A Novel Grading System for Clear Cell Renal Cell Carcinoma Incorporating Tumor Necrosis

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.

CT-based radiomics model using stability selection for predicting the World Health Organization/International Society of Urological Pathology grade of clear cell renal cell carcinoma

OBJECTIVES

This study aimed to develop a model to predict World Health Organization/International Society of Urological Pathology (WHO/ISUP) low-grade or high-grade clear cell renal cell carcinoma (ccRCC) using 3D multiphase enhanced CT radiomics features (RFs).

METHODS

CT data of 138 low-grade and 60 high-grade ccRCC cases were included. RFs were extracted from four CT phases: non-contrast phase (NCP), corticomedullary phase, nephrographic phase, and excretory phase (EP). Models were developed using various combinations of RFs and subjected to cross-validation.

RESULTS

There were 107 RFs extracted from each phase of the CT images. The NCP-EP model had the best overall predictive value (AUC = 0.78), but did not significantly differ from that of the NCP model (AUC = 0.76). By considering the predictive ability of the model, the level of radiation exposure, and model simplicity, the overall best model was the Conventional image and clinical features (CICFs)-NCP model (AUC = 0.77; sensitivity 0.75, specificity 0.69, positive predictive value 0.85, negative predictive value 0.54, accuracy 0.73). The second-best model was the NCP model (AUC = 0.76).

CONCLUSIONS

Combining clinical features with unenhanced CT images of the kidneys seems to be optimal for prediction of WHO/ISUP grade of ccRCC. This noninvasive method may assist in guiding more accurate treatment decisions for ccRCC.

ADVANCES IN KNOWLEDGE

This study innovatively employed stability selection for RFs, enhancing model reliability. The CICFs-NCP model's simplicity and efficacy mark a significant advancement, offering a practical tool for clinical decision-making in ccRCC management.

Distinct spatial landscapes in clear-cell renal cell carcinoma as revealed by whole transcriptome analysis

Background

Clear-cell renal cell carcinoma (ccRCC) is the most common and aggressive form of renal cancer and a paradigm of inter- and intratumor heterogeneity. We carried out an exploratory digital spatial profiling of the tumor interior and periphery of two ccRCC tumor specimens and mapped spatially the molecular and cellular composition of their tumor microenvironment and ecosystem.

Materials and methods

Digital spatial profiling of the whole transcriptome of 19 regions of interest (ROIs) was carried out from two selected highly immunogenic stage pT3a/grade 3 (G3) and stage pT3a/grade 4 (G4) ccRCC. A total of 9-10 ROIs were selected from distinct areas from each tumor, including tumor interior and tumor periphery, and differences in gene expression were analyzed by RNA sequencing, pathway enrichment analysis, and cell deconvolution.

Results

The distinct areas from the two locally advanced tumors displayed unique gene expression spatial patterns defining distinct biological pathways. Dimensional reduction analysis showed that the G3 ccRCC, compared to the G4 ccRCC, correlated with more variability between regions from the tumor interior and tumor periphery. Cell deconvolution analysis illustrated higher abundance of immune cells, including macrophages, myeloid dendritic cells, and CD4 T cells, and lower abundance of regulatory T cells in the tumor periphery compared to the tumor interior.

Conclusions

Transcriptome spatial profiling revealed high inter- and intratumor heterogeneity in the analyzed tumors and provided information with potential clinical utility. This included the finding of less intratumor heterogeneity and more tumor-infiltrated T cells in the ccRCC tumor specimen with a higher grade.

Understanding Factors that Influence Prognosis and Response to Therapy in Clear Cell Renal Cell Carcinoma

In this review, we highlight and contextualize emerging morphologic prognostic and predictive factors in renal cell carcinoma. We focus on clear cell renal cell carcinoma (ccRCC), the most common histologic subtype. Our understanding of the molecular characterization of ccRCC has dramatically improved in the last decade. Herein, we highlight how these discoveries have laid the foundation for new approaches to prognosis and therapeutic decision-making for patients with ccRCC. We explore the clinical relevance of common mutations, established gene expression signatures, intratumoral heterogeneity, sarcomatoid/rhabdoid morphology and PD-L1 expression, and discuss their impact on predicting response to therapy.

World Health Organization (WHO) 2022 Classification Update: Radiologic and Pathologic Features of Papillary Renal Cell Carcinomas

RATIONALE AND OBJECTIVES

To describe imaging and pathology features of newly defined papillary renal cell carcinoma (pRCC) based on the WHO 2022 update.

MATERIALS AND METHODS

This retrospective study included 87 patients with 93 pathologically proven papillary renal cell carcinomas who underwent pre-treatment renal mass protocol CT or MRI. Baseline and post-treatment follow-up imaging was evaluated by two radiologists systematically based on established lexicon.

RESULTS

At pathology, 63 (68%) were grade 1-2, 29 (31%) were grade 3-4, and 1 (%) was unreported. At surgical pathology, 84 (90%) were localized (≤pT2b), 5 (5%) were pT3a, and none were ≥pT3b; 4 (4%) had unknown pT stage (core biopsies). 33 (35%) had necrosis and 39 (41%) had hemorrhage. None had sarcomatoid or rhabdoid differentiation. At imaging, 73 (83%) were solid and 16 (17%) were cystic. Of 16 cystic masses, four were Bosniak class IIF (three were heterogeneously T1 hyperintense) and 12 were class IV. All were well-circumscribed. 92 (99%) were hypovascular. Median follow-up for 74 patients was 30 months (IQR 12-56). One untreated patient had non-regional nodal metastasis at presentation, and one patient had metastasis to lymph nodes and bones after surgery, but the patient had unresected renal masses elsewhere without pathology. Otherwise, no recurrence or metastases were detected.

CONCLUSION

Most pRCCs present as a hypovascular, circumscribed, solid renal mass. A few pRCCs present as the newly defined Bosniak class IIF subtype. Our results can form the basis of a non-invasive, likelihood score to identify this relatively indolent pathology in the era of virtual biopsy and active surveillance.

Grading Clear Cell Renal Cell Carcinoma Grade Using Diffusion Relaxation Correlated MR Spectroscopic Imaging

BACKGROUND

Clear cell renal cell carcinoma (ccRCC) is the most common subtype of RCC, and accurate grading is crucial for prognosis and treatment selection. Biopsy is the reference standard for grading, but MRI methods can improve and complement the grading procedure.

PURPOSE

Assess the performance of diffusion relaxation correlation spectroscopic imaging (DR-CSI) in grading ccRCC.

STUDY TYPE

Prospective.

SUBJECTS

79 patients (age: 58.1 +/- 11.5 years; 55 male) with ccRCC confirmed by histopathology (grade 1, 7; grade 2, 45; grade 3, 18; grade 4, 9) following surgery.

FIELD STRENGTH/SEQUENCE

3.0 T MRI scanner. DR-CSI with a diffusion-weighted echo-planar imaging sequence and T2-mapping with a multi-echo spin echo sequence.

ASSESSMENT

DR-CSI results were analyzed for the solid tumor regions of interest using spectrum segmentation with five sub-region volume fraction metrics (VA , VB , VC , VD , and VE ). The regulations for spectrum segmentation were determined based on the D-T2 spectra of distinct macro-components. Tumor size, voxel-wise T2, and apparent diffusion coefficient (ADC) values were obtained. Histopathology assessed tumor grade (G1-G4) for each case.

STATISTICAL TESTS

One-way ANOVA or Kruskal-Wallis test, Spearman's correlation (coefficient, rho), multivariable logistic regression analysis, receiver operating characteristic curve analysis, and DeLong's test. Significance criteria: P < 0.05.

RESULTS

Significant differences were found in ADC, T2, DR-CSI VB , and VD among the ccRCC grades. Correlations were found for ccRCC grade to tumor size (rho = 0.419), age (rho = 0.253), VB (rho = 0.553) and VD (rho = -0.378). AUC of VB was slightly larger than ADC in distinguishing low-grade (G1-G2) from high-grade (G3-G4) ccRCC (0.801 vs. 0.762, P = 0.406) and G1 from G2 to G4 (0.796 vs. 0.647, P = 0.175), although not significant. Combining VB , VD , and VE had better diagnostic performance than combining ADC and T2 for differentiating G1 from G2-G4 (AUC: 0.814 vs 0.643).

DATA CONCLUSION

DR-CSI parameters are correlated with ccRCC grades, and may help to differentiate ccRCC grades.

EVIDENCE LEVEL

2 TECHNICAL EFFICACY STAGE: 2.

[68Ga]Ga‑LNC1007 PET/CT in the evaluation of renal cell carcinoma: comparison with 2-[18F]FDG/[68Ga]Ga-PSMA PET/CT

PURPOSE

To compare the potential efficiency of [68Ga]Ga-LNC1007 with 2-[18F]FDG/[68Ga]Ga-PSMA PET/CT for detecting renal cell carcinoma (RCC) and to explore parameters derived from [68Ga]Ga-LNC1007 PET/CT for discriminating pathological characteristics in RCC.

METHODS

Twenty-five RCC patients confirmed by pathology were enrolled in this prospective study. The maximum standardized uptake value (SUVmax), mean SUV (SUVmean), gross tumor volume (GTV) and total lesion-tracer (TL-tracer) of lesions were calculated from the corresponding PET/CT images. Pathological characteristics included World Health Organization/International Society of Urological Pathology (WHO/ISUP) grade and adverse pathological features (tumor necrosis or sarcomatoid or rhabdoid feature).

RESULTS

[68Ga]Ga-LNC1007 PET/CT showed a higher detection rate for primary lesions than 2-[18F]FDG and [68Ga]Ga-PSMA (LNC1007 vs. FDG: 13/17 vs. 4/17, P = 0.005; LNC1007 vs. PSMA: 9/11 vs. 6/11, P = 0.361). [68Ga]Ga-LNC1007 PET/CT showed higher SUVmax (6.6 vs. 3.7, P = 0.005), SUVmean (4.1 vs. 2.3, P = 0.001) and TBR (2.6 vs. 1.7, P = 0.011) compared with 2-[18F]FDG PET/CT, and it also showed higher TBR (2.9 vs. 0.5, P = 0.003), TBR-delay (2.8 vs. 0.3, P = 0.003), GTV (84.1 vs. 42.9, P = 0.003) and TL-tracer (442.7 vs. 235.8, P = 0.008) compared with [68Ga]Ga-PSMA PET/CT. SUVmax and TBR derived from [68Ga]Ga-LNC1007 PET/CT could effectively differentiate WHO/ISUP grade (3-4 vs. 1-2) and adverse pathological features (positive vs. negative) (SUVmax: AUC 0.81, P = 0.04; AUC 0.80, P = 0.033; TBR: AUC 0.84, P = 0.026; AUC 0.85, P = 0.014). The SUVmax was positively correlated with the FAP expression, integrin αvβ3 expression and the total expression of FAP and integrin αvβ3 (r = 0.577, P = 0.006, r = 0.701, P < 0.001, and r = 0.702, P < 0.001, respectively).

CONCLUSION

[68Ga]Ga-LNC1007 is a promising tracer for RCC imaging and can effectively identify aggressive pathological characteristics of RCC.

Immunolocalization of the AT-1R Ang II Receptor in Human Kidney Cancer

This study aimed to evaluate AT1-R expression in normal and cancerous human kidneys, how these expressions are modified, and AT1-R functionality. AT-1R mRNA expression, determined by real-time PCR, was detected in all samples. AT-1R mRNA increased in well-differentiated cancer (G1, p < 0.01) and decreased 2.9-fold in undifferentiated cancer (G4, p < 0.001) compared with normal kidney tissues. Immunocytochemistry analysis showed that the AT-1R was expressed in the normal tubular epithelium. The glomerulus was also immunoreactive, and as expected, the smooth muscle cells of the vessel walls also expressed the receptor. A total of 35 out of 42 tumors were AT-1R positive, with the cell tumors showing varying numbers of immunoreactive cells, which were stained in a diffuse cytoplasmic and membranous pattern. Computer-assisted counting of the stained tumor cells showed that the number of AT-1R-positive cells increased in the well-differentiated cancers. The functionality of AT-1R was assessed in primary cultures of kidney epithelial cells obtained from three G3 kidney cancer tissues and corresponding histologically proven non-malignant tissue adjacent to the tumor. Indeed, Ang II stimulated, in a dose-dependent manner, the 24 h proliferation of normal kidney cells and cancer cells in the primary culture and phosphorylated extracellular regulated kinases 1 and 2. In conclusion, Ang II may be involved in the growth or function of neoplastic kidney tissue.

Recent Advances in the Management of Clear Cell Renal Cell Carcinoma: Novel Biomarkers and Targeted Therapies

Renal cell carcinoma (RCC) belongs to a heterogenous cancer group arising from renal tubular epithelial cells. Among RCC subtypes, clear cell renal cell carcinoma (ccRCC) is the most common variant, characterized by high aggressiveness, invasiveness and metastatic potential, features that lead to poor prognosis and high mortality rate. In addition, diagnosis of kidney cancer is incidental in the majority of cases, and this results in a late diagnosis, when the stage of the disease is advanced and the tumor has already metastasized. Furthermore, ccRCC treatment is complicated by its strong resistance to chemo- and radiotherapy. Therefore, there is active ongoing research focused on identifying novel biomarkers which could be useful for assessing a better prognosis, as well as new molecules which could be used for targeted therapy. In this light, several novel targeted therapies have been shown to be effective in prolonging the overall survival of ccRCC patients. Thus, the aim of this review is to analyze the actual state-of-the-art on ccRCC diagnosis, prognosis and therapeutic options, while also reporting the recent advances in novel biomarker discoveries, which could be exploited for a better prognosis or for targeted therapy.

STING is a prognostic factor related to tumor necrosis, sarcomatoid dedifferentiation, and distant metastasis in clear cell renal cell carcinoma

STING is a molecule involved in immune reactions against double-stranded DNA fragments, released in infective and neoplastic diseases, whose role in the interactions between immune and neoplastic cells in clear cell renal cell carcinoma has not been studied yet. We investigated the immunohistochemical expression of STING in a series of 146 clear-cell renal cell carcinomas and correlated it with the main pathological prognostic factors. Furthermore, tumoral inflammatory infiltrate was evaluated and studied for the subpopulations of lymphocytes. Expression of STING was observed in 36% (53/146) of the samples, more frequently in high-grade (G3-G4) tumors (48%,43/90) and recurrent/metastatic ones (75%, 24/32) than in low grade (G1-G2) and indolent neoplasms (16%, 9/55). STING staining correlated with parameters of aggressive behavior, including coagulative granular necrosis (p = 0.001), stage (p < 0.001), and development of metastases (p < 0.001). Among prognostic parameters, STING immune expression reached an independent statistical significance (p = 0.029) in multivariable analysis, along with the stage and the presence of coagulative granular necrosis. About tumor immune-environment, no significant statistical association has been demonstrated between tumor-infiltrating lymphocytes and STING. Our results provide novel insights regarding the role of STING in aggressive clear cell renal cell carcinomas, suggesting its adoption as a prognostic marker and a potentially targetable molecule for specific immunotherapies.

Hot topics in renal cancer pathology: implications for clinical management

INTRODUCTION

The updated European Association of Urology (EAU) Guidelines issued a weak recommendation for adjuvant pembrolizumab for patients with high-risk operable clear cell Renal Cell Carcinoma (ccRCC). High risk of recurrence was defined, as per protocol-criteria, as T2 with nuclear grade 4 or sarcomatoid differentiation, T3 or higher, regional lymph node metastasis, or stage M1 with no evidence of disease. Considering the heterogeneous population included in the recommendation, it has been questioned if adjuvant pembrolizumab may lead to overtreatment of some patients as well as undertreatment of patients with worse prognosis.

AREAS COVERED

In this review, we discuss the issues related to the assessment of pathological features required to identify those patients harboring a high-risk tumor, highlighting the issue related to interobserver variability and discuss the currently available prognostic scoring systems in ccRCC.

EXPERT OPINION

PPathologist assessment of prognostic features suffers from interobserver variability which may depend on gross sampling and the pathologist's expertise. The presence of clear cell feature is not sufficient criteria by itself to define ccRCC since clear cell can be also found in other histotypes. Application of molecular biomarkers may be useful tools in the near future to help clinicians identify patients harboring tumors with worse prognosis.

An exploratory study of CT radiomics using differential network feature selection for WHO/ISUP grading and progression-free survival prediction of clear cell renal cell carcinoma

Objectives

To explore the feasibility of predicting the World Health Organization/International Society of Urological Pathology (WHO/ISUP) grade and progression-free survival (PFS) of clear cell renal cell cancer (ccRCC) using the radiomics features (RFs) based on the differential network feature selection (FS) method using the maximum-entropy probability model (MEPM).

Methods

175 ccRCC patients were divided into a training set (125) and a test set (50). The non-contrast phase (NCP), cortico-medullary phase, nephrographic phase, excretory phase phases, and all-phase WHO/ISUP grade prediction models were constructed based on a new differential network FS method using the MEPM. The diagnostic performance of the best phase model was compared with the other state-of-the-art machine learning models and the clinical models. The RFs of the best phase model were used for survival analysis and visualized using risk scores and nomograms. The performance of the above models was tested in both cross-validated and independent validation and checked by the Hosmer-Lemeshow test.

Results

The NCP RFs model was the best phase model, with an AUC of 0.89 in the test set, and performed superior to other machine learning models and the clinical models (all p &lt;0.05). Kaplan-Meier survival analysis, univariate and multivariate cox regression results, and risk score analyses showed the NCP RFs could predict PFS well (almost all p &lt; 0.05). The nomogram model incorporated the best two RFs and showed good discrimination, a C-index of 0.71 and 0.69 in the training and test set, and good calibration.

Conclusion

The NCP CT-based RFs selected by differential network FS could predict the WHO/ISUP grade and PFS of RCC.

The Histologic Diversity of Chromophobe Renal Cell Carcinoma With Emphasis on Challenges Encountered in Daily Practice

Chromophobe renal cell carcinoma (ChRCC) is the third most common renal cell carcinoma in adults. The aim of this review is to provide a comprehensive overview highlighting the broad morphologic spectrum of ChRCC, and offer a practical approach for handling cases in daily practice. For the purpose of this review, we classify ChRCC subtypes as (1) classic, (2) eosinophilic, (3) sarcomatoid, and (4) other rare patterns. The concept of eosinophilic ChRCC has significantly evolved, yet it still is one of the major diagnostic challenges pathologists face in routine practice due to its morphologic overlap with renal oncocytoma. Rare patterns of ChRCC have been described over the last few decades, showing a wide histologic spectrum including those with adenomatoid microcystic pigmented, multicystic, neuroendocrine, small cell, and papillary features. ChRCC represents a heterogenous group of neoplasms, demonstrating varied but unique morphologic and genetic profiles. Although the field of ChRCC knowledge is still evolving, rare patterns can present diagnostic challenges if they are not known to pathologists and/or clinicians. Proper and generous tumor sampling along with careful histologic examination allow for recognition of these rare morphologies. The role of routine molecular testing appears to be limited. From a clinical management standpoint, the rare patterns of ChRCC seem to have no definite clinical implications at present and likely can be managed similarly to usual ChRCC. Finally, we will discuss distinctive novel/emerging renal neoplasms previously considered under the spectrum of ChRCC, low-grade oncocytic renal tumor and eosinophilic vacuolated tumor, with regard to their current significance and implications for future classification strategies.

Development and validation of a vascularity-based architectural classification for clear cell renal cell carcinoma: correlation with conventional pathological prognostic factors, gene expression patterns, and clinical outcomes

The prognostic significance of an architectural grading system for clear cell renal cell carcinoma (ccRCC) has recently been demonstrated. The present study aimed to establish a vascularity-based architectural classification using the cohort of 436 patients with localized ccRCC who underwent extirpative surgery and correlated the findings with conventional pathologic factors, gene expression, and prognosis. First, we assessed architectural patterns in the highest-grade area on hematoxylin and eosin-stained slides, then separately evaluated our surrogate score for vascularity. We grouped nine architectural patterns into three categories based on the vascular network score. "Vascularity-based architectural classification" was defined: category 1: characterized by enrichment of the vascular network, including compact/small nested, macrocyst/microcystic, and tubular/acinar patterns; category 2: characterized by a widely spaced-out vascular network, including alveolar/large nested, thick trabecular/insular, papillary/pseudopapillary patterns; category 3: characterized by scattered vascularity without a vascular network, including solid sheets, rhabdoid and sarcomatoid patterns. Adverse pathological prognostic factors such as TNM stage, WHO/ISUP grade, and necrosis were significantly associated with category 3, followed by category 2 (all p < 0.001). We successfully validated the classification using The Cancer Genome Atlas (TCGA) cohort (n = 162), and RNA-sequencing data available from TCGA showed that the angiogenesis gene signature was significantly enriched in category 1 compared to categories 2 and 3, whereas the immune gene signature was significantly enriched in category 3 compared to categories 1 and 2. In univariate analysis, vascularity-based architectural classification showed the best accuracy in pathological prognostic factors for predicting recurrence-free survival (c-index = 0.786). The predictive accuracy of our model which integrated WHO/ISUP grade, necrosis, TNM stage, and vascularity-based architectural classification was greater than conventional risk models (c-index = 0.871 vs. 0.755-0.843). Our findings suggest that the vascularity-based architectural classification is prognostically useful and may help stratify patients appropriately for management based on their likelihood of post-surgical recurrence.

The clinical significance of epigenetic and RNAPII variabilities occurring in clear cell renal cell carcinoma as a potential prognostic marker

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30 ccRCC patients were used, to follow the epigenetic changes (γH2A.X, H3K4me3 and H3K9me3) and the alterations in the level of RNA polymerase II (RNAPII).

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The variabilities between the tumorous and non-tumorous parts of the tissue were measured by image analysis in which we monitored 30 cells from different positions of either the tumorous or the non-tumorous part of the tissue sections.

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These markers were classified to predict patient outcomes based on their individual cellular background. These results also support that detection of any alteration in the level of H3K4me3, H3K9me3, and γH2AX can account valuable information for presuming the progression of ccRCC and the clinical benefits to select the most efficient personalized therapy.

Patients diagnosed with clear cell renal cell carcinoma (ccRCC) have poor prognosis for recurrence and approximately 30–40% of them will later develop metastases. For this reason, the appropriate diagnosis and the more detailed molecular characterisation of the primary tumour, including its susceptibility to metastasis, are crucial to select the proper adjuvant therapy by which the most prosperous outcome can be achieved. Nowadays, clinicopathological variables are used for classification of the tumours. Apart from these, molecular biomarkers are also necessary to improve risk classification, which would be the most beneficial amongst modern adjuvant therapies. As a potential molecular biomarker, to follow the transcriptional kinetics in ccRCC patients (n=30), we analysed epigenetic changes (γH2A.X, H3K4me³, and H3K9me³) and the alterations in the level of RNA polymerase II (RNAPII) by immunohistochemical staining on dissected tissue sections. The variabilities between the tumorous and non-tumorous parts of the tissue were detected using quantitative image analysis by monitoring 30 cells from different positions of either the tumorous or the non-tumorous part of the tissue sections. Data obtained from the analyses were used to identify potential prognostic features and to associate them with the progression. These markers might have a value to predict patient outcomes based on their individual cellular background. These results also support that detection of any alteration in the level of H3K4me³, H3K9me³, and γH2A.X can account for valuable information for presuming the progression of ccRCC and the clinical benefits to select the most efficient personalised therapy.

Leveraging single cell sequencing to unravel intra-tumour heterogeneity and tumour evolution in human cancers

Intra-tumour heterogeneity and tumour evolution are well-documented phenomena in human cancers. While the advent of next-generation sequencing technologies has facilitated the large-scale capture of genomic data, the field of single cell genomics is nascent but rapidly advancing and generating many new insights into the complex molecular mechanisms of tumour biology. In this review, we provide an overview of current single cell DNA sequencing technologies, exploring how recent methodological advancements have enumerated new insights into intra-tumour heterogeneity and tumour evolution. Areas highlighted include the potential power of single cell genome sequencing studies to explore evolutionary dynamics contributing to tumourigenesis through to progression, metastasis and therapy resistance. We also explore the use of in-situ sequencing technologies to study intra-tumour heterogeneity in a spatial context, as well as examining the use of single cell genomics to perform lineage tracing in both normal and malignant tissues. Finally, we consider the use of multi-modal single cell sequencing technologies. Taken together, it is hoped that these many facets of single cell genome sequencing will improve our understanding of tumourigenesis, progression and lethality in cancer leading to the development of novel therapies. This article is protected by copyright. All rights reserved.

Prognostic Significance of Percentage Necrosis in Clear Cell Renal Cell Carcinoma

OBJECTIVES

The consensus conference of the International Society of Urological Pathology (ISUP), held in 2012, made recommendations regarding prognostic parameters of renal tumors. There was a strong consensus that tumor morphotype, pathologic tumor stage, and tumor grade are prognostic indicators of poor outcome. It was also agreed upon that prognostic significance of tumor necrosis is in evolution, and both microscopic and macroscopic tumor necrosis should be documented in percentages. The aim of our study was to explore the impact of tumor necrosis on metastasis-free survival in clear cell renal carcinomas (ccRCCs) in Pakistani patients.

METHODS

We retrieved 318 consecutive in-house cases of ccRCC resections from 2014 to 2020 through hospital archives. Histologic slide review was done for assessment of tumor necrosis, tumor stage, and World Health Organization/ISUP grade. The follow-up data to assess metastasis-free survival were available in hospital archives.

RESULTS

In multivariable analysis performed by logistic regression model, tumor necrosis was an independent poor prognostic indicator (P = .0001): group 1 (reference group), 0% necrosis; group 2, 1% to 10% necrosis (adjusted odds ratio [AOR], 8.71; 95% confidence interval [CI], 3.62-20.98); and group 3, more than 10% necrosis (AOR, 9.48; 95% CI, 3.99-22.725).

CONCLUSIONS

Tumor necrosis is an independent predictor of poor outcome in ccRCCs.

Microphysiological model of the renal cell carcinoma to inform anti-angiogenic therapy

Renal cell carcinomas are common genitourinary tumors characterized by high vascularization and strong reliance on glycolysis. Despite the many available therapies for renal cell carcinomas, first-line targeted therapies, such as cabozantinib, and durable reaponses are seen in only a small percentage of patients. Yet, little is known about the mechanisms that drive response (or lack thereof). This dearth of knowledge can be explained by the dynamic and complex microenvironment of renal carcinoma, which remains challenging to recapitulate in vitro. Here, we present a microphysiological model of renal cell carcinoma, including a tubular blood vessel model of induced pluripotent stem cell-derived endothelial cells and an adjacent 3D carcinoma model. Our model recapitulated hypoxia, glycolic metabolism, and sprouting angiogenesis. Using our model, we showed that cabozantinib altered cancer cell metabolism and decreased sprouting angiogenesis but did not restore barrier function. This microphysiological model could be helpful to elucidate, through multiple endpoints, the contributions of the relevant environmental components in eliciting a functional response or resistance to therapy in renal cell carcinoma.

Renal Oncocytoma: The Diagnostic Challenge to Unmask the Double of Renal Cancer

Renal oncocytoma represents the most common type of benign neoplasm that is an increasing concern for urologists, oncologists, and nephrologists due to its difficult differential diagnosis and frequent overtreatment. It displays a variable neoplastic parenchymal and stromal architecture, and the defining cellular element is a large polygonal, granular, eosinophilic, mitochondria-rich cell known as an oncocyte. The real challenge in the oncocytoma treatment algorithm is related to the misdiagnosis due to its resemblance, at an initial radiological assessment, to malignant renal cancers with a completely different prognosis and medical treatment. Unfortunately, percutaneous renal biopsy is not frequently performed due to the possible side effects related to the procedure. Therefore, the majority of oncocytoma are diagnosed after the surgical operation via partial or radical nephrectomy. For this reason, new reliable strategies to solve this issue are needed. In our review, we will discuss the clinical implications of renal oncocytoma in daily clinical practice with a particular focus on the medical diagnosis and treatment and on the potential of novel promising molecular biomarkers such as circulating microRNAs to distinguish between a benign and a malignant lesion.

Prognostic Factors for Localized Clear Cell Renal Cell Carcinoma and Their Application in Adjuvant Therapy

Simple Summary

Approximately one fifth of patients with newly diagnosed renal cell carcinoma (RCC) present with metastatic disease and over one third of the remaining patients with localized RCC will eventually have metastases spread to distant sites after complete resection of the primary tumor in the kidney. Usually, disease recurrence is observed within the first five years of follow-up, but late recurrences after five years are seen in up to 10% of patients. Despite novel biomarkers, simple histopathological factors, such as tumor size, tumor grade, and tumor extension into the blood vessels or beyond the kidney, are still valid features in predicting the risk of disease recurrence after surgery. The optimal set of prognostic factors remains unclear. The results from ongoing placebo-controlled adjuvant therapy trials may elucidate prognostic features that help to define high-risk patients for disease recurrence.

Abstract

Approximately 20% of patients with renal cell carcinoma (RCC) present with primarily metastatic disease and over 30% of patients with localized RCC will develop distant metastases later, after complete resection of the primary tumor. Accurate postoperative prognostic models are essential for designing personalized surveillance programs, as well as for designing adjuvant therapy and trials. Several clinical and histopathological prognostic factors have been identified and adopted into prognostic algorithms to assess the individual risk for disease recurrence after radical or partial nephrectomy. However, the prediction accuracy of current prognostic models has been studied in retrospective patient cohorts and the optimal set of prognostic features remains unclear. In addition to traditional histopathological prognostic factors, novel biomarkers, such as gene expression profiles and circulating tumor DNA, are extensively studied to supplement existing prognostic algorithms to improve their prediction accuracy. Here, we aim to give an overview of existing prognostic features and prediction models for localized postoperative clear cell RCC and discuss their role in the adjuvant therapy trials. The results of ongoing placebo-controlled adjuvant therapy trials may elucidate prognostic factors and biomarkers that help to define patients at high risk for disease recurrence.

Clear cell renal cell carcinoma with prominent microvascular hyperplasia: Morphologic, immunohistochemical and molecular-genetic analysis of 7 sporadic cases

Clear cell renal cell carcinoma (CCRCC) is well known for intratumor heterogeneity. An accurate mapping of the tumor is crucial for assessing prognosis, and perhaps this can be linked to potential success/failure of targeted therapies. We assembled a cohort of 7 CCRCCs with prominent vasculature and microvascular hyperplasia (ccRCCPV), resembling those seen in high grade gliomas. A control group of classic CCRCC with no variant morphologies was also included. Both groups were analyzed for clinicopathologic, morphologic, immunohistochemical, and molecular genetic features. No statistically significant differences in mRNA expression of studied genes between the two groups were found. Using NGS panel Trusight Oncology 500 (TSO500), only one clinically significant gene mutation, VHL c.263G > A, p. (Trp88Ter), was found. TMB (Tumor Mutation Burden) and MSI (MicroSatellite Instability) were low, and no copy number variations (CNVs) were detected in the study cohort. Prominent microvascular hyperplasia in CCRCC is a rare phenomenon. From molecular genetic point of view, these tumors do not appear to be different from classic CCRCC. Prognostically, they also demonstrated similar clinical behaviors.

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.

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.

High WHO/ISUP Grade and Unfavorable Architecture, Rather Than Typing of Papillary Renal Cell Carcinoma, May Be Associated With Worse Prognosis

Conflicting data have been published on the prognostic significance of histologic parameters in papillary renal cell carcinoma (PRCC). We conducted a comprehensive evaluation of clinical and histologic parameters in PRCC in nephrectomies and their impact on prognosis, with an emphasis on World Health Organization (WHO)/International Society of Urological Pathology (ISUP) grade, tumor architecture (solid, micropapillary, and hobnail), and PRCC type. A total of 185 PRCC cases were evaluated, 117 (63.2%) type 1, 45 (24.3%) type 2, and 11 (5.9%) mixed type 1 and type 2. Using WHO/ISUP grading criteria, PRCCs were graded as follows: 6 (3.2%) grade 1; 116 (62.7%) grade 2; 61 (33.0%) grade 3; and 2 (1.1%) grade 4. The solid architecture was present in 3 cases (1.6%) and comprised 10%, 10%, and 30% of the tumor area. Micropapillary architecture was present in 10 cases (5.4%), ranging from 5% to 30% of the tumor (mean=11%; median=10%). Hobnail architecture was seen in 9 cases (4.9%), with mean percentage of 23% (median=15%; range: 5% to 50%) involvement of tumor area. Parameters associated with worse disease-free survival (DFS) and overall survival (OS) in the univariate analysis included WHO/ISUP grade, pathologic stage, tumor size, and solid, micropapillary, or hobnail architecture (P<0.05). The pathologic stage and WHO/ISUP grade were significantly associated with both DFS and OS in stepwise multivariate Cox regression analysis (P<0.05). In addition, micropapillary architecture and type 1 histology were linked with an adverse impact on OS (P<0.05). We found no difference in DFS (P=0.8237) and OS (P=0.8222) for type 1 versus type 2 PRCC in our patient cohort. In addition, we performed a meta-analysis with data from studies with reported hazard ratios (HRs) on PRCC type in relation to DFS and OS. We identified 5 studies that reported DFS and found no significant effect for type 2 PRCC (P=0.30; HR=1.43; 95% confidence interval: 0.73-2.80). We identified 7 studies that reported OS and found no significant association between type 2 PRCC and worse OS (P=0.41; HR: 1.21; 95% confidence interval: 0.77-1.91). Our findings suggest that high WHO/ISUP grade and unfavorable architecture (solid, micropapillary, or hobnail), rather than typing of PRCC, are associated with worse outcomes.

Updates in Staging and Reporting of Genitourinary Malignancies

CONTEXT.—

The 8th edition of the American Joint Committee on Cancer (AJCC) staging manual changed the tumor, node, metastasis (TNM) classification systems of genitourinary malignancies in 2017. However, some of the changes appear not well appreciated or recognized by practicing pathologists.

OBJECTIVE.—

To review the major changes compared with the 7th edition in cancers of the prostate, penis, testis, bladder, urethra, renal pelvis/ureter, and kidney and discuss the challenges that pathologists may encounter.

DATA SOURCES.—

Peer-reviewed publications and the 8th and 7th editions of the AJCC Cancer Staging Manual.

CONCLUSIONS.—

This article summarizes the updated staging of genitourinary malignancies, specifically highlighting changes from the 7th edition that are relevant to the pathologic staging system. Pathologists should be aware of the updates made in hopes of providing clarification and the remaining diagnostic challenges associated with these changes.

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.

Comprehensive evaluation of 68Ga-PSMA-11 PET/CT parameters for discriminating pathological characteristics in primary clear-cell renal cell carcinoma

PURPOSE

To evaluate parameters derived from ⁶⁸Ga-PSMA-11 PET/CT images for discriminating pathological characteristics in primary clear-cell renal cell carcinoma (ccRCC).

METHODS

The study retrospectively examined data for 36 ccRCC patients with preoperative ⁶⁸Ga-PSMA-11 PET/CT scan and surgical specimens. Radiological parameters including maximal tumor diameter, mean CT value, and maximal standard uptake value (SUV_max) were derived from PET/CT images. Pathological characteristics included WHO/ISUP grade and adverse pathology (tumor necrosis or sarcomatoid or rhabdoid feature). Values of radiological parameters were compared within subgroups of pathological characteristics. Receiver operating characteristic (ROC) curve analysis was used for the effectiveness of radiological parameters in differentiating pathological characteristics, estimating area under the ROC curve (AUC) and 95% confidence intervals (CIs).

RESULTS

The WHO/ISUP grade distribution for 36 tumors was grade 1, 9 (25.0%); grade 2, 12 (33.3%); grade 3, 9 (25.0%); and grade 4, 6 (16.7%). Adverse pathology was positive for 15 (41.7%). Radiological tumor diameter and SUVmax significantly differed by WHO/ISUP grade, pT stage, and adverse pathology (all P < 0.05), with no difference by CT value. Tumor diameter demonstrated sensitivity 86% and specificity 88% for pT stage, with cutoff 6.70 and AUC 0.91 (95% CI, 0.79-1.00, P < 0.001). SUV_max could effectively differentiate WHO/ISUP grade (3-4 vs. 1-2) and adverse pathology (positive vs. negative), with AUC 0.89 (95% CI, 0.81-0.98, P < 0.001), cutoff 16.4, sensitivity 100%, and specificity 71% and AUC 0.92 (95% CI, 0.85-0.99, P < 0.001), cutoff 18.5, sensitivity 94%, and specificity 87%, respectively.

CONCLUSION

⁶⁸Ga-PSMA-11 PET/CT could effectively identify aggressive pathological features of ccRCC.

Granular necrosis: a distinctive form of cell death in malignant tumours

Foci of necrosis are frequently seen in malignant tumours and may be due to a variety of causes. Different types of necrosis are given various names based upon their morphological features and presumed pathogenesis, such as coagulative, liquefactive and fibrinoid necrosis. Here, we propose the term 'granular necrosis' (GN) for a specific form of tumour necrosis characterised by the presence of well-defined necrotic foci being sharply demarcated from adjacent viable tumour. A constant feature is loss of architecture resulting in an amorphous necrotic mass containing granular nuclear and cytoplasmic debris, without an associated neutrophilic infiltrate. There is usually extensive karyorrhexis, which in larger tumours is more prominent at the periphery. These foci are often microscopic but may range up to several millimetres or larger in size. This distinctive form of necrosis has been erroneously given a variety of names in the literature including coagulative necrosis and microscopic necrosis, which on the basis of the aforementioned gross and microscopic findings is inappropriate. It is apparent that this is a specific form of necrosis, hence the descriptive term 'granular necrosis' that differentiates this form of necrosis from other types. The presence of GN is recognised as occurring in a variety of tumour types, being commonly seen in renal cell carcinoma, where it has been shown to have independent prognostic significance. In some epithelial and stromal tumours of the uterus, the presence of GN also has prognostic significance and is a defining feature for the differentiation of uterine leiomyoma and leiomyosarcoma. The pathogenesis of GN is unresolved. It does not show the features of apoptosis and in recent studies has been shown to have some of the molecular changes associated with necroptosis.

A Computed Tomography-Based Radiomics Nomogram to Preoperatively Predict Tumor Necrosis in Patients With Clear Cell Renal Cell Carcinoma

Objective: To develop and validate a radiomics nomogram for preoperative prediction of tumor necrosis in patients with clear cell renal cell carcinoma (ccRCC). Methods: In total, 132 patients with pathologically confirmed ccRCC in one hospital were enrolled as a training cohort, while 123 ccRCC patients from second hospital served as the independent validation cohort. Radiomic features were extracted from corticomedullary and nephrographic phase contrast-enhanced computed tomography (CT) images. A radiomics signature based on optimal features selected by consistency analysis and the least absolute shrinkage and selection operator was developed. An image features model was constructed based on independent image features according to visual assessment. By integrating the radiomics signature and independent image features, a radiomics nomograph was constructed. The predictive performance of the above models was evaluated using receiver operating characteristic (ROC) curve analysis. Furthermore, the nomogram was assessed using calibration curve and decision curve analysis. Results: Thirty-seven features were used to establish a radiomics signature, which demonstrated better predictive performance than did the image features model constructed using tumor size and intratumoral vessels in the training and validation cohorts (p <0.05). The radiomics nomogram demonstrated satisfactory discrimination in the training (area under the ROC curve [AUC] 0.93 [95% CI 0.87-0.96]) and validation (AUC 0.87 [95% CI 0.79-0.93]) cohorts and good calibration (Hosmer-Lemeshow p>0.05). Decision curve analysis verified that the radiomics nomogram had the best clinical utility compared with the other models. Conclusion: The radiomics nomogram developed in the present study is a promising tool to predict tumor necrosis and facilitate preoperative clinical decision-making for patients with ccRCC.

Contrast-enhanced magnetic resonance (MR) T1 mapping with low-dose gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) is promising in identifying clear cell renal cell carcinoma histopathological grade and differentiating fat-poor angiomyolipoma

Background

This study aimed to identify clear cell renal cell carcinoma (ccRCC) histopathological grade and differentiate it from fat-poor angiomyolipoma (AML). This was achieved through contrast-enhanced magnetic resonance (MR) T1 mapping with intravenous low-dose gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA).

Methods

In total, 56 consecutive patients received MR scanning between January 2016 and December 2018 using the pre- and post- contrast-enhanced T1 mapping sequences with low-dose Gd-DTPA (0.036 mmol/kg). RCCs were pathologically proven in 40 patients after surgery and graded according to the International Society of Urological Pathology (ISUP) classification system. Ten AMLs were pathologically proven by surgery histopathology and six AMLs were diagnosed by magnetic resonance imaging (MRI). Patients were followed up for more than half a year. The mean T1 values of the renal lesion and ipsilateral normal renal parenchyma were measured before and after Gd-DTPA administration (T1p and T1e). The reduction of T1 value (T1d) and the ratio of its reduction (T1d %) were calculated and compared.

Results

In 40 ccRCCs, higher-grade [International Society of Urologic Pathology (ISUP) grade 3 and 4] and lower-grade (ISUP grade 1 and 2) ccRCCs were noted in 13 and 27 patients, respectively. The mean T1p was 1,514.8±139.4 ms and the mean T1d was 907.7±193.7 ms in the higher-grade ccRCCs, which were significantly higher than in the lower-grade ccRCCs (T1p =1,251.7±151.5 ms and T1d =648.5±218.2 ms, respectively; P<0.001). Fat-poor AMLs had higher T1p (1,677.3±104.8 ms) and T1e (865.6±251.5 ms) as compared to ccRCCs (P<0.001). Combined T1p + T1d showed the highest area under the curve (AUC) (0.912) in the differentiation of higher-grade ccRCCs from lower-grade ccRCCs (P=0.010). Combined T1p + T1e had the highest AUC (0.956) in the differentiation between ccRCCs and fat-poor AMLs (P=0.010). All T1 mapping metrics could discriminate between normal renal parenchyma and renal lesions (P<0.001). No significant difference was found in the T1p and T1e at different parts of the ipsilateral normal renal parenchyma. Interobserver agreement for quantitative longitudinal relaxation time in the T1 maps was excellent.

Conclusions

Contrast-enhanced T1 mapping with low-dose Gd-DTPA may provide a more reliable and accurate approach in identifying ccRCCs histopathological grade and differentiating ccRCCs from fat-poor AMLs.

Impact of sarcomatoid differentiation and rhabdoid differentiation on prognosis for renal cell carcinoma with vena caval tumour thrombus treated surgically

Background

Sarcomatoid differentiation in renal cell carcinoma (RCC) with vena caval tumour thrombus has been shown to be associated with aggressive behaviours and poor prognosis; however, evidence of the impact of rhabdoid differentiation on prognosis is lacking. This study evaluated the impact of sarcomatoid differentiation and rhabdoid differentiation on oncological outcomes for RCC with vena caval tumour thrombus treated surgically.

Methods

We retrospectively analysed patients treated surgically for RCC with vena caval tumour thrombus at our institute from Jan 2015 to Nov 2018. Prognostic variables were evaluated for associations with progression-free survival (PFS) and cancer-specific survival (CSS) by Kaplan–Meier survival analysis and log-rank test. Univariate and multivariate analyses were performed to determine independent prognostic variables.

Results

We identified 125 patients with RCC and vena caval tumour thrombus, including 17 (13.6%) with sarcomatoid differentiation alone, 8 (6.4%) with rhabdoid differentiation alone and 3 (2.4%) with both sarcomatoid and rhabdoid differentiation. Compared to pure RCC, patients with sarcomatoid differentiation but not rhabdoid differentiation have worse PFS (p = 0.018 and p = 0.095, respectively). The univariate and multivariate analyses both showed sarcomatoid differentiation as a significant predictor of PFS. Compared to pure RCC, patients with sarcomatoid differentiation (p = 0.002) and rhabdoid differentiation (p = 0.001) both had significantly worse CSS. The univariate analysis showed sarcomatoid differentiation, rhabdoid differentiation, metastasis and blood transfusion as significant predictors of CSS (All, p < 0.05). In the multivariate analysis, sarcomatoid differentiation (HR 3.90, p = 0.008), rhabdoid differentiation (HR 3.01, p = 0.042), metastasis (HR 3.87, p = 0.004) and blood transfusion (HR 1.34, p = 0.041) all remained independent predictors of CSS.

Conclusions

Sarcomatoid differentiation and rhabdoid differentiation are both independent predictors of poor prognosis in RCC with vena caval tumour thrombus treated surgically.

Clinicopathological Findings on 28 Cases with XP11.2 Renal Cell Carcinoma

Xp11.2 translocation carcinoma is a distinct subtype of renal cell carcinoma characterized by translocations involving the TFE3 gene. Our study included the morphological, immunohistochemical and clinicopathological examination of 28 Xp11.2 RCCs. The immunophenotype has been assessed by using CA9, CK7, CD10, AMACR, MelanA, HMB45, Cathepsin K and TFE3 immunostainings. The diagnosis was confirmed by TFE3 break-apart FISH in 25 cases. The ages of 13 male and 15 female patients, without underlying renal disease or having undergone chemotherapy ranged from 8 to 72. The mean size of the tumors was 78.5 mm. Forty-three percent of patients were diagnosed in the pT3/pT4 stage with distant metastasis in 6 cases. Histological appearance was branching-papillary composed of clear cells with voluminous cytoplasm in 13 and variable in 15 cases, including one tumor with anaplastic carcinoma and another with rhabdoid morphology. Three tumors were labeled with CA9, while CK7 was negative in all cases. Diffuse CD10 reaction was observed in 17 tumors and diffuse AMACR positivity was described in 14 tumors. The expression of melanocytic markers and Cathepsin K were seen only in 7 and 6 cases, respectively. TFE3 immunohistochemistry displayed a positive reaction in 26/28 samples. TFE3 rearrangement was detected in all the analyzed cases (25/25), including one with the loss of the entire labeled break-point region. The follow-up time ranged from 2 to 300 months, with 7 cancer-related deaths. In summary, Xp11.2 carcinoma is an uncommon form of renal cell carcinoma with a variable histomorphology and rather aggressive clinical course.

Ontological analyses reveal clinically-significant clear cell renal cell carcinoma subtypes with convergent evolutionary trajectories into an aggressive type

Background

Clear cell renal cell carcinoma (ccRCC) is a particularly challenging tumor type because of its extensive phenotypic variability as well as intra-tumoral heterogeneity (ITH). Clinically, this complexity has been reduced to a handful of pathological variables such as stage, grade and necrosis, but these variables fail to capture the breadth of the disease. How different phenotypes affect patient prognosis and influence therapeutic response is poorly understood. Extensive ITH illustrates remarkable plasticity, providing a framework to study tumor evolution. While multiregional genomic analyses have shown evolution from an ancient clone that acquires metastatic competency over time, these studies have been conducted agnostic to morphological cues and phenotypic plasticity.

Methods

We established a systematic ontology of ccRCC phenotypic variability by developing a multi-scale framework along three fundamental axes: tumor architecture, cytology and the microenvironment. We defined 33 parameters, which we comprehensively evaluated in 549 consecutive ccRCCs retrospectively. We systematically evaluated the impact of each parameter on patient outcomes, and assessed their contribution through multivariate analyses. We measured therapeutic impact in the context of anti-angiogenic therapies. We applied dimensionality reduction by t-distributed stochastic neighbor embedding (t-SNE) algorithms to tumor architectures for the study of tumor evolution superimposing tumor size and grade vectors. Evolutionary models were refined through empirical analyses of directed evolution of tumor intravascular extensions, and metastatic competency (as determined by tumor reconstitution in a heterologous host).

Findings

We discovered several novel ccRCC phenotypes, developed an integrated taxonomy, and identified features that improve current prognostic models. We identified a subset of ccRCCs refractory to anti-angiogenic therapies. We developed a model of tumor evolution, which revealed converging evolutionary trajectories into an aggressive type.

Interpretation

This work serves as a paradigm for deconvoluting tumor complexity and illustrates how morphological analyses can improve our understanding of ccRCC pleiotropy. We identified several subtypes associated with aggressive biology, and differential response to targeted therapies. By analyzing patterns of spatial and temporal co-occurrence, intravascular tumor extensions and metastatic competency, we were able to identify distinct trajectories of convergent phenotypic evolution.

Five decades of urologic pathology: the accelerating expansion of knowledge in renal cell neoplasia

Those who are knowledgeable in cosmology inform us that the expansion of the universe is such that the velocity at which a distant galaxy is receding from the observer is continually increasing with time. We humbly paraphrase that as "The bigger the universe gets, the faster it gets bigger." This is an interesting analogy for the expansion of knowledge in the field of renal tumor pathology over the past 30 to 50 years. It is clear that a multitude of dedicated investigators have devoted incalculable amounts of time and effort to the pursuit of knowledge about renal epithelial neoplasms. As a consequence of the contributions of numerous investigators over many decades, the most recent World Health Organization classification of renal neoplasms includes about 50 well defined and distinctive renal tumors, as well as various miscellaneous and metastatic tumors. In addition, a number of emerging or provisional new entities are under active investigation and may be included in future classifications. In this review, we will focus on a number of these tumors, tracing as accurately as we can the origins of their discovery, relating relevant additions to the overall knowledge base surrounding them, and in some instances addressing changes in nomenclature.

Use of quantitative T2 mapping for the assessment of renal cell carcinomas: first results

Background

Correct staging and grading of patients with clear cell renal cell carcinoma (cRCC) is of clinical relevance for the prediction of operability and for individualized patient management. As partial or radial resection with postoperative tumor grading currently remain the methods of choice for the classification of cRCC, non-invasive preoperative alternatives to differentiate lower grade from higher grade cRCC would be beneficial.

Methods

This institutional-review-board approved cross-sectional study included twenty-seven patients (8 women, mean age ± SD, 61.3 ± 14.2) with histopathologically confirmed cRCC, graded according to the International Society of Urological Pathology (ISUP). A native, balanced steady-state free precession T2 mapping sequence (TrueFISP) was performed at 1.5 T. Quantitative T2 values were measured with circular 2D ROIs in the solid tumor portion and also in the normal renal parenchyma (cortex and medulla). To estimate the optimal cut-off T2 value for identifying lower grade cRCC, a Receiver Operating Characteristic Curve (ROC) analysis was performed and sensitivity and specificity were calculated. Students’ t-tests were used to evaluate the differences in mean values for continuous variables, while intergroup differences were tested for significance with two-tailed Mann-Whitney-U tests.

Results

There were significant differences between the T2 values for lower grade (ISUP 1–2) and higher grade (ISUP 3–4) cRCC (p < 0.001), with higher T2 values for lower grade cRCC compared to higher grade cRCC. The sensitivity and specificity for the differentiation of lower grade from higher grade tumors were 83.3% (95% CI: 0.59–0.96) and 88.9% (95% CI: 0.52–1.00), respectively, using a threshold value of ≥110 ms. Intraobserver/interobserver agreement for T2 measurements was excellent/substantial.

Conclusions

Native T2 mapping based on a balanced steady-state free precession MR sequence might support an image-based distinction between lower and higher grade cRCC in a two-tier-system and could be a helpful addition to multiparametric imaging.

Electronic supplementary material

The online version of this article (10.1186/s40644-019-0222-8) 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.

Percentage grade 4 tumour predicts outcome for clear cell renal cell carcinoma

Heterogeneity of tumour grading is common in clear cell renal cell carcinoma (ccRCC). WHO/ISUP grading specifies that RCC should be graded based on the highest grade present in at least one high power field. This does not take into account the proportion of high grade tumour present in a cancer, which may itself influence outcome. Cases of ccRCC accessioned by Aquesta Uropathology, Brisbane, Australia, between 2008 and 2015, were reviewed and grading assigned according to WHO/ISUP criteria. For tumours classified as grade 3 (G3) and 4 (G4), the percentage of tumour showing G3 and G4 morphology was assessed for each case. Survival analysis, with time to the development of metastases as the clinical outcome, was performed for six grading subclasses (G3 <10%, G3 10-50%, G3 >50%, G4 <10%, G4 10-50%, G4 >50%). Of the 681 cases of ccRCC in the series, there were 153 cases classified as G3 (91 cases) and G4 (62 cases) for which follow-up was available. During the follow-up period of <1-89 months, 19 (20.9%) patients with G3 and 30 (48.3%) patients with G4 cancers developed metastatic disease. The three subgroups of <10%, 10-50% and >50% G3 tumour were not significant in predicting outcome (p=0.47). Separating G3 into two groups of ≤50% vs >50% was also not significantly associated with outcome (p=0.22). For the three subgroups of G4 ccRCC (<10%, 10-50% and >50% G4) a higher percentage of G4 correlated with time to the development of metastases (p=0.01). Even though G4 tumours as a whole had a significantly worse outcome than G3 tumours (p=0.0004), the difference between G4 <10% and G3 tumours was not significant (p=0.27). On multivariate analysis, that included pT staging category and tumour size, there was a significant difference in survival between G4<10% and G4>50% tumours (p=0.018). The results of the study suggest that for ccRCC, WHO/ISUP G4 category should incorporate the percentage of G4 tumour present.

Grading of renal cell carcinoma

Grading of renal cell carcinoma (RCC) has been recognised as a prognostic factor for almost 100 years. Numerous grading systems have been proposed, initially focusing upon a constellation of cytological features and more recently on nuclear morphology. It has been recommended that grading of RCC should be based upon nucleolar prominence/eosinophilia for grades 1-3, while grade 4 requires nuclear anaplasia (including tumour giant cells, sarcomatoid differentiation and/or rhabdoid morphology). The grading system was adopted formally by the International Society of Urological Pathology (ISUP) and subsequently by the World Health Organisation (WHO), being designated the WHO/ISUP grading classification in the fourth edition of the WHO classification tumours of the urinary system and male genital organs (2016). This grading system has been validated for both clear cell and papillary RCC. Validation studies for chromophobe RCC failed to demonstrate a correlation between grade and outcome for both the superseded Fuhrman grading system and the WHO/ISUP grading classification, and it has been recommended that these tumours not be graded. The WHO/ISUP system has been incorporated into the structured reports of the International Cancer Collaboration on Cancer Reporting for both clear cell and papillary RCC. It is also noted that other types of RCC may be graded, but it must be emphasised in the report that this is for descriptive and diagnostic purposes, and not outcome prediction. More recent studies have shown the incorporation of the presence of tumour necrosis into RCC grading to improve outcome prediction, and this has been validated in several studies.

Assessment of the extracellular volume fraction for the grading of clear cell renal cell carcinoma: first results and histopathological findings

OBJECTIVES

To assess the potential of T1 mapping-based extracellular volume fraction (ECV) for the identification of higher grade clear cell renal cell carcinoma (cRCC), based on histopathology as the reference standard.

METHODS

For this single-center, institutional review board-approved prospective study, 27 patients (17 men, median age 62 ± 12.4 years) with pathologic diagnosis of cRCC (nucleolar International Society of Urological Pathology (ISUP) grading) received abdominal MRI scans at 1.5 T using a modified Look-Locker inversion recovery (MOLLI) sequence between January 2017 and June 2018. Quantitative T1 values were measured at different time points (pre- and postcontrast agent administration) and quantification of the ECV was performed on MRI and histological sections (H&E staining).

RESULTS

Reduction in T1 value after contrast agent administration and MR-derived ECV were reliable predictors for differentiating higher from lower grade cRCC. Postcontrast T1_diff values (T1_diff = T1 difference between the native and nephrogenic phase) and MR-derived ECV were significantly higher for higher grade cRCC (ISUP grades 3-4) compared with lower grade cRCC (ISUP grades 1-2) (p < 0.001). A cutoff value of 700 ms could distinguish higher grade from lower grade tumors with 100% (95% CI 0.69-1.00) sensitivity and 82% (95% CI 0.57-0.96) specificity. There was a positive and strong correlation between MR-derived ECV and histological ECV (p < 0.01, r = 0.88). Interobserver agreement for quantitative longitudinal relaxation times in the T1 maps was excellent.

CONCLUSIONS

T1 mapping with ECV measurement could represent a novel in vivo biomarker for the classification of cRCC regarding their nucleolar grade, providing incremental diagnostic value as a quantitative MR marker.

KEY POINTS

• Reduction in MRI T1 relaxation times after contrast agent administration and MR-derived extracellular volume fraction are useful parameters for grading of clear cell renal cell carcinoma (cRCC). • T1 differences between the native and the nephrogenic phase are higher for higher grade cRCC compared with lower grade cRCC and MRI-derived extracellular volume fraction (ECV) and histological ECV show a strong correlation. • T1 mapping with ECV measurement may be helpful for the noninvasive assessment of cRCC pathology, being a safe and feasible method, and it has potential to optimize individualized treatment options, e.g., in the decision of active surveillance.

Predictive models composed by radiomic features extracted from multi-detector computed tomography images for predicting low- and high- grade clear cell renal cell carcinoma: A STARD-compliant article

To evaluate the values of conventional image features (CIFs) and radiomic features (RFs) extracted from multi-detector computed tomography (MDCT) images for predicting low- and high-grade clear cell renal cell carcinoma (ccRCC).Two hundred twenty-seven patients with ccRCC were retrospectively recruited. Five hundred seventy features including 14 CIFs and 556 RFs were extracted from MDCT images of each ccRCC. The CIFs were extracted manually and RFs by the free software-MaZda. Least absolute shrinkage and selection operator (Lasso) was applied to shrink the high-dimensional data set and select the features. Five predictive models for predicting low- and high-grade ccRCC were constructed by the selected CIFs and RFs. The 5 models were as follows: model of minimum mean squared error (minMSE) of CIFs (CIF-minMSE), minMSE of cortico-medullary phase (CMP) of kidney (CMP-minMSE), minMSE of parenchyma phase (PP) of kidney (PP-minMSE), the combined model of CIF-minMSE and CMP-minMSE (CIF-CMP-minMSE), and the combined model of CIF-minMSE and PP-minMSE (CIF-PP-minMSE). The Lasso regression equation of each model was constructed, and the predictive values were calculated. The receiver operating characteristic (ROC) curves of predictive values of the 5 models were drawn by SPSS19.0, and the areas under the curves (AUCs) were calculated.According to Lasso regression, 12, 19 and 10 features were respectively selected from the CIFs, RFs of CMP image and that of PP images to construct the 5 predictive models. The models ordered by their AUCs from large to small were CIF-CMP-minMSE (AUC: 0.986), CIF-PP-minMSE (AUC: 0.981), CIF-minMSE (AUC: 0.980), CMP-minMSE (AUC: 0.975), and PP-minMSE (AUC: 0.963). The maximum diameter of the largest axial section of ccRCC had a maximum weight in predicting the grade of ccRCC among all the features, and its cutoff value was 6.15 cm with a sensitivity of 0.901, a specificity of 0.963, and an AUC of 0.975.When combined with CIFs, RFs extracted from MDCT images contributed to the larger AUC of the predictive model, but were less valuable than CIFs when used alone. The CIF-CMP-minMSE was the optimal predictive model. The maximum diameter of the largest axial section of ccRCC had the largest weight in all features.

An Integrated Score and Nomogram Combining Clinical and Immunohistochemistry Factors to Predict High ISUP Grade Clear Cell Renal Cell Carcinoma

Objective: The International Society of Urological Pathology (ISUP) has proposed a grading system to classify renal cell carcinoma (RCC). However, classification using biopsy specimens remains problematic and, consequently, the accuracy of a biopsy-based diagnosis is relatively poor. This study aims to combine clinical and immunohistochemical (IHC) factors for the prediction of high ISUP grade clear cell RCC (ccRCC) in an attempt to complement and improve the accuracy of a biopsy-based diagnosis. Methods: A total of 362 ccRCC patients were enrolled in this study and used for the training set. We performed IHC analysis of 18 protein markers on standard tissue sections using an automated stainer. Multivariate logistic regression models were developed to evaluate independent predictors for high ISUP grade. We evaluated different prediction models using receiver operating characteristic (ROC) curves and area under the ROC curve (AUC) analysis. A nomogram for the derivation of an integrated score for predicting high ISUP grade ccRCC and a calibration curve were also plotted. Finally, an internal validation cohort was examined to evaluate the performance of our integrated scoring system and nomogram. Results: Multivariate logistic analyses revealed seven credible candidates for predicting high grade ISUP. These were age, tumor diameter, surgery, and CK7, Ki-67, PTEN, and MTOR protein expression. The ROC curves for the clinical, IHC and integrated models were compared in the training set, and the AUC for each was 0.731, 0.744, and 0.801, respectively. DeLong's test showed that the integrated model was significantly better at predicting high ISUP grade, when compared with the other models. Internal validation confirmed the good performance of the integrated score in predicting ISUP grade. Conclusion: We have developed a nomogram integrating clinical and immunohistochemical parameters to predict high ISUP grade for M0 ccRCC patients. This nomogram may offer potentially useful information during preoperative individualized patient risk assessment, and consequently may help urologists when planning personalized management regimens.

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.