The Fuhrman grading system has no prognostic value in patients with nonsarcomatoid chromophobe renal cell carcinoma

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.

Renal Cell Tumors: Molecular Findings Reshaping Clinico-pathological Practice

Over the past 20 years, the number of subtypes of renal epithelial cell neoplasia has grown. This growth has resulted from detailed histological and immunohistochemical characterization of these tumors and their correlation with clinical outcomes. Distinctive molecular phenotypes have validated the unique nature of many of these tumors. This growth of unique renal neoplasms has continued after the 2016 World Health Organization (WHO) Classification of Tumours. A consequence is that both the pathologists who diagnose the tumors and the clinicians who care for these patients are confronted with a bewildering array of renal cell carcinoma variants. Many of these variants have important clinical features, i.e. familial or syndromic associations, genomics alterations that can be targeted with systemic therapy, and benignancy of tumors previously classified as carcinomas. Our goal in the review is to provide a practical guide to help recognize these variants, based on small and distinct sets of histological features and limited numbers of immunohistochemical stains, supplemented, as necessary, with molecular features.

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.

Sarcomatoid Chromophobe Renal Cell Carcinoma with Heterologous Component

Clear cell renal cell carcinoma (RCC) is the most common malignant renal tumor in adults, while chromophobe RCC (CRCC) is the third most common. Any subtypes of RCC can undergo sarcomatoid differentiation, but heterologous differentiation in sarcomatoid area is very rare in RCC. Here a 61-year male is presented with hematuria and palpable mass. Clinicoradiologically, RCC was considered and left radical nephrectomy was performed. A well-circumscribed renal mass located in the upper pole of the left kidney with variegation and extensive areas of bony hard calcification noted, was reported as CRCC with sarcomatoid differentiation containing heterologous component. CRCC subtype has good prognosis but show dismal prognosis when associated with sarcomatous differentiation. We found 11 cases of sarcomatoid CRCC containing heterologous elements reported in indexed English literature. CRCC must be differentiated from Conventional RCC and Oncocytoma. The extensive sampling of the tumor is needed. We report a very rare case of CRCC with sarcomatoid differentiation containing heterologous elements.

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.

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.

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.

Prognostic impact of PD-1 and its ligands in renal cell carcinoma

Programmed death-1 receptor (PD-1) and programmed death-1 receptor-ligand (PD-L1) have been suggested to play a role as prognostic markers in clear cell renal cell carcinoma (ccRCC). The association between PD-L1 and prognosis seems to be more robust than for PD-1. Further, preliminary analyses suggest that neither PD-1 nor its ligands play a role as prognostic markers in non-clear cell RCC, while the prognostic role of PD-L2 in ccRCC as well as in non-clear cell RCC remains unclear.

Prognostic Factors for Renal Cell Carcinoma Subtypes Diagnosed According to the 2016 WHO Renal Tumor Classification: a Study Involving 928 Patients

The morphotype and grade of renal cell carcinoma (RCC) in 928 nephrectomies were reclassified according to the 2016 WHO classification in order to analyze the distribution and outcomes of RCC subtypes in Hungary, to assess whether microscopic tumor necrosis is an independent prognostic factor in clear cell RCC, and to study whether a two-tiered grading (low/high) for clear cell and papillary RCC provides similar prognostic information to that of the four-tiered ISUP grading system. 83.4% of the cohort were clear cell, 6.9% papillary, 4.5% chromophobe, 2.3% unclassified, 1.1% Xp11 translocation, 1.1% clear cell papillary, 0.3% collecting duct and 0.1% mucinous tubular and spindle cell RCCs. RCC occurred in 16 patients with end-stage kidney disease and none of them displayed features of acquired cystic kidney disease-associated RCC. The 5-year survival rates were as follows: chromophobe 100%, clear cell papillary 100%, clear cell low-grade 96%, papillary type 1 92%, clear cell high-grade 63%, papillary type 2 65%, unclassified 46%, Xp11 translocation 20%, and collecting duct 0%. The 5-year survival rates in low-grade and high-grade papillary RCC were 95% and 59%, respectively. In clear cell RCC, only the grade, the stage and the positive surgical margin proved to be independent prognostic factors statistically. Overall, papillary RCC occurred relatively infrequently; microscopic tumor necrosis in clear cell RCC did not predict the outcome independently of the tumor grading; and the assignment of clear cell and papillary RCCs into low-grade or high-grade tumors was in terms of survival no worse than the ISUP grading.

Differences in Overall and Cancer-specific Survival of Patients Presenting With Chromophobe Versus Clear Cell Renal Cell Carcinoma: A Propensity Score Matched Analysis

OBJECTIVES

To investigate prognostic parameters for the oncological outcome of patients treated for chromophobe renal cell carcinoma (chRCC) in comparison with patients treated for clear cell RCC (ccRCC) using propensity score matching for survival analysis.

METHODS

From 1969 to 2009, we identified 1010 from 3567 patients with RCC. Survival was analyzed using Kaplan-Meier estimate for histological subtypes including 109 chRCC and 901 ccRCC. Uni- and multivariate Cox regression was used to analyze prognostic factors for overall survival (OS) and cancer-specific survival (CSS). Propensity score matching was performed to adjust for differences in patient characteristics among histological subgroups.

RESULTS

The median follow-up was 61 months (range 0-289). chRCC showed longer OS (5 year, 90.1%; 10 year, 74.2%; 15 year, 61.4%) and CSS (94.2%, 89.7%, 89.7%) compared with ccRCC (OS 75.7%, 54.9%, 46.1% and CSS 84.7%, 75.4%, 72.2%; P = .002). Multivariate Cox regression revealed histology as a significant prognostic factor. Propensity score matching showed a difference in 72.4% (OS) and 87.2% (CSS) of matching attempts confirming the significant impact of histology. Univariate Cox regression showed nephron sparing surgery, no metastasis and no symptoms at presentation, age <65, eosinophilic features, low American Society of Anesthesiologists score, and Charlson Comorbidity Index to be beneficial for CSS. Only age at surgery, metastasis at presentation, and American Society of Anesthesiologists and Charlson Comorbidity Index scores were significant factors for OS in chRCC patients.

CONCLUSION

ChRCC appears to have a favorable outcome compared with ccRCC. Even after adjustment for differences in characteristics known to have an influence on survival by propensity score matching, histology remains a significant prognostic factor.