis (type 2 papillary RCC, collecting duct or renal medullary carcinoma, unclassified RCC). Beyond clinical tumor size, tumor growth rate, enhancement characteristics, amount of cystic component, tumor margins and distance between tumor and renal sinus are highly relevant features predicting an unfavorable behavior. Moreover, several studies supported the role of necrosis as preoperative predictor of tumor aggressiveness. Peritumoral and intratumoral vasculature as well as capsule status are emerging variables that need to be further evaluated. Tumor size, enhancement characteristics, tumor margins and distance to the renal sinus are highly relevant CT features predicting biological aggressiveness of malignant parenchymal renal tumors. Combination of these parameters might be useful to generate tools to predict the unfavorable behavior of renal tumors suitable for PN.

Comparison of T2N0M0 and T3aN0M0 in Predicting the Prognosis of Patients With Renal Cell Carcinoma

Background: To investigate the prognostic role of tumor size in patients with pathological T2N0M0 and T3aN0M0 renal cell carcinoma (RCC) treated by radical surgery. Methods: A total of 3,662 cases were retrospectively analyzed from the Surveillance, Epidemiology and End Results (SEER) from 2010 to 2012. Overall survival (OS) and cancer-specific survival (CSS) data were obtained. The log-rank test was used to compare survival distributions and Cox proportional hazards model was used for univariate and multivariate analyses, respectively. Results: In the low-risk T3aN0M0 (perinephric fatty infiltration or sinus fatty infiltration only) group, patients with tumor size ≤ 7 cm were associated with a better OS (P = 0.009) and CSS (P < 0.001) than those with tumor size >7 cm. However, there was no difference in OS (P = 0.129) and CSS (P = 0.539) between T2bN0M0 patients and low-risk T3aN0M0 patients with tumor size ≤ 7 cm. A new T classification grouping patients with both T2bN0M0 and T3aN0M0 with tumor diameter ≤ 7 cm into the same staging category (pT2aN0M0, pT2bN0M0+low-risk pT3aN0M0 [tumor diameter ≤ 7cm], low-risk pT3aN0M0 [tumor diameter >7 cm], high-risk pT3aN0M0) was proposed and it was found as an independent predictive variable for OS and CSS. Conclusions: Findings from the present study suggest that the reclassification of pT2N0M0 and pT3aN0M0 RCC can lead to better prediction of OS and CSS.

Nephron-Sparing Surgery for Adult Xp11.2 Translocation Renal Cell Carcinoma at Clinical T1 Stage: A Multicenter Study in China

Purpose

To evaluate the oncologic efficacy and feasibility of nephron-sparing surgery (NSS) in adult Xp11.2 translocation renal cell carcinoma (RCC).

Patients and Methods

Seventy patients with Xp11.2 translocation RCC and 273 with conventional RCC from five institutions in Nanjing were retrospectively studied. All patients were older than 18 years and were categorized into clinical T1 (cT1) stage using preoperative imaging. Using the preoperative imaging and electronic medical records, anatomical and pathological features were collected and analyzed.

Results

Among patients with Xp11.2 translocation RCC, 18/36 (50.0%) with cT1a and 12/34 (35.3%) with cT1b tumors underwent NSS. The respective proportions in the conventional RCC group were 121/145 (83.4%) and 93/128 (72.7%). Among cT1a tumors, the Xp11.2 translocation RCCs tended to be adjacent to the collecting system, sinus, and axial renal midline compared with conventional RCCs. Patients with Xp11.2 translocation RCCs who underwent NSS had comparable progression-free survival (PFS) and overall survival to radical nephrectomy (RN) patients (P > 0.05). Among cT1b tumors, surgical margin positivity and pelvicalyceal, vascular, and region lymphatic involvement were more likely to occur in the Xp11.2 translocation RCCs (P < 0.05). Patients with Xp11.2 translocation RCC who underwent RN had a more favorable PFS than those who underwent NSS (P = 0.048). However, multivariate analysis of PFS did not identify surgical method as a risk factor (P = 0.089).

Conclusions

Among adults with Xp11.2 translocation RCC, NSS can be an alternative for patients with cT1a tumor but should be performed with more deliberation in patients with cT1b tumors.

Electronic supplementary material

The online version of this article (10.1245/s10434-020-08813-y) contains supplementary material, which is available to authorized users.

Data set for the reporting of carcinoma of renal tubular origin: recommendations from the International Collaboration on Cancer Reporting (ICCR)

AIMS

The International Collaboration on Cancer Reporting (ICCR) has provided detailed data sets based upon the published reporting protocols of the Royal College of Pathologists, the Royal College of Pathologists of Australasia and the College of American Pathologists.

METHODS AND RESULTS

The data set for carcinomas of renal tubular origin treated by nephrectomy was developed to provide a minimum structured reporting template suitable for international use, and incorporated recommendations from the 2012 Vancouver Consensus Conference of the International Society of Urological Pathology (ISUP) and the fourth edition of the World Health Organisation Bluebook on tumours of the urinary and male genital systems published in 2016. Reporting elements were divided into those, which are required and recommended components of the report. Required elements are: specimen laterality, operative procedure, attached structures, tumour focality, tumour dimension, tumour type, WHO/ISUP grade, sarcomatoid/rhabdoid morphology, tumour necrosis, extent of invasion, lymph node status, surgical margin status, AJCC TNM staging and co-existing pathology. Recommended reporting elements are: pre-operative treatment, details of tissue removed for experimental purposes prior to submission, site of tumour(s) block identification key, extent of sarcomatoid and/or rhabdoid component, extent of necrosis, presence of tumour in renal vein wall, lymphovascular invasion and lymph node status (size of largest focus and extranodal extension).

CONCLUSIONS

It is anticipated that the implementation of this data set in routine clinical practice will inform patient treatment as well as provide standardised information relating to outcome prediction. The harmonisation of data reporting should also facilitate international research collaborations.

Renal cell carcinoma staging: pitfalls, challenges, and updates

Renal cell carcinoma (RCC) is unusual among cancers in that it often grows as a spherical, well-circumscribed mass. Increasing tumour size influences the pathological pT stage category within pT1 and pT2, with cutoffs of 40, 70 and 100 mm; however, with increasing size also comes a sharp increase in the likelihood of renal sinus or renal vein tributary invasion, such that clear cell RCC rarely reaches 70 mm without invading one of these. To clarify some previous challenges in assigning tumour stage, the American Joint Committee on Cancer 2016 tumor-node-metastasis classification has removed the requirements than vein invasion be recognised grossly and that vein walls contain muscle for the diagnosis of vein invasion. Renal pelvis invasion has also been added as an additional route to pT3a. Multinodularity or finger-like extensions from a renal mass should be viewed with great suspicion for the possibility of vein or renal sinus invasion, and, as tumour size increases to over 40-50 mm, thorough sampling of the renal sinus interface should always be undertaken. With increasing interest in adjuvant therapy in renal cancer, the pathologist's role in RCC staging will continue to be an important prognostic parameter and a tool for selection of patients for enrolment in clinical trials.

WHO/ISUP classification, grading and pathological staging of renal cell carcinoma: standards and controversies

PURPOSE

Pathological parameters assessed on biopsies and resection specimens have a pivotal role in the diagnosis, prognosis and management of patients with renal cell carcinoma (RCC).

METHODS

A non-systematic literature search was performed, updated to January 2018, to identify key standards and controversies in the pathological classification, grading and staging of RCC.

RESULTS

Although most RCCs exhibit characteristic morphology that enables easy categorisation, RCCs show considerable morphological heterogeneity and it is not uncommon for there to be difficulty in assigning a tumour type, especially with rarer tumour subtypes. The differentiation between benign and malignant oncocytic tumours remains a particular challenge. The development of additional immunohistochemical and molecular tests is needed to facilitate tumour typing, because of the prognostic and therapeutic implications, and to enable more reliable identification of poorly differentiated metastatic tumours as being of renal origin. Any new tests need to be applicable to small biopsy samples, to overcome the heterogeneity of renal tumours. There is also a need to facilitate identification of tumour types that have genetic implications, to allow referral and management at specialist centres. Digital pathology has a potential role in such referral practice.

CONCLUSION

Much has been done to standardise pathological assessment of renal cell carcinomas in recent years, but there still remain areas of difficulty in classification and grading of these heterogeneous tumours.

Multislice spiral computed tomography signs of invasion of the renal capsule by renal cell carcinoma

Capsular invasion is frequently detected in localized renal cell carcinoma (RCC) specimens and is associated with a poor prognosis, but the pretreatment imaging features are poorly known. This study aimed to explore the positions and margin types of RCC and various computed tomography (CT) signs, as well as the correlations with the presence/absence of RCC invasion of the renal capsule.This was a retrospective study of 158 consecutive patients treated for pathologically confirmed RCC between January 2013 and December 2016 at the Nantong University Affiliated Hospital. The patients were divided into the capsule invasion and noninvasion groups. The CT signs were analyzed (position type, margin type, and CT findings in the perirenal fat).There were 92 (58.2%) men and 66 (41.8%) women; mean age was 59.1 ± 12.8. Renal capsule invasion was confirmed in 45 cases. There was no difference in the position types between the 2 groups (all P > .05). The smooth margin was more common in the noninvasion group (53.1% vs 15.6%, P < .01). The deep lobulated type and the saw tooth sign were more common in the invasion group (57.8% vs 7.1%; and 40.0% vs 6.2%; both P < .01). The deep lobulated (OR = 2.03, 95%CI: 1.21-3.39, P = .007) and saw tooth (OR = 1.036, 95%CI: 1.008-1.065, P = .011) signs were independently associated with renal capsule invasion.Smooth tumor margin suggests the absence of renal capsule invasion, while the deep lobulated and the saw tooth signs strongly suggest the presence of renal capsule invasion in patients with RCC.

Magnetic resonance imaging (MRI) of the renal sinus

This article presents methods to improve MR imaging approach of disorders of the renal sinus which are relatively uncommon and can be technically challenging. Multi-planar Single-shot T2-weighted (T2W) Fast Spin-Echo sequences are recommended to optimally assess anatomic relations of disease. Multi-planar 3D-T1W Gradient Recalled Echo imaging before and after Gadolinium administration depicts the presence and type of enhancement and relation to arterial, venous, and collecting system structures. To improve urographic phase MRI, concentrated Gadolinium in the collecting systems should be diluted. Diffusion-Weighted Imaging (DWI) should be performed before Gadolinium administration to minimize T2* effects. Renal sinus cysts are common but can occasionally be confused for dilated collecting system or calyceal diverticula, with the latter communicating with the collecting system and filling on urographic phase imaging. Vascular lesions (e.g., aneurysm, fistulas) may mimic cystic (or solid) lesions on non-enhanced MRI but can be suspected by noting similar signal intensity to the blood pool and diagnosis can be confirmed with MR angiogram/venogram. Multilocular cystic nephroma commonly extends to the renal sinus, however, to date are indistinguishable from cystic renal cell carcinoma (RCC). Solid hilar tumors are most commonly RCC and urothelial cell carcinoma (UCC). Hilar RCC are heterogeneous, hypervascular with epicenter in the renal cortex compared to UCC which are centered in the collecting system, homogeneously hypovascular, and show profound restricted diffusion. Diagnosis of renal sinus invasion in RCC is critically important as it is the most common imaging cause of pre-operative under-staging of disease. Fat is a normal component of the renal sinus; however, amount of sinus fat correlates with cardiovascular disease and is also seen in lipomatosis. Fat-containing hilar lesions include lipomas, angiomyolipomas, and less commonly other tumors which engulf sinus fat. Mesenchymal hilar tumors are rare. MR imaging diagnosis is generally not possible, although anatomic relations should be described to guide diagnosis by percutaneous biopsy or surgery.

Chromophobe Renal Cell Carcinoma With Retrograde Venous Invasion and Gain of Chromosome 21: Potential Harbingers of Aggressive Clinical Behavior

Occasionally, renal cell carcinoma (RCC) with renal vein extension spreads against the flow of blood within vein branches into the kidney, forming multifocal nodules throughout the renal parenchyma. These foci are not regarded as multiple tumors but rather reverse spread of tumor along the venous system. This intravascular spread has previously been reported in clear cell RCC and RCC unclassified. However, to our knowledge, this has never been reported in chromophobe RCC. Chromophobe RCC is a unique histologic subtype of renal cancer, generally thought to have less aggressive behavior. However, it nonetheless has the potential to undergo sarcomatoid dedifferentiation, which is associated with poor prognosis. We report a unique case of a 65-year-old man with chromophobe RCC (pT3a) showing classic morphology (nonsarcomatoid), yet presenting with retrograde venous invasion and hilar lymph node metastasis at the time of right radical nephrectomy. Fluorescence in situ hybridization revealed gain of chromosome 21 with loss of multiple other chromosomes. Partial hepatectomy was performed to resect metastatic RCC 7 months after nephrectomy, revealing chromophobe RCC with classic morphology. Bone biopsy confirmed skeletal metastases 38 months after initial diagnosis. Although invasion of the renal vein and retrograde venous invasion are characteristically seen in clear cell RCC, this unusual phenomenon may also occur in chromophobe RCC, despite its unique tumor biology. This and gain of chromosome 21, which was postulated to be associated with aggressive behavior in a previous report, were associated with adverse behavior in our patient, who had short-term progression to multi-organ metastatic disease.

Factors associated with postoperative renal sinus invasion and perinephric fat invasion in renal cell cancer: treatment planning implications

In patients with renal cell carcinoma (RCC), postoperative upstaging including perinephric fat invasion (PNI) and renal sinus invasion (RSI) leads to unfavorable oncological outcomes. Determining the preoperative risk factors for postoperative upstaging could be beneficial for treatment planning. In this study, 267 RCC patients who underwent radical nephrectomy were studied retrospectively. The RSI incidence was significantly greater than that of PNI. Kaplan-Meier analysis revealed that patients with RSI, PNI, and RSI plus PNI had poorer disease-free-survival than those with neither RSI nor PNI. Univariate and multivariate logistic regression analyses indicated that a tumor extension into the sinus, an irregular tumor-sinus border, and an irregular tumor shape in CT/MRI imaging were independent risk factors for RSI. And a tumor larger than 5 cm, an irregular tumor-perinephric fat border, and a tumor necrosis were independent risk factors for PNI. Subgrouping of patients into low-, moderate-, and high-risk groups according to these factors, revealed a direct association between the risk factors and PNI/RSI incidence. In conclusion, in patients with RCC, preoperative risk factors associated with postoperative upstaging could be assessed by imaging data obtained using CT or MRI. Preoperative Risk group classification would be clinically useful for patient counseling and treatment planning.

[WHO classification 2016 and first S3 guidelines on renal cell cancer: What is important for the practice?]

The first S3 guidelines on renal cell cancer cover the practical aspects of imaging, diagnostics and therapy as well as the clinical relevance of pathology reporting. This review summarizes the changes in renal tumor classification and the new recommendations for reporting renal cell tumors. The S3 guidelines recommend the 2016 World Health Organization (WHO) classification of renal cell tumors. Novel renal cell tumor entities and provisional or emerging renal cell tumor entities of the 2016 WHO classification of renal tumors are discussed. The S3 guidelines for renal cell cancer also recommend the use of the WHO/International Society of Urologic Pathology (ISUP) grading system for clear cell and for papillary renal cell carcinomas, which replaces the previously used Fuhrman grading system.

The Difference in Prognosis between Renal Sinus Fat and Perinephric Fat Invasion for pT3a Renal Cell Carcinoma: A Meta-Analysis

Background

In the current Tumour-Node-Metastasis (TNM) classification system for renal cell carcinoma (RCC), both renal sinus fat invasion (SFI) and perinephric fat invasion (PFI) are defined as T3a, suggesting that the prognosis should be similar for the two pathologic findings. Several studies, however, have reported a worse prognosis for SFI in patients with a T3a tumor. In order to compare the prognosis of these two pathologic findings (SFI versus. PFI) in a more comprehensive way, this meta-analysis was performed.

Methods

To identify relevant studies, Medline, Embase, Cochrane Library, and Scopus database were searched from the inception until October 2014. A meta-analysis was performed using Review Manager 5.2 and STATA 11. Pooled Odds ratio (OR) and/or hazard ratio (HR) with 95% confidence interval (CI) were calculated to examine the risk or hazard association.

Results

A total of 6 studies including 1031 patients qualified for analysis. T3a RCC patients with SFI were significantly associated with poor cancer specific survival(CSS) (HR: 1.47, 95% CI: 1.19–1.83; P<0.001) compared to those with PFI. In T3aNx/N0M0 subgroup, SFI patients also showed a worse prognosis than those with PFI (CSS, HR: 1.94, 95% CI: 1.21–3.12; P = 0.006). T3a RCC patients with SFI had higher Furhman grade, greater possibility of lymph node metastasis, sarcomatoid differentiation and tumour necrosis. Main limitation is the relatively small number of included studies.

Conclusion

The present meta-analysis suggested that SFI is associated with worse CSS in patients with pT3a RCC. However, due to the small number of included studies, future studies with a large sample size are required to further verify our findings.

Correcting the Shrinkage Effects of Formalin Fixation and Tissue Processing for Renal Tumors: toward Standardization of Pathological Reporting of Tumor Size

Given the importance of correctly staging renal cell carcinomas, specific guidelines should be in place for tumor size measurement. While a standard means of renal tumor measurement has not been established, intuitively, tumor size should be based on fresh measurements. We sought to assess the accuracy of postfixation and microscopic measurements of renal tumor size, as compared to fresh measurements and radiographic size. Thirty-four nephrectomy cases performed by a single surgeon were prospectively measured at different time points. The study cases included 23 clear cell renal cell carcinomas, 6 papillary renal cell carcinomas, and 5 other renal tumors. Radiologic tumors were 12.1% larger in diameter than fresh tumors (P<0.01). Furthermore, fresh specimens were 4.6% larger than formalin-fixed specimens (P<0.01), and postfixation measurements were 7.1% greater than microscopic measurements (P<0.01). The overall mean percentage of shrinkage between fresh and histological specimens was 11.4% (P<0.01). Histological processing would cause a tumor stage shift from pT1b to pT1a for two tumors in this study. The shrinkage effects of formalin fixation and histological processing may result in understaging of renal cell carcinomas. The shrinkage factor should be considered when reporting tumor size.

Pathological Stage T3a Significantly Increases Disease Recurrence across All Tumor Sizes in Renal Cell Carcinoma

PURPOSE

Tumor size and stage are important prognostic parameters in renal cell carcinoma. While pathological stage T1 and T2 are defined by size alone, the presence of certain intrinsic features can up stage a tumor to pathological stage T3a regardless of size. We investigate the effect of pathological tumor stage on the relationship between tumor size and risk of disease recurrence.

MATERIALS AND METHODS

Data were reviewed on patients who underwent nephrectomy at our institution between 2006 and 2013 to identify all those with pathological stage T1, T2 and T3a tumors. A proportional hazards Cox model was built with time to recurrence as outcome, and pathological stage and tumor size as covariates. An interaction term for stage and tumor size was included.

RESULTS

The final cohort included 1,809 patients. On multivariable analysis, when adjusted for tumor size, patients with pT3a tumors had a greater risk of tumor recurrence compared to those with pT1/T2 tumors (HR 3.70; 95% CI 2.31, 5.92; p <0.0001). The risk of disease recurrence increased more rapidly as tumor size increased only with the presence of perinephric fat invasion (p=0.006).

CONCLUSIONS

Using the AJCC 2010 staging criteria we validated pathological stage T3a as a poor prognostic factor in renal cell carcinoma regardless of tumor size. Our results also demonstrated an increased rate of risk of recurrence with perinephric fat invasion. Given this increased risk of recurrence, even in tumors less than 4 cm, closer surveillance is warranted in such cases and the role of perinephric involvement necessitates further investigation.

The ISUP system of staging, grading and classification of renal cell neoplasia

There have been significant changes in the staging, classification and grading of renal cell neoplasia in recent times. Major changes have occurred in our understanding of extra-renal extension by renal cell cancer and how gross specimens must be handled to optimally display extra-renal spread. Since the 1981 World Health Organization (WHO) classification of renal tumors, in which only a handful of different entities were reported, many new morphological types have been described in the literature, resulting in 50 different entities reported in the 2004 WHO classification. Since 2004, further new entities have been recognized and reported necessitating an update of the renal tumor classification. There have also been numerous grading systems for renal cell carcinoma with Fuhrman grading, the most widely used system. In recent times, the prognostic value and the applicability of the Fuhrman grading system in practice has been shown to be, at best, suboptimal. To address these issues and to recommend reporting guidelines, the International Society of Urological Pathology (ISUP) undertook a review of adult renal neoplasia through an international consensus conference in Vancouver in 2012. The conduct of the conference was based upon evidence from the literature and the current practice amongst recognized experts in the field. Working groups selected to deal with key topics evaluated current data and identified points of controversy. A pre-meeting survey of the ISUP membership was followed by the consensus conference at which a formal ballot was taken on each key issue. A 65% majority vote was taken as consensus. This review summarizes the outcome and recommendations of this conference with regards to staging, classification and grading of renal cell neoplasia.

Biomarkers in renal cancer

Treatment options for primary and metastatic renal cancer are increasing. Accurate data from the pathological examination of renal cancer specimens aid clinicians in stratifying patients for surveillance and adjuvant therapies. This review focuses on biomarkers in diagnosis, prognosis and prediction of the biologic behavior of renal tumors which should be recorded in pathology reports and which are under investigation. Special emphasis is given to the use of immunohistochemical markers in differential diagnosis of various renal tumor subtypes. The relevance of cytogenetic and molecular findings is also discussed. The review includes the 2012 International Society for Urological Pathology Consensus conference recommendations.

Role of CT in the assessment of muscular venous branch invasion in patients with renal cell carcinoma

OBJECTIVE

The purpose of this article is to determine whether the relationship between a renal cell carcinoma and the renal sinus fat on contrast-enhanced CT could predict muscular venous branch invasion and the type of surgery needed.

MATERIALS AND METHODS

A total of 115 consecutive patients underwent pre-operative contrast-enhanced CT between August 2011 and December 2011. Without access to histopathologic information, on nephrographic phase contrast-enhanced CT images, two radiologists independently determined whether the renal tumor was in contact with the renal sinus fat or separated from the renal sinus fat. Interreader agreements and performance characteristics of imaging tests were calculated, and histopathologic analysis served as the standard of reference.

RESULTS

Histopathologic analysis identified 115 renal tumors, 90% (103/115) of which were renal cell carcinomas. Thirty-nine percent (31/80) of renal cell carcinomas that abutted the renal sinus fat on CT displayed muscular venous branch invasion on histopathologic analysis. Patients with renal cell carcinomas separated from the renal sinus fat were more likely to undergo partial nephrectomies (96% [22/23]; p = 0.013). Sensitivity and specificity for the identification of muscular venous branch invasion on CT were 94% (95% CI, 80-99%) and 30% (20-42%), respectively. Interreader agreement of visual assessment was excellent (κ = 0.87; 95% CI, 0.81-0.92).

CONCLUSION

If a renal cell carcinoma was separated from the renal sinus fat on CT, the likelihood of muscular venous branch invasion being identified by histopathologic analysis was significantly decreased, and the patient was more likely to undergo a partial nephrectomy.

Growth pattern, an important pathologic prognostic parameter for clear cell renal cell carcinoma

OBJECTIVES

To assess the validity of growth pattern as a unique prognostic parameter for clear cell renal cell carcinoma (ccRCC).

METHODS

In total, 561 patients with pathologic tumor stage 1 (pT1), pT2, and pT3a ccRCC without preoperative metastasis were evaluated. Clinicopathologic parameters, including pathologic tumor stage, Fuhrman grade, tumor necrosis, lymphovascular invasion, and growth pattern, were analyzed to predict disease-free survival (DFS) and cancer-specific survival (CSS).

RESULTS

Growth patterns were defined as follows: expansive included tumors with well-circumscribed margins without normal renal tissue in the tumor, and infiltrative involved tumors with ill-circumscribed margins or normal renal tissue in the tumors. In multivariate analysis, Fuhrman grade, tumor necrosis, and growth pattern were useful predictors of DFS, whereas Fuhrman grade and growth pattern were useful predictors of CSS, although only 30 cases showed the infiltrative pattern.

CONCLUSIONS

Growth pattern can be considered a new prognostic parameter for ccRCC.

An overview of renal cell cancer: pathology and genetics

Renal cell carcinoma is a group of malignancies arising from the epithelium of the renal tubules. The pattern of somatic mutations in kidney tumors has been extensively investigated. In the current 2004 WHO classification, the molecular background of a renal tumor has become, in addition to histopathology, a major criterion for tumor classification. The goal of this review is to discuss morphology and genetics of adult renal epithelial cancer included in the 2004 WHO classification and to mention renal tumor types, which are not considered in the current WHO classification. Further, pathologic considerations with clinical and prognostic implications are provided.

Validation of the 2009 TNM Classification for Renal Cell Carcinoma: Comparison with the 2002 TNM Classification by Concordance Index

PURPOSE

To assess the validity of the 2009 TNM classification for renal cell carcinoma (RCC) and compare its ability to predict survival relative to the 2002 classification.

MATERIALS AND METHODS

We identified 1,691 patients who underwent radical nephrectomy or partial nephrectomy for unilateral, sporadic RCC between 1989 and 2007. Cancer-specific survival was estimated by the Kaplan-Meier method and was compared among groups by the log-rank test. Associations of the 2002 and 2009 TNM classifications with death from RCC were evaluated by Cox proportional hazards regression models. The predictive abilities of the two classifications were compared by using Harrell's concordance (c) index.

RESULTS

There were 234 deaths from RCC a mean of 38 months after nephrectomy. According to the 2002 primary tumor classification, 5-year cancer-specific survival was 97.6% in T1a, 92.0% in T1b, 83.3% in T2, 61.9% in T3a, 51.1% in T3b, 40.0% in T3c, and 33.6% in T4 (p for trend<0.001). According to the 2009 classification, 5-year cancer-specific survival was 83.2% in T2a, 83.8% in T2b, 62.6% in T3a, 41.1% in T3b, 50.0% in T3c, and 26.1% in T4 (p for trend<0.001). The c index for the 2002 primary tumor classification was 0.810 in the univariate analysis and increased to 0.906 in the multivariate analysis. The c index for the 2009 primary tumor classification was 0.808 in the univariate analysis and increased to 0.904 in the multivariate analysis.

CONCLUSIONS

Our data suggest that the predictive ability the 2009 TNM classification is not superior to that of the 2002 classification.

Advances and controversies in grading and staging of renal cell carcinoma

Despite the considerable progress made in our understanding of the pathogenesis, genetics, and pathology of renal cell carcinoma (RCC), difficulties remain relating to the prediction of clinical outcome for individual cases. Although there is evidence to show that high-grade tumors have a poorer prognosis when compared to those of low grade, debate remains regarding the predictive value of grading, especially for those tumors classified into the intermediate grades. Numerous composite morphologic and nuclear grading systems have been proposed for RCC and although that of the Fuhrman classification have achieved widespread usage, the validity of the grading criteria of this classification has been questioned. In addition, there are few studies that have attempted to validate the Fuhrman system for RCCs beyond that of the clear cell subtype. Recent studies have indicated that grading of papillary RCC should be based on nucleolar prominence alone and that the components of the Fuhrman grading classification do not provide prognostic information for chromophobe RCC. Independent of tumor grade, the prognostic importance of tumor stage for RCC is well recognized. The Union Internationale Contre le Cancer/American Joint Committee for Cancer Staging and End Results Reporting TNM staging system is now in its sixth edition (2002) and recent refinements have focused on defining size cut points that will identify apparently localized tumors that will develop recurrence and/or metastases despite attempted curative surgery. In parallel with these studies it has been shown that infiltration of the renal sinus is an important prognostic factor, being observed in almost all tumors >7 cm in diameter. Questions remain as to the appropriate stratification of regional extension of RCC, as defined in the T3 tumor-staging category. Recent modifications to this category have been suggested combining the level of infiltration of the venous outflow tract with the presence or absence of infiltration of the adrenal gland and/or perirenal fat. Similarly, the utility of classifying lymph node involvement by tumor is debated, although it is well recognized that lymph node infiltration is associated with a poor prognosis. Although the current TNM classification does provide useful prognostic information it would appear that further modifications are justified to enhance the predictive value of staging for RCC.

Pathologic Features of Adult Renal Cortical Tumors

In the past few years, a much better understanding of the morphologic spectrum of renal cortical tumors has resulted in a clinically highly relevant contemporary classification system of these tumors. The current and still evolving era of targeted therapies in kidney cancer further highlights the importance of the appropriate pathologic classification. The recently gained knowledge about molecular-driven antigen expression almost certainly will have a major role to play in the characterization, development, and evaluation of targeted therapies in kidney cancer in the future.

Epidemiology, clinical staging, and presentation of renal cell carcinoma

The increasing incidence of renal cell carcinoma over the past 2 decades can be partly explained by the expanding use of abdominal imaging. As a result, the most incident renal cancers today are small, localized, and asymptomatic. However, the well-documented rise in all stages of RCC calls into question the nature of these asymptomatic lesions. The expected "screening effect" of detecting RCC when it is small and localized, with subsequent decreases in disease-specific mortality, has not been observed. Disease-specific mortality is actually rising, especially in African American patients. Effective interventions aimed at reducing obesity, hypertension, and smoking may help in reducing the incidence of RCC in the future.

Perinephric and renal sinus fat infiltration in pT3a renal cell carcinoma: possible prognostic differences

OBJECTIVE

To evaluate the influence of perinephric (PN) and renal sinus (RS) fat infiltration on cancer-specific survival beyond other prognostic factors, as the Tumour-Node-Metastasis (TNM) classification system defines stage T3a renal cell carcinoma (RCC) as infiltration of perirenal fat and/or direct infiltration of the adrenal gland. Perirenal fat invasion is differentiated into RS and PN fat infiltration, but not further classified for the prognosis.

PATIENTS AND METHODS

From 1990 to October 2007 106 patients with advanced RCC (T3a) were followed prospectively at one academic centre; all had a radical nephrectomy. To identify prognostic effects of PN, RS or RS + PN fat infiltration, univariable and multivariable Cox proportional hazard regression models were applied, including lymph node status, metastases, presence of sarcomatoid features and tumour necrosis, Fuhrman's grade, Karnofsky performance status, and tumour size.

RESULTS

PN fat invasion alone was present in 58, RS in 21, and PN + RS in 27 patients. The median follow-up was 2.9 years; 49 patients died from RCC. In univariable and multivariable analyses RS fat infiltration was an unfavourable prognostic factor (adjusted hazard ratio, HR, 2.24, P = 0.019). Univariable analysis of RS + PN fat infiltration showed the worst prognostic effect (HR 3.25, P < 0.001). In multivariable analysis this combination was an independent prognostic factor (HR 2.75, P = 0.007), as was the presence of metastasis (HR 5.64, P < 0.001). In this group of RS + PN fat infiltration the 5-year cancer-specific survival was 31%.

CONCLUSION

Univariable and multivariable analyses showed that the combination of RS and PN fat infiltration is an independent unfavourable prognostic marker. We recommend that perirenal fat infiltration should be further differentiated into RS fat or PN infiltration in the TNM classification. This will better stratify patient prognosis and might allow those in need of adjuvant therapy to be identified.

Genetic clustering of clear cell renal cell carcinoma based on array-comparative genomic hybridization: its association with DNA methylation alteration and patient outcome

PURPOSE

The aim of this study was to clarify genetic and epigenetic alterations occurring during renal carcinogenesis.

EXPERIMENTAL DESIGN

Copy number alterations were examined by array-based comparative genomic hybridization analysis using an array harboring 4,361 bacterial artificial chromosome clones, and DNA methylation alterations on CpG islands of the p16, human MutL homologue 1, von Hippel-Lindau, and thrombospondin 1 genes and the methylated in tumor (MINT-1, MINT-2, MINT-12, MINT-25, and MINT-31) clones were examined in 51 clear cell renal cell carcinomas (RCC).

RESULTS

By unsupervised hierarchical clustering analysis based on copy number alterations, clear cell RCCs were clustered into the two subclasses, clusters A (n=34) and B (n=17). Copy number alterations were accumulated in cluster B. Loss of chromosome 3p and gain of 5q and 7 were frequent in both clusters A and B, whereas loss of 1p, 4, 9, 13q, and 14q was frequent only in cluster B. The average number of methylated CpG islands in cluster B was significantly higher than those in cluster A. Clear cell RCCs showing higher histologic grades, vascular involvement, renal vein tumor thrombi, and higher pathologic stages were accumulated in cluster B. The recurrence-free and overall survival rates of patients in cluster B were significantly lower than those of patients in cluster A. Multivariate analysis revealed that genetic clustering was a predictor of recurrence-free survival and was independent of histologic grade and pathologic stage.

CONCLUSIONS

This genetic clustering of clear cell RCC is significantly associated with regional DNA hypermethylation and may become a prognostic indicator for patients with RCC.