Chromophobe renal cell carcinoma: the impact of tumor grade on outcome

Evaluation of American Urological Association Renal Cell Carcinoma Risk Groups for Chromophobe Renal Cell Carcinoma

OBJECTIVE

To develop and compare various models for risk stratification in chromophobe renal cell carcinoma (chrRCC). Models have been developed to predict progression-free (PFS) and cancer-specific survival (CSS) following surgery for localized renal cell carcinoma (RCC). Notably, chromophobe RCC (chrRCC) is not included in American Urological Association (AUA) risk stratification, as nuclear grading is not recommended.

METHODS

We queried our institutional registry to identify patients managed surgically for unilateral, sporadic, M0, chrRCC from 1970-2012. AUA risk groups were defined using reported criteria, excluding grade, and were compared to the Mayo system incorporating nodal involvement, perinephric/renal sinus fat invasion, and sarcomatoid differentiation. PFS and CSS were estimated using the Kaplan-Meier method. Predictive ability was summarized using c-indexes from Cox proportional hazard regression models.

RESULTS

A total of 257 patients were identified. Thirty-nine patients experienced disease progression at a median 30 months (IQR 5.0-84) and 25 died from chrRCC at a median 34 months (IQR 15-79) following surgery. PFS and CSS rates at 10 years after surgery were 84% and 90%, respectively. C-indexes for modified AUA and Mayo risk groups were similar at 0.76 and 0.75, respectively, for PFS, and 0.77 and 0.76, respectively for CSS.

CONCLUSION

The modified AUA and Mayo risk stratification systems have similarly robust c-indexes for PFS and CSS in chrRCC. These models can be used to counsel patients based on pathologic features, inform clinicians on appropriate follow-up pathways, and identify patients at risk of disease progression for enrollment in adjuvant systemic therapy trials.

Grading Challenges and Prognostic Insights in Chromophobe Renal Cell Carcinoma: A Retrospective Study of 72 Patients

Chromophobe RCC (ChRCC) carries the best prognosis among all RCC subtypes, yet it lacks a proper grading system. Various systems have been suggested in the past, causing much controversy, and Avulova et al. recently proposed a promising four-tier grading system that takes into consideration tumor necrosis. Dysregulation of the mammalian target of the rapamycin (mTOR) pathway plays a key role in ChRCC pathogenesis, highlighting its molecular complexity. The present retrospective study aimed to evaluate the prognostic factors associated with a more aggressive ChRCC phenotype. Materials and Methods: Seventy-two patients diagnosed with ChRCC between 2004 and 2017 were included in our study. Pathology reports and tissue blocks were reviewed, and immunohistochemistry (IHC) was performed in order to assess the expressions of CYLD (tumor-suppressor gene) and mTOR, among other markers. Univariate analysis was performed, and OS was assessed using the Kaplan-Meier method. Results: In our study, 74% of patients were male, with a mean age of 60 years, and the mean tumor size was 63 mm (±44). The majority (54%) were followed for more than 10 years at intervals ranging between 44 and 222 months. The risk of death was significantly higher for patients that were classified as Grade 4 in the Avulova system (HR: 5.83; 95% CI, 1.37-24.7; p: = 0.017). As far as the IHC is concerned, mTOR expression was associated with an HR of 8.57 (95% CI, 1.91-38.5; p = 0.005), and CYLD expression was associated with an HR of 17.3 (95% CI, 1.57-192; p = 0.02). Conclusions: In our study, the Avulova grading system seems to be positively correlated with OS in patients diagnosed with ChRCC. Furthermore, an elevated mTOR expression also shows a negative correlation with OS, whereas an elevated CYLD expression does not seem to exert a protective role. However, because only a small proportion (4.2%) of our patients died due to ChRCC, despite the long follow-up period, the results must be interpreted with caution. Further research is needed to validate our findings.

High-Grade, Nonsarcomatoid Chromophobe Renal Cell Carcinoma: A Series of 22 Cases With Novel Molecular Features on a Subset

Chromophobe renal cell carcinoma (ChRCC) is the third most common subtype of renal cell carcinoma and typically exhibits indolent behavior, though a rare subset can exhibit high-grade morphologic features and is associated with a poor prognosis. Although there are limited data on the molecular characteristics of metastatic and sarcomatoid ChRCC, the molecular features of high-grade, nonsarcomatoid ChRCC remain unexplored. Herein, we characterize 22 cases of ChRCC with high-grade, nonsarcomatoid components. High-grade ChRCC frequently demonstrated advanced stage at diagnosis (64% ≥pT3a or N1), with regions of extrarenal extension, nodal metastases, and vascular invasion consisting solely of high-grade ChRCC morphologically. We performed spatially guided panel-based DNA sequencing on 11 cases comparing high-grade and low-grade regions (n = 22 samples). We identified recurring somatic alterations emblematic of ChRCC, including deletions of chromosomes 1, 2, 6, 10, 13, 17, and 21 in 91% (10/11) of cases and recurring mutations in TP53 (81.8%, n = 9/11) and PTEN (36.4%, n = 4/11). Notably, although PTEN and TP53 alterations were found in both high-grade and low-grade regions, private mutations were identified in 3 cases, indicating convergent evolution. Finally, we identified recurring RB1 mutations in 27% (n = 3) of high-grade regions leading to selective protein loss by immunohistochemistry not observed in adjacent low-grade regions. This finding was confirmed in The Cancer Genome Atlas cohort where 2 of 66 cases contained RB1 mutations and demonstrated unequivocal high-grade, nonsarcomatoid morphology. We also detected multiple chromosomal gains confined to the high-grade regions, consistent with imbalanced chromosome duplication. These findings broaden our understanding of the molecular pathogenesis of ChRCC and suggest that subclonal RB1 mutations can drive the evolution to high-grade, nonsarcomatoid ChRCC.

Molecular underpinnings of dedifferentiation and aggressiveness in chromophobe renal cell carcinoma

Sarcomatoid dedifferentiation is common to multiple renal cell carcinoma (RCC) subtypes, including chromophobe RCC (ChRCC), and is associated with increased aggressiveness, resistance to targeted therapies, and heightened sensitivity to immunotherapy. To study ChRCC dedifferentiation, we performed multiregion integrated paired pathological and genomic analyses. Interestingly, ChRCC dedifferentiates not only into sarcomatoid but also into anaplastic and glandular subtypes, which are similarly associated with increased aggressiveness and metastases. Dedifferentiated ChRCC shows loss of epithelial markers, convergent gene expression, and whole genome duplication from a hypodiploid state characteristic of classic ChRCC. We identified an intermediate state with atypia and increased mitosis but preserved epithelial markers. Our data suggest that dedifferentiation is initiated by hemizygous mutation of TP53, which can be observed in differentiated areas, as well as mutation of PTEN. Notably, these mutations become homozygous with duplication of preexisting monosomes (i.e., chromosomes 17 and 10), which characterizes the transition to dedifferentiated ChRCC. Serving as potential biomarkers, dedifferentiated areas become accentuated by mTORC1 activation (phospho-S6) and p53 stabilization. Notably, dedifferentiated ChRCC share gene enrichment and pathway activation features with other sarcomatoid RCC, suggesting convergent evolutionary trajectories. This study expands our understanding of aggressive ChRCC, provides insight into molecular mechanisms of tumor progression, and informs pathologic classification and diagnostics.

Optimizing hepatocellular carcinoma disease staging systems by incorporating tumor micronecrosis: A multi-institutional retrospective study

Tumor micronecrosis is a pathological feature that reflects malignant biological behavior in hepatocellular carcinoma (HCC). However, whether micronecrosis can optimize HCC staging systems remains unilluminated. A total of 1632 HCC patients who underwent curative hepatectomy in four institutions from January 2014 to December 2021 were enrolled in this study. Independent prognostic factors were identified, and optimized staging models were established using a training cohort (n = 934). The performance of optimized staging models was validated using an external cohort consisting of cases from three other institutions (n = 232). In addition, patients from our prospectively collected database (n = 379) tested the application effectiveness of the models. Harrel's c-statistics and the corrected Akaike information criterion (AICc) were used to assess the performance of staging models. In most of Barcelona Clinic Liver Cancer (BCLC) and tumor (T) stages, HCC patients with tumor micronecrosis showed poorer prognosis than those without. Tumor micronecrosis, microvascular invasion, multiple tumors and tumor size >2 cm were independent prognostic-related factors. The BCLC and T staging models incorporating tumor micronecrosis showed better performance than the original systems (c-statistic, 0.712 and 0.711 vs. 0.664 and 0.679; AICc, 2314.8 and 2322.3 vs. 2338.2 and 2338.1; respectively). Furthermore, the external validation cohort confirmed that the optimized staging models had improved efficiency compared with the original ones. Moreover, the prospective cohort demonstrated the applicability of the optimized staging systems. Tumor micronecrosis plays a stage-ascending role in HCC patients. The BCLC and T staging systems incorporating tumor micronecrosis can improve the prognosis stratification efficiency of patients.

External validation of a four-tiered grading system for chromophobe renal cell carcinoma

This study aimed to validate the prognostic value of a four-tiered grading system recently proposed by Avulova et al. and to explore the prognostic ability of another four-tiered classification grading system in which there is a separate Grade 3 for tumor necrosis. Grading of chromophobe renal cell carcinoma (ChRCC) by the Fuhrman system is not feasible because of the inherent nuclear atypia in ChRCC. We collected relevant data of 263 patients with ChRCC who had undergone surgery in our hospital from 2008 to 2020. The Kaplan-Meier method was used to calculate the survival rate and Cox proportional hazard regression models to assess associations with cancer-specific survival and distant metastasis-free survival by hazard ratios (HRs) and 95% confidence intervals (CIs). Ten patients died from ChRCC, and 12 developed metastases. The 5 year CSS rates were 95.9%. Grades 2 (HR = 10.9; CI 1.11-106.4; P = 0.04), 3 (HR = 33.6, CI 3.32-339.1; P = 0.003), and 4 (HR = 417.4, CI 35.0-4976.2; P < 0.001) in a four-tiered grading system were significantly associated with CSS in a multivariate setting. However, the difference in CSS between Grades 2 and 3 was not significant (HR = 2.14, 95% CI 0.43-10.63; P = 0.35). The HRs of the associations between an exploratory grading system that includes a separate Grade 3 for tumor necrosis and CSS were as follows: Grade 2, 10.2 (CI 1.06-97.9, P = 0.045); Grade 3, 11.4 (CI 1.18-109.6, P = 0.04); and Grade 4, 267.9 (CI 27.6-2603.3, P < 0.001). Similarly, Grades 2 and 3 did not differ significantly. The four-tiered grading system studied is useful for predicting death from ChRCC and metastasis. However, Grade 3 did not more accurately predict risk of death and metastasis than did Grade 2. This was also true for the novel exploratory grading system that classifies tumors with necrosis into a separate Grade 3.

Empowering Renal Cancer Management with AI and Digital Pathology: Pathology, Diagnostics and Prognosis

Renal cell carcinoma is a significant health burden worldwide, necessitating accurate and efficient diagnostic methods to guide treatment decisions. Traditional pathology practices have limitations, including interobserver variability and time-consuming evaluations. In recent years, digital pathology tools emerged as a promising solution to enhance the diagnosis and management of renal cancer. This review aims to provide a comprehensive overview of the current state and potential of digital pathology in the context of renal cell carcinoma. Through advanced image analysis algorithms, artificial intelligence (AI) technologies facilitate quantification of cellular and molecular markers, leading to improved accuracy and reproducibility in renal cancer diagnosis. Digital pathology platforms empower remote collaboration between pathologists and help with the creation of comprehensive databases for further research and machine learning applications. The integration of digital pathology tools with other diagnostic modalities, such as radiology and genomics, enables a novel multimodal characterization of different types of renal cell carcinoma. With continuous advancements and refinement, AI technologies are expected to play an integral role in diagnostics and clinical decision-making, improving patient outcomes. In this article, we explored the digital pathology instruments available for clear cell, papillary and chromophobe renal cancers from pathologist and data analyst perspectives.

Evolution in the Pathologic Classification of Renal Neoplasia

The pathologic classification of renal tumors is a dynamic and complex process, which has evolved to a "histomolecular" driven system. Despite advances in molecular characterization, most renal tumors can be diagnosed by morphology with or without using a limited set of immunohistochemical stains. If access to molecular resources and specific immunohistochemical markers is limited, pathologists may face difficulties in following an optimal algorithm to classify renal tumors. In this article, we detail the historical evolution of renal tumor classification, including a synopsis of major changes introduced by the current fifth edition World Health Organization 2022 classification of renal epithelial tumors.

WHO 2022 landscape of papillary and chromophobe renal cell carcinoma

The 5th edition of the WHO Classification of Tumours of the Urinary and Male Genital Systems contains relevant revisions and introduces a group of molecularly defined renal tumour subtypes. Herein we present the World Health Organization (WHO) 2022 perspectives on papillary and chromophobe renal cell carcinoma with emphasis on their evolving classification, differential diagnosis, and emerging entities. The WHO 2022 classification eliminated the type 1/2 papillary renal cell carcinoma (pRCC) subcategorization, given the recognition of frequent mixed tumour phenotypes and the existence of entities with a different molecular background within the type 2 pRCC category. Additionally, emerging entities such as biphasic squamoid alveolar RCC, biphasic hyalinising psammomatous RCC, papillary renal neoplasm with reverse polarity, and Warthin-like pRCC are included as part of the pRCC spectrum, while additional morphological and molecular data are being gathered. In addition to oncocytomas and chromophobe renal cell carcinoma (chRCC), a category of 'other oncocytic tumours' with oncocytoma/chRCC-like features has been introduced, including emerging entities, most with TSC/mTOR pathway alterations (eosinophilic vacuolated tumour and so-called 'low-grade' oncocytic tumour), deserving additional research. Eosinophilic solid and cystic RCC was accepted as a new and independent tumour entity. Finally, a highly reproducible and clinically relevant universal grading system for chRCC is still missing and is another niche of ongoing investigation. This review discusses these developments and highlights emerging morphological and molecular data relevant for the classification of renal cell carcinoma.

Updates in Grading of Renal Cell Carcinomas Beyond Clear Cell Renal Cell Carcinoma and Papillary Renal Cell Carcinoma

The World Health Organization (WHO) recommends grading of clear cell renal cell carcinoma (RCC) and papillary RCC using the WHO/International Society of Urological Pathology (ISUP) grade, which is primarily based on nuclear features. As the spectrum of RCC continues to evolve, with more recently described subtypes in the past decade, literature evidence on grading these subtypes is limited or not available for some tumor types. Herein, we outline a pragmatic approach to the topic of grading RCC, dividing the contemporarily described RCC subtypes into 7 categories based on the potential clinical applicability of grading as a useful prognostic parameter: (1) RCC subtypes that are reasonably validated and recommended for WHO/ISUP grading; (2) RCC subtypes where WHO/ISUP is not applicable; (3) RCC subtypes where WHO/ISUP grading is potentially clinically useful; (4) inherently aggressive RCC subtypes where histologic classification itself confers an aggressive biologic potential; (5) renal epithelial tumors where WHO/ISUP grading provides potentially misleading prognostic implication; (6) renal epithelial neoplasms where low WHO/ISUP grade features are a prerequisite for accurate histologic classification; and (7) renal epithelial neoplasms with no or limited data on grading or incomplete understanding of the biologic potential. Our aim in outlining this approach is 2-fold: (a) identify the gaps in understanding and application of grading in RCC subtypes so that researchers in the field may perform additional studies on the basis of which the important pathologic function of assignment of grade may be recommended to be performed as a meaningful exercise across a wider spectrum of RCC; and (b) to provide guidance in the interim to surgical pathologists in terms of providing clinically useful grading information in RCC based on currently available clinicopathologic information.

MALDI Mass Spectrometry Imaging-Prognostic Pathways and Metabolites for Renal Cell Carcinomas

Simple Summary

Renal cell carcinoma (RCC) is the seventh most common cancer type and accounts for more than 80% of all renal tumors. Nevertheless, prognostic biomarkers for RCC are still missing. Therefore, we analyzed a large, multicenter cohort including the three most common RCC subtypes (clear cell RCC (ccRCC), papillary RCC (pRCC) and chromophobe RCC (chRCC)) by high mass resolution matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) for prognostic biomarker detection. This is a suitable method for biomarker detection for several tumor entities. We detected several pathways and metabolites with prognostic power for RCC in general and also for different RCC subtypes.

Abstract

High mass resolution matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) is a suitable method for biomarker detection for several tumor entities. Renal cell carcinoma (RCC) is the seventh most common cancer type and accounts for more than 80% of all renal tumors. Prognostic biomarkers for RCC are still missing. Therefore, we analyzed a large, multicenter cohort including the three most common RCC subtypes (clear cell RCC (ccRCC), papillary RCC (pRCC) and chromophobe RCC (chRCC)) by MALDI for prognostic biomarker detection. MALDI-Fourier-transform ion cyclotron resonance (FT-ICR)-MSI analysis was performed for renal carcinoma tissue sections from 782 patients. SPACiAL pipeline was integrated for automated co-registration of histological and molecular features. Kaplan–Meier analyses with overall survival as endpoint were executed to determine the metabolic features associated with clinical outcome. We detected several pathways and metabolites with prognostic power for RCC in general and also for different RCC subtypes.

Differential Immunohistochemical and Molecular Profiling of Conventional and Aggressive Components of Chromophobe Renal Cell Carcinoma: Pitfalls for Diagnosis

Chromophobe renal cell carcinoma (ChRCC) is a relatively rare subtype of RCC with a characteristic histologic appearance. Most ChRCC are slow growing, but sarcomatoid differentiation and metastases can occur, indicative of aggressive behavior and poor prognosis. Herein, we characterize ten ChRCC with aggressive components, defined as sarcomatoid change and/or metastasis. Immunohistochemistry and next-generation sequencing was performed on available formalin-fixed paraffin-embedded tissue, with differential profiling of conventional and aggressive components. All ten cases showed a conventional component of renal tumor morphologically consistent with ChRCC: three had sarcomatoid change, four had metastases, and three had both sarcomatoid change and metastases. In the primary conventional components, a typical ChRCC IHC pattern (CK7+, CD117+ and CAIX-) was observed in 8/10 cases; 2 cases had rare CK7 staining. In the aggressive components, CD117 and/or CK7 was lost in 7/10 cases; 3 cases showed loss of both. Two of 10 cases showed significant CAIX staining in the aggressive component. All 7 cases that had molecular profiling performed showed characteristic chromosomal losses reported for ChRCC, though two cases showed additional complex copy number alterations in the aggressive component only. Recurrent TP53 mutations (TP53m) were also seen; however surprisingly, the conventional and aggressive components had no shared TP53m: a TP53m was private to aggressive components in 2 cases; to the conventional component in 1 case; and in 4 cases, components demonstrated different TP53m. Of the 21 pathogenic alterations identified in 7 tumors, only a PTEN splicing alteration was shared between both components in one case. In conclusion, ChRCC can have IHC staining patterns and molecular profile that differ between conventional and aggressive components. Interpretation of stains on metastases or small biopsies to determine histologic subtype can be misleading. The lack of shared pathogenic mutations between the two components supports a model in which aggressive ChRCC can have convergent subclones with different TP53m.

[Oncocytic tumours of the kidney-new differential diagnoses]

BACKGROUND

Recent developments in differential diagnosis have led to new knowledge about oncocytic renal neoplasms.

OBJECTIVES

Overview of differential diagnosis of oncocytic tumours.

MATERIALS AND METHODS

We performed a literature search on oncocytic renal tumours and mapped known tumour types. Possible differential diagnoses are discussed.

RESULTS

Besides the tumour types already acknowledged by the 2016 WHO classification, there is new evidence regarding the group of hard-to-classify oncocytic neoplasms. Findings point to immunohistochemical and molecular characteristics that may lead to the establishment of new entities in the future. In addition, important differential diagnosis can now be identified, facilitating specific therapies for oncocytic renal tumours.

CONCLUSION

A correct diagnosis of oncocytic renal tumours not only improves prognostic assessment (and, if necessary, specific therapies) but is also clinically relevant regarding a possible association with hereditary tumour syndromes.

Chromophobe Renal Cell Carcinoma with Radiologic-Pathologic Correlation

Renal cell carcinoma (RCC) is a heterogeneous group of neoplasms derived from the renal tubular epithelial cells. Chromophobe RCC (chRCC) is the third most common subtype of RCC, accounting for 5% of cases. chRCC may be detected as an incidental finding or less commonly may manifest with clinical symptoms. The mainstay of therapy for chRCC is surgical resection. chRCC has a better prognosis compared with the more common clear cell RCC. At gross pathologic analysis, chRCC is a solid well-defined mass with lobulated borders. Histologic findings vary by subtype but include large pale polygonal cells with abundant transparent cytoplasm, crinkled "raisinoid" nuclei with perinuclear halos, and prominent cell membranes. Pathologic analysis reveals only moderate vascularity. The most common imaging pattern is a predominantly solid renal mass with circumscribed margins and enhancement less than that of the renal cortex. The authors discuss chRCC with emphasis on correlative pathologic findings and illustrate the multimodality imaging appearances of chRCC by using cases from the Radiologic Pathology Archives of the American Institute for Radiologic Pathology. ^©RSNA, 2021.

Metabolic imaging with hyperpolarized 13 C pyruvate magnetic resonance imaging in patients with renal tumors-Initial experience

BACKGROUND

Optimal treatment selection for localized renal tumors is challenging because of their variable biologic behavior and limitations in the preoperative assessment of tumor aggressiveness. The authors investigated the emerging hyperpolarized (HP) ¹³ C magnetic resonance imaging (MRI) technique to noninvasively assess tumor lactate production, which is strongly associated with tumor aggressiveness.

METHODS

Eleven patients with renal tumors underwent HP ¹³ C pyruvate MRI before surgical resection. Tumor ¹³ C pyruvate and ¹³ C lactate images were acquired dynamically. Five patients underwent 2 scans on the same day to assess the intrapatient reproducibility of HP ¹³ C pyruvate MRI. Tumor metabolic data were compared with histopathology findings.

RESULTS

Eight patients had tumors with a sufficient metabolite signal-to-noise ratio for analysis; an insufficient tumor signal-to-noise ratio was noted in 2 patients, likely caused by poor tumor perfusion and, in 1 patient, because of technical errors. Of the 8 patients, 3 had high-grade clear cell renal cell carcinoma (ccRCC), 3 had low-grade ccRCC, and 2 had chromophobe RCC. There was a trend toward a higher lactate-to-pyruvate ratio in high-grade ccRCCs compared with low-grade ccRCCs. Both chromophobe RCCs had relatively high lactate-to-pyruvate ratios. Good reproducibility was noted across the 5 patients who underwent 2 HP ¹³ C pyruvate MRI scans on the same day.

CONCLUSIONS

The current results demonstrate the feasibility of HP ¹³ C pyruvate MRI for investigating the metabolic phenotype of localized renal tumors. The initial data indicate good reproducibility of metabolite measurements. In addition, the metabolic data indicate a trend toward differentiating low-grade and high-grade ccRCCs, the most common subtype of renal cancer.

LAY SUMMARY

Renal tumors are frequently discovered incidentally because of the increased use of medical imaging, but it is challenging to identify which aggressive tumors should be treated. A new metabolic imaging technique was applied to noninvasively predict renal tumor aggressiveness. The imaging results were compared with tumor samples taken during surgery and showed a trend toward differentiating between low-grade and high-grade clear cell renal cell carcinomas, which are the most common type of renal cancers.

[Histological subtypes of renal cell carcinoma : Overview and new developments]

BACKGROUND

The classification of renal cell carcinoma (RCC) has changed remarkably in recent years.

OBJECTIVES

This is a short overview of the classification of RCC, focusing on new developments.

MATERIALS AND METHODS

A literature search was performed resulting in an overview of the classification of RCC. Emerging entities were discussed in detail.

RESULTS

Apart from the RCC subtypes in the WHO classification of 2016, several emerging entities came up over the last few years that are characterized by typical morphology, immunophenotype, and especially specific genetic alterations.

CONCLUSION

Precise classification of RCC is the key to better prognostic assessment with potential tumor-specific therapy and plays an important role in the recognition of possible association with hereditary tumor syndromes.

Application and comparison of Fuhrman nuclear grading system with the novel tumor grading system for chromophobe renal cell carcinoma and its correlation with disease-specific events

Introduction

The grading system of chromophobe renal cell carcinoma (ChRCC) is not well established. In this study, we aimed to compare the application of Fuhrman nuclear grade (FNG) with the novel chromophobe tumor grade (CTG). We also evaluated the correlation of these two grading systems with the clinical outcome.

Materials and Methods

Consecutive cases of ChRCC diagnosed on nephrectomy during 2005-2014 were identified. The clinical details of the patients were retrieved. Histopathology slides were reviewed and the nuclear grading was assigned using standard FNG and the CTG system. The CTG and FNG gradings were correlated with clinical outcome.

Results

A total of 80 cases were retrieved. Distribution of FNG was as follows: FNG-1, 1 (1.3%); FNG-2, 23 (28.3%); FNG-3, 44 (55.0%); and FNG-4, 12 (15%). CTG distribution was as follows: CTG-1, 48 (60.0%); CTG-2, 20 (25.0%); and CTG-3 12 (15.0%). Follow-up data was available in 46 cases; the median follow-up was 23.9 months (range 1-96.4 months). The median time to recurrence/metastasis was 17.2 months (range 3.2-31.2 months). Mean disease-free survival (DFS) was 68.5 months. Both CTG (P < 0.001) and FNG (P = 0.001) correlated with DFS; however, only CTG retained this significance when only the nonsarcomatous cases were analyzed. On receiver operating characteristics curve analysis, CTG had higher predictive accuracy for DFS for the entire group, while FNG lost the statistical significance when the nonsarcomatous cases were analyzed. CTG (P = 0.001) but not FNG (P = 0.106) correlated with the disease-specific adverse events in non-sarcomatous cases.

Conclusions

It is possible to apply CTG in ChRCC. It is a better predictor of DFS and disease-specific adverse events. CTG is more appropriate and applicable than the FNG in grading ChRCC.

Validation of the World Health Organization/International Society of Urological Pathology grading for Chinese patients with clear cell renal cell carcinoma

Background

This study aimed to compare the World Health Organization/International Society of Urological Pathology (WHO/ISUP) grading system and the Fuhrman grading system and to verify the WHO/ISUP grade as a prognostic parameter of clear cell renal cell carcinoma (ccRCC) in a Chinese population.

Methods

The study consisted of 753 ccRCC patients treated with curative surgery between 2010 and 2018 at Xiangya Hospital Central South University (Changsha, China). All pathologic data were retrospectively reviewed by two pathologists. Cancer-specific survival (CSS) and recurrence-free survival (RFS) were examined as clinical outcomes.

Results

According to the WHO/ISUP grading system (ISUP group), nephrectomy type, pT stage and WHO/ISUP grade were independent risk factors for CSS (P<0.0001, P=0.0127 and P<0.0001, respectively) and RFS (P<0.0001, P=0.0077, and P<0.0001, respectively). In the Fuhrman group, nephrectomy type, pT stage and Fuhrman grade were independent risk factors for CSS (P<0.0001, P=0.0004, and P<0.0001, respectively) and RFS (P<0.0001, P=0.0001, and P<0.0001, respectively). The C-index for CSS and RFS using the Fuhrman grading system was 0.6323 and 0.6342, respectively, and that using the WHO/ISUP grading system was 0.6983 and 0.7005, respectively, both higher than the former (P=0.0185, and P=0.0172, respectively). In addition, upgrading from Fuhrman grade 2 to ISUP grade 3 resulted in worse CSS and RFS for ccRCC patients (P=0.0033 and P =0.0003, respectively).

Conclusions

We first verified correlations between the postoperative prognosis and WHO/ISUP grade of ccRCC in a Chinese population and confirmed that the ability to predict clinical outcomes with the WHO/ISUP grading system was superior to that with the Fuhrman grading system.

Chromophobe renal cell carcinoma: current and controversial issues

It has been 35 years since Professor Thoenes and his colleagues discovered chromophobe renal cell carcinoma (RCC). Since then, our knowledge about this tumour entity has changed and novel tumour entities have been discovered. The aim of this review is to discuss recent molecular findings and open questions in diagnosing chromophobe-like/oncocytic neoplasms. The broader differential diagnosis of chromophobe-like and oncocytoma-like neoplasms includes SDH-deficient renal cell carcinoma, fumarate hydratase (FH) deficient RCC, epitheloid angiomyolipoma ('oncocytoma like'), MiT family translocation RCC and the emerging entity of eosinophilic solid and cystic renal cell carcinoma. After separation of these tumours from chromophobe RCC, it becomes evident that chromophobe RCC are low malignant tumours with a 5-6% risk of metastasis. Recent next generation sequencing (NGS) and DNA methylation profiling studies have confirmed Thoenes' theory of a distal tubule derived origin of chromophobe RCC and renal oncocytomas. Comprehensive genomic analyses of chromophobe RCC have demonstrated a low somatic mutation rate and identified TP53 and PTEN as the most frequently mutated genes, whereas 'unclassified' RCC with oncocytic or chromophobe-like features can show somatic inactivating mutations of TSC2 or activating mutations of MTOR as the primary molecular alterations. For the future, it would be desirable to create a category of 'oncocytic/chromophobe RCC, NOS' with the potential of further molecular studies for identification of TSC1/2 mutations in these rare tumours.

Grading Chromophobe Renal Cell Carcinoma: Evidence for a Four-tiered Classification Incorporating Coagulative Tumor Necrosis

BACKGROUND

Although grading systems have been proposed for chromophobe renal cell carcinoma (ChRCC), including a three-tiered system by Paner et al (Paner GP, Amin MB, Alvarado-Cabrero I, et al. A novel tumor grading scheme for chromophobe renal cell carcinoma: prognostic utility and comparison with Fuhrman nuclear grade. Am J Surg Pathol 2010;34:1233-40), none have gained clinical acceptance, and the World Health Organization (WHO) currently recommends against grading ChRCC.

OBJECTIVE

To validate a previously published grading scheme and propose a scheme that includes tumor necrosis.

DESIGN, SETTING, AND PARTICIPANTS

A total of 266 patients who underwent nephrectomy for nonmetastatic ChRCC between 1970 and 2012 were reviewed for ChRCC grade according to the Paner system and coagulative tumor necrosis.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Associations with cancer-specific survival (CSS) were evaluated using Cox proportional hazard regression models and summarized with hazard ratios (HRs).

RESULTS AND LIMITATIONS

Twenty-nine patients died from RCC; the median follow-up was 11.0 (interquartile range 7.9-15.9) yr. ChRCC grade according to the Paner system was significantly associated with CSS, including the difference in outcome between grade 1 and 2 tumors. Among patients with grade 2 tumors, the presence of tumor necrosis helped delineate patients with worse CSS. As such, the Paner system was expanded to four tiers separating grade 2 into those with and without tumor necrosis. HRs for associations of the proposed grade 2, 3, and 4 tumors with CSS were 4.63 (p=0.007), 17.8 (p<0.001), and 20.9 (p<0.001), respectively. The study is limited by the lack of multivariable analysis including additional pathologic features.

CONCLUSIONS

The expansion of a previously reported ChRCC grading system from three to four tiers by the inclusion of tumor necrosis helps further delineate patient outcome and can, therefore, enhance patient counseling following surgery. It also aligns the number of ChRCC grades with the WHO/International Society of Urologic Pathology four-tiered grading systems for clear cell and papillary RCC.

PATIENT SUMMARY

Chromophobe renal cell carcinoma is the third most common type of renal cancer, and unlike other renal cancers, there is no accepted prognostic grading system. In this study, we found that a grading system that included a pathologic feature of tumor necrosis could better define outcomes for patients with chromophobe renal cell carcinoma.

Updates in Histologic Grading of Urologic Neoplasms

CONTEXT.—

Tumor histology offers a composite view of the genetic, epigenetic, proteomic, and microenvironmental determinants of tumor biology. As a marker of tumor histology, histologic grading has persisted as a highly relevant factor in risk stratification and management of urologic neoplasms (ie, renal cell carcinoma, prostatic adenocarcinoma, and urothelial carcinoma). Ongoing research and consensus meetings have attempted to improve the accuracy, consistency, and biologic relevance of histologic grading, as well as provide guidance for many challenging scenarios.

OBJECTIVE.—

To review the most recent updates to the grading system of urologic neoplasms, including those in the 2016 4th edition of the World Health Organization (WHO) Bluebook, with emphasis on issues encountered in routine practice.

DATA SOURCES.—

Peer-reviewed publications and the 4th edition of the WHO Bluebook on the pathology and genetics of the urinary system and male genital organs.

CONCLUSIONS.—

This article summarizes the recently updated grading schemes for renal cell carcinoma, prostate adenocarcinomas, and bladder neoplasms of the genitourinary tract.

Eosinophilic Kidney Tumors: Old and New

Context.—

Eosinophilic cytoplasm is the most common finding of difficult-to-classify kidney tumors. Morphology, cytogenetics, and immunohistochemical stains are discriminatory. This review compares well-recognized tumors such as granular clear cell carcinoma, papillary variants, chromophobe renal cell carcinoma, and oncocytoma and introduces newly described entities of hybrid oncocytic tumors, carcinomas defined by translocations, and carcinomas with deficiencies in the tricarboxylic acid cycle. The focus is on immunostaining, clinical correlations, and differential diagnoses. Representative examples of some entities are presented with elaboration on their workup.

Objective.—

To provide a review of the differential diagnoses for renal neoplasms with eosinophilic cytoplasm and elaborate on methods that may assist with correct identification.

Data Sources.—

Review of current literature on kidney tumors with eosinophilic cytoplasm, as well as the authors' personal experience.

Conclusions.—

Eosinophilic cytoplasm is a feature shared by many kidney tumors. Understanding the morphologic differences and the role of ancillary studies is key when encountering such a tumor.

Compare Fuhrman Nuclear and Chromophobe Tumor Grade on Chromophobe RCC

Background

Chromophobe renal cell carcinoma (chRCC) has a favorable prognosis. Due to irregular nuclei and nuclear pleomorphism, chRCC has a high Fuhrman nuclear grade (FNG). The chromophobe tumor grade (CTG) is a novel three-tier grading system that has been reported to be a better prognosticator than the traditional FNG. We compared the two nuclear grading systems in terms of patients’ clinical outcomes.

Patients and Method

We performed this retrospective chart review of all patients with chRCC from 2000 to 2017. All pathologic features and CTG and FNG results were re-evaluated.

Result

Eighteen patients’ records were reviewed with a mean follow-up of 70.6 months. The nuclear grading distribution was as follows: FNG 2, 56%; FNG 3, 39%; FNG 4, 5%; CTG 1, 78%; CTG 2, 17%; and CTG 3, 6%. Only one patient died. This patient had adrenal invasion, lung metastasis, sarcomatoid change and tumor necrosis, and the tumor was graded as FNG 4 and CTG 3. Overall survival was associated with both FNG and CTG.

Conclusion

Chromophobe RCC was associated with a low rate of cancer-specific death and sarcomatoid differentiation. Both FNG and CTG were associated with overall survival.

Metastatic Chromophobe Renal Cell Carcinoma: Presence or Absence of Sarcomatoid Differentiation Determines Clinical Course and Treatment Outcomes

BACKGROUND

Sarcomatoid features (SF) in renal cell carcinoma (RCC) denote poor prognosis. Data for metastatic chromophobe RCC (ChRCC) with SF are limited. We studied clinical outcomes and genomic features in this setting.

PATIENTS AND METHODS

We performed a retrospective review of newly diagnosed metastatic ChRCC patients; end points included overall survival (OS), time to treatment failure (TTF), and time to metastatic recurrence (TTR) after nephrectomy for localized disease. A subset of patients underwent next-generation sequencing (NGS). Outcomes were compared using nonparametric tests.

RESULTS

One hundred nine patients with metastatic ChRCC were identified including 29 with SF. Median TTR after nephrectomy was shorter for patients with versus without SF (2.7 months [95% confidence interval (CI), 0.7-6.9] versus 48.8 months [95% CI, 30.8-80.7], log rank P < .001). Median TTF during first-line therapy was shorter for patients with versus without SF (1.8 months [95% CI, 0.9-2.7] vs. 8.0 months [95% CI, 5.1-13.0]; log rank P < .001). No responses were observed in 6 patients treated with nivolumab including 4 with SF. Median OS was inferior for patients with versus without SF (38 months vs.7.5 months; hazard ratio, 4.7 [95% CI, 2.7-8.2]; P < .001). NGS, performed in 22 patients, showed that 64% and 45% harbored tumor protein P53 and phosphatase and tensin homolog alterations, respectively. Microsatellite instability high status was identified in 3 patients.

CONCLUSION

Metastatic ChRCC patients with SF had worse outcomes compared with those without SF. Median TTR < 3 months for this subgroup supports close surveillance after nephrectomy for localized tumors. Lack of benefit with various systemic regimens warrants studying underlying biology and investigating novel agents.

Chromophobe renal cell carcinoma with sarcomatoid differentiation containing various heterologous components

Renal cell carcinoma (RCC) occasionally has sarcomatoid differentiation and rarely contains heterologous components. We report a case of chromophobe RCC with sarcomatoid differentiation that had various heterologous components including a unique lipomatous area. The patient was an 83-year-old woman with a palpable mass in the left lower abdomen. Grossly, the tumor was 14 cm in diameter and had yellowish-to-whitish color with focal necrosis and hemorrhage. Histologically, the tumor was composed of an eosinophilic subtype of chromophobe RCC with sarcomatoid differentiation including mainly chondrosarcoma, some osteosarcoma and a lipomatous area. The heterologous components of sarcomatoid RCC are usually osteosarcoma or chondrosarcoma, and sarcomatoid RCC with multiple heterologous components is extremely rare.

Localized chromophobe renal cell carcinoma: preoperative imaging judgment and laparoscopic simple enucleation for treatment

Objective:

To evaluate the preoperative imaging manifestation and therapeutic effect of laparoscopic simple enucleation (SE) for localized chromophobe renal cell carcinoma (chRCC).

Materials and Methods:

Clinical data of 36 patients who underwent laparoscopic SE of localized chRCC at our institute were retrospectively analyzed. All patients underwent preoperative renal protocol CT (unenhanced, arterial, venous, and delayed images). CT scan characteristics were evaluated. After intraoperative occlusion of the renal artery, the tumor was free bluntly along the pseudocapsule and enucleated totally. The patients were followed up regularly after the operation.

Results:

Mean tumor diameter was 3.9±1.0 cm, 80% of tumors were homogeneous and all the tumors had complete pseudocapsule. The attenuation values were slightly lower than normal renal cortex and degree of enhancement of the tumors were significantly lower than normal renal cortex. Mean operation time was 104.3±18.2 min. Mean warm ischemia time (WIT) was 21.3±3.5 min. Mean blood loss was 78.6±25.4 mL. No positive surgical margin was identified. Mean postoperative hospital stay was 5.3±1.5 d. Hematuria occurred in 3 patients and all disappeared within 3 days. After a mean follow-up of 32.1±20.6 months, no patient had local recurrence or metastatic progression.

Conclusion:

Localized chRCCs have a great propensity for homogeneity and complete pseudocapsule. The attenuation values were slightly lower than normal renal cortex and small degree of enhancement. Laparoscopic SE is a safe and effective treatment for localized chRCC. The oncological results were satisfactory.

Diagnostic Accuracy of Unenhanced CT Analysis to Differentiate Low-Grade From High-Grade Chromophobe Renal Cell Carcinoma

OBJECTIVE

The objective of our study was to evaluate tumor attenuation and texture on unenhanced CT for potential differentiation of low-grade from high-grade chromophobe renal cell carcinoma (RCC).

MATERIALS AND METHODS

A retrospective study of 37 consecutive patients with chromophobe RCC (high-grade, n = 13; low-grade, n = 24) who underwent preoperative unenhanced CT between 2011 and 2016 was performed. Two radiologists (readers 1 and 2) blinded to the histologic grade of the tumor and outcome of the patients subjectively evaluated tumor homogeneity (3-point scale: completely homogeneous, mildly heterogeneous, or mostly heterogeneous). A third radiologist, also blinded to tumor grade and patient outcome, measured attenuation and contoured tumors for quantitative texture analysis. Comparisons were performed between high-grade and low-grade tumors using the chi-square test for subjective variables and sex, independent t tests for patient age and tumor attenuation, and Mann-Whitney U tests for texture analysis. Logistic regression models and ROC curves were computed.

RESULTS

There were no differences in age or sex between the groups (p = 0.652 and 0.076). High-grade tumors were larger (mean ± SD, 62.6 ± 34.9 mm [range, 17.0-141.0 mm] vs 39.0 ± 17.9 mm [16.0-72.3 mm]; p = 0.009) and had higher attenuation (mean ± SD, 45.5 ± 8.2 HU [range, 29.0-55.0 HU] vs 35.3 ± 8.5 HU [14.0-51.0 HU]; p = 0.001) than low-grade tumors. CT size and attenuation achieved good accuracy to diagnose high-grade chromophobe RCC: The AUC ± standard error was 0.85 ± 0.08 (p < 0.0001) with a sensitivity of 69.0% and a specificity of 100%. Subjectively, high-grade tumors were more heterogeneous (mildly or markedly heterogeneous: 69.2% [9/13] for reader 1 and 76.9% [10/13] for reader 2; reader 1, p = 0.024; reader 2, p = 0.001) with moderate agreement (κ = 0.57). Combined texture features diagnosed high-grade tumors with a maximal AUC of 0.84 ± 0.06 (p < 0.0001).

CONCLUSION

Tumor attenuation and heterogeneity assessed on unenhanced CT are associated with high-grade chromophobe RCC and correlate well with the histopathologic chromophobe tumor grading system.

Variation in nuclear size and PD-L2 positivity correlate with aggressive chromophobe renal cell carcinoma

Chromophobe renal cell carcinoma (CRCC) is not amenable to International Society for Urologic Pathology-endorsed nucleolar grading. Novel grading approaches were proposed, but the rarity of adverse pathology hampers their discriminatory value. We investigate simple linear micrometer measurements and a proposed immunostain in CRCCs. 32 patients' CRCCs were studied: 12 adverse cases (stage pT3, recurrence, or metastasis), 15 controls (stage ≤pT2, no recurrence or metastasis after >3 years), and 8 metastases (3 were paired with primary adverse cases). The ratio of greatest dimensions of largest and smallest nuclei, in each of 5 "worst" high-power fields, excluding those with degenerative features, was designated variation in nuclear size (VNS). Percent multinucleate cells (PMC) were also counted. Mouse anti PD-L2 monoclonal antibody immunostaining was performed. Mean VNS measured in adverse primary and control primary tumors were 3.7 ± 0.5 and 2.4 ± 0.4 respectively (P < .001), and 3.4 ± 0.4 for metastases (P < .001). Optimal VNS cut-off was 2.5, with sensitivity and specificity 0.85 and 0.81, respectively. PMCs were 6.0 ± 3.0 for adverse group, 5.7 ± 2.7 for controls, and 4.1 ± 1.6 for metastases (P = NS). PD-L2 could not discriminate adverse versus good primary tumors (χ²1.6, P = .2), but was higher in metastases (χ² 6.9, P < .01), or metastases plus adverse primary tumors (χ² 4.8, P = .03), compared to good-pathology primary tumors. In conclusion, VNS is an easily obtained measurement that can predict adverse behavior of chromophobe RCC, and may impart value for needle biopsy reporting and the choice of active surveillance. PD-L2 was elevated in metastases but was less useful for primary tumors.

Adult Renal Cell Carcinoma: A Review of Established Entities from Morphology to Molecular Genetics

According to the current World Health Organization (WHO), renal cell carcinomas (RCCs) that primarily affect adults are classified into 8 major subtypes. Additional emerging entities in renal neoplasia have also been recently recognized and these are discussed in further detail by Mehra et al (Emerging Entities in Renal Neoplasia, Surgical Pathology Clinics, 2015, Volume 8, Issue 4). In most cases, the diagnosis of a RCC subtype can be based on morphologic criteria, but in some circumstances the use of ancillary studies can aid in the diagnosis. This review discusses the morphologic, genetic, and molecular findings in RCCs previously recognized by the WHO, and provides clues to distinction from each other and some of the newer subtypes of RCC. As prognosis and therapeutic options vary for the different subtypes of RCC, accurate pathologic distinction is critical for patient care.

Pre-treatment neutrophil-to-lymphocyte ratio predicts tumor pathology in newly diagnosed renal tumors

PURPOSE

The neutrophil-to-lymphocyte ratio (NLR) predicts adverse outcomes after surgical treatment for clear cell renal cell carcinoma (ccRCC). However, its ability to distinguish aggressive from indolent renal tumors remains unknown. We therefore evaluated the association between NLR and pathologic outcomes at nephrectomy.

METHODS

From 1995 to 2008, 2402 patients underwent radical or partial nephrectomy for localized renal tumors. Of these, 2039 had an NLR within 90 days prior to surgery. Comparisons of NLR by tumor size, histologic subtype, and nuclear grade were evaluated.

RESULTS

Benign renal masses had a significantly lower NLR than malignant tumors (median 2.92 vs. 3.12; p = 0.037) with the greatest difference noted among renal lesions >7 cm (median 2.79 vs. 3.87; p < 0.001). There was a significant difference in NLR among RCC subtypes (p = 0.002), with cystic ccRCC demonstrating the lowest (median 2.48) and collecting duct RCC the highest NLR (median 5.99). Moreover, there was a significant increase in NLR with larger tumor size and greater nuclear grade (p < 0.001). Specifically, in patients with ccRCC, an incremental increase in tumor size (≤4 cm = 2.80, >4 but ≤7 cm = 3.09 and >7 cm = 3.95) and nuclear grade (G1 = 2.68, G2 = 2.87, G3 = 3.48, and G4 = 5.18) was associated with greater NLR (p < 0.001).

CONCLUSIONS

An elevated NLR is associated with RCC pathology, higher-grade tumors, and more aggressive histologic subtypes at the time of nephrectomy. Therefore, NLR appears to be a preoperative marker of biologically aggressive RCC and may be useful in predicting malignancy and guiding management among patients with suspicious renal tumors.

Gleason and Fuhrman no longer make the grade

Grading is an important prognostic parameter for prostate adenocarcinoma and renal cell carcinoma (RCC); however, the most frequently used classifications fail to account for advances in our understanding of the diagnostic features, classification and/or behaviour of these tumours. In 2005 and 2014, the International Society of Urological Pathology (ISUP) proposed changes to Gleason scoring with the adoption of the ISUP grading for prostate cancer in 2014 (grade 1, score 3 + 3; grade 2, score 3 + 4; grade 3, score 4 + 3; grade 4, score 8; grade 5, score 9-10). Internationally the Fuhrman grading system is widely employed despite criticisms related to its application, validity, and reproducibility. In 2012, the ISUP established a grading system for RCC (grade 1, the nucleolus is not seen or is inconspicuous and basophilic at ×400 magnification; grade 2, nucleoli are eosinophilic and clearly visible at ×400 magnification; grade 3, nucleoli are clearly visible at ×100 magnification; grade 4, tumours show extreme pleomorphism or rhabdoid and/or sarcomatoid morphology). This grading has been validated for clear cell RCC and papillary RCC. It was further recommended that chromophobe RCC not be graded. For other morphotypes of RCC, ISUP grading has not been validated as a prognostic parameter, but can be used for descriptive purposes.

The 2016 WHO Classification of Tumours of the Urinary System and Male Genital Organs-Part A: Renal, Penile, and Testicular Tumours

The fourth edition of the World Health Organization (WHO) classification of urogenital tumours (WHO "blue book"), published in 2016, contains significant revisions. These revisions were performed after consideration by a large international group of pathologists with special expertise in this area. A subgroup of these persons met at the WHO Consensus Conference in Zurich, Switzerland, in 2015 to finalize the revisions. This review summarizes the most significant differences between the newly published classification and the prior version for renal, penile, and testicular tumours. Newly recognized epithelial renal tumours are hereditary leiomyomatosis and renal cell carcinoma (RCC) syndrome-associated RCC, succinate dehydrogenase-deficient RCC, tubulocystic RCC, acquired cystic disease-associated RCC, and clear cell papillary RCC. The WHO/International Society of Urological Pathology renal tumour grading system was recommended, and the definition of renal papillary adenoma was modified. The new WHO classification of penile squamous cell carcinomas is based on the presence of human papillomavirus and defines histologic subtypes accordingly. Germ cell neoplasia in situ (GCNIS) of the testis is the WHO-recommended term for precursor lesions of invasive germ cell tumours, and testicular germ cell tumours are now separated into two fundamentally different groups: those derived from GCNIS and those unrelated to GCNIS. Spermatocytic seminoma has been designated as a spermatocytic tumour and placed within the group of non-GCNIS-related tumours in the 2016 WHO classification.

PATIENT SUMMARY

The 2016 World Health Organization (WHO) classification contains new renal tumour entities. The classification of penile squamous cell carcinomas is based on the presence of human papillomavirus. Germ cell neoplasia in situ of the testis is the WHO-recommended term for precursor lesions of invasive germ cell tumours.

Distal nephron neoplasms

Tumours of the distal nephron are uncommon but can create diagnostic difficulties. They may be divided into three groups-tumours of intercalated cell phenotype, those of principal cell phenotype and others with an unconfirmed distal nephron origin. Oncocytomas, chromophobe carcinoma and hybrid oncocytoma chromophobe carcinoma, all show features of intercalated cells and the distinction amongst these is one of the most common areas of diagnostic dilemma. Collecting duct carcinoma and renal medullary carcinoma are the most aggressive forms of renal cancer but recent evidence suggests they may respond to targeted therapy so their recognition becomes crucial to the management of these patients. There remains debate over the precise phenotype of both tubulocystic carcinoma and mucinous tubular and spindle cell carcinoma.

Tumor grade of clear cell renal cell carcinoma assessed by contrast-enhanced computed tomography

The purpose of this study was to clarify the association between CT findings and Fuhrman grade of clear cell renal cell carcinoma (ccRCC). The study group consisted of 214 surgically proven ccRCC in 214 patients. Contrast-enhanced CT studies were retrospectively assessed for tumor size, cystic versus solid, calcification, heterogeneity of lesions, percentage of non-enhancing (necrotic) areas, and growth pattern. CT findings and Fuhrman grade were compared. Nineteen of 22 (86.4%) cystic ccRCC were low grade (Fuhrman grades 1-2). There was no significant correlation between tumor size and grade in cystic ccRCC (P = 0.43). In predominantly solid ccRCC, there was significant correlation between tumor size and grade (P < 0.0001). Thirty-eight of 43 (88.4%) infiltrative ccRCC were high grade (Fuhrman grades 3-4). Logistic regression showed tumor size and infiltrative growth were significantly associated with grades 3-4 (P = 0.00083 and P = 0.0059). Cystic ccRCC tends to be low grade. Infiltrative growth and larger tumor size may increase the likelihood of high grade ccRCC.

Diagnostic approach to eosinophilic renal neoplasms

CONTEXT

Eosinophilic renal neoplasms include a spectrum of solid and papillary tumors ranging from indolent benign oncocytoma to highly aggressive malignancies. Recognition of the correct nature of the tumor, especially in biopsy specimens, is paramount for patient management.

OBJECTIVE

To review the diagnostic approach to eosinophilic renal neoplasms with light microscopy and ancillary techniques.

DATA SOURCES

Review of the published literature and personal experience.

CONCLUSIONS

The following tumors are in the differential diagnosis of oncocytic renal cell neoplasm: oncocytoma, chromophobe renal cell carcinoma (RCC), hybrid tumor, tubulocystic carcinoma, papillary RCC, clear cell RCC with predominant eosinophilic cell morphology, follicular thyroid-like RCC, hereditary leiomyomatosis-associated RCC, acquired cystic disease-associated RCC, rhabdoid RCC, microphthalmia transcription factor translocation RCC, epithelioid angiomyolipoma, and unclassified RCC. In low-grade nonpapillary eosinophilic neoplasms, distinction between oncocytoma and low-grade RCC mostly rests on histomorphology; however, cytokeratin 7 immunostain may be helpful. In high-grade nonpapillary lesions, there is more of a role for ancillary techniques, including immunohistochemistry for cytokeratin 7, CA9, CD10, racemase, HMB45, and Melan-A. In papillary eosinophilic neoplasms, it is important to distinguish sporadic type 2 papillary RCC from microphthalmia transcription factor translocation and hereditary leiomyomatosis-associated RCC. Histologic and cytologic features along with immunohistochemistry and fluorescence in situ hybridization tests for TFE3 (Xp11.2) and TFEB [t(6;11)] are reliable confirmatory tests. Eosinophilic epithelial neoplasms with architecture, cytology, and/or immunoprofile not qualifying for either of the established types of RCC should be classified as unclassified eosinophilic RCC and arbitrarily assigned a grade (low or high).

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.

Chromophobe renal cell carcinoma: multiphase MDCT enhancement patterns and morphologic features

OBJECTIVE

The purpose of this investigation is to retrospectively describe morphologic features, enhancement characteristics, and clinical outcomes in a series of pathologically proven chromophobe renal cell carcinomas (RCCs).

MATERIALS AND METHODS

Thirty-five patients who were imaged at a single institution between 2005 and 2012 with pathologically proven chromophobe RCC were identified, all of whom underwent preoperative renal protocol CT (unenhanced, arterial, venous, and delayed images). The morphologic characteristics of each tumor (e.g., necrosis, tumor composition, and calcification), as well as attenuation values (in Hounsfield units) of the tumor, aorta, inferior vena cava, and kidney were evaluated by a board-certified radiologist. In addition, information regarding patient demographics and survival was obtained by a separate radiologist from the electronic medical record.

RESULTS

Sixty percent of the patients were men, with a mean age of 60.2 years. Forty-six percent of cases were incidentally identified, without patient symptoms. None of the patients had evidence of distant metastatic disease, either on initial staging CT or over the course of follow-up (mean, 2.0 years). Mean maximal tumor diameter was 5.24 cm. Forty-six percent of tumors were homogeneous, 85% of lesions were either completely solid or mostly solid, 14% showed calcifications, and 34% showed a central scar or necrosis. Mean maximum attenuation values were 87.9 HU (arterial phase), 83.9 HU (venous phase), and 60.6 HU (delayed phase), with an average delayed washout of 31%. Tumor-to-cortex ratios for the three enhanced phases were 0.59, 0.48, and 0.50, respectively.

CONCLUSION

Chromophobe RCCs were found to have a wider variability of CT features than previously reported, although they do have a greater propensity for homogeneity and the presence of a central scar or necrosis. Their enhancement characteristics fall in between those of clear cell and papillary RCC, although there is considerable overlap.

Chromophobe renal cell carcinoma--chromosomal aberration variability and its relation to Paner grading system: an array CGH and FISH analysis of 37 cases

Genetically, chromophobe renal cell carcinoma (ChRCC) is characterized by multiple chromosomal changes, especially losses. The most common losses include chromosomes 1, 2, 6, 10, 13, 17, and 21. The Fuhrman grading system lacks prognostic relevance for ChRCC, and recently, a new grading system for ChRCC was proposed by Paner. The objective of this study was to map the spectrum of chromosomal aberrations (extent and location) in a large cohort of ChRCCs and relate these findings to the Paner grading system (PGS). A large cohort of ChRCC was reviewed and graded according to the PGS. All the cases were reevaluated and separated into groups according to their PGS. The final study set was 37 patients. ChRCCs were divided into PG 1-3, sarcomatoid, and aggressive groups. "Aggressive ChRCCs" were designated cases with known metastatic activity, local recurrence, aggressive growth to the adjacent organs, or invasive growth into the renal sinus (with/without angioinvasion). Sarcomatoid tumors were divided into their epithelial and sarcomatoid component (further molecular genetic analyses were performed separately). Array comparative genome hybridization and/or fluorescence in situ hybridization analysis was applied to 42 samples from the 37 cases. Multiple losses, as well as gains, were detected in different chromosomes. Regardless of the PGS groups, the most frequently detected losses involved chromosomes 1 (27/37), 2 (26/37), 6 (23/37), 10 (26/37), 13 (19/37), and 17 (24/37). Loss of chromosome 21 was found in 12/37 cases. The most frequently detected gains were found on chromosomes 4 (22/37), 7 (24/37), 15 (20/37), 19 (22/37), and 20 (21/37). Cluster analysis showed that there is no relation between PGS and particular pattern of chromosomal changes (losses or gains) in ChRCCs. Conclusions are as follows: (1) ChRCCs showed a significantly broader spectrum of chromosomal aberrations than previously recognized. While previously published chromosomal losses were found in our cohort, gains of multiple chromosomes were also identified in a high percentage. The most frequently detected gains involved chromosomes 4, 7, 15, 19, and 20. (2) There is no relation between chromosomal numerical changes and Paner grading system.