Chromophobe renal cell carcinoma: Novel molecular insights and clinicopathologic updates

Neuroendocrine gene subsets are uniquely dysregulated in prostate adenocarcinoma

Prostate cancer has heterogeneous growth patterns, and its prognosis is the poorest when it progresses to a neuroendocrine phenotype. Using bioinformatic analysis, we evaluated RNA expression of neuroendocrine genes in a panel of five different cancer types: prostate adenocarcinoma, breast cancer, kidney chromophobe, kidney renal clear cell carcinoma and kidney renal papillary cell carcinoma. Our results show that specific neuroendocrine genes are significantly dysregulated in these tumors, suggesting that they play an active role in cancer progression. Among others, synaptophysin (SYP), a conventional neuroendocrine marker, is upregulated in prostate adenocarcinoma (PRAD) and breast cancer (BRCA). Our analysis shows that SYP is enriched in small extracellular vesicles (sEVs) derived from plasma of PRAD patients, but it is absent in sEVs derived from plasma of healthy donors. Similarly, classical sEV markers are enriched in sEVs derived from plasma of prostate cancer patients, but weakly detectable in sEVs derived from plasma of healthy donors. Overall, our results pave the way to explore new strategies to diagnose these diseases based on the neuroendocrine gene expression in patient tumors or plasma sEVs.

Clear cell likelihood score may improve diagnosis and management of renal masses

The detection of solid renal masses has increased over time due to incidental findings during imaging studies conducted for unrelated medical conditions. Approximately 20% of lesions measuring less than 4 cm are benign and 80% are malignant. Clear cell renal cell carcinoma (ccRCC) is the most frequent among renal carcinomas, responsible for 65-80% of cases. The increased detection of renal masses facilitates early diagnosis and treatment. However, it also leads to more invasive interventions, which result in higher morbidity and costs. Currently, only histological analysis can offer an accurate diagnosis. Surgical nephron loss significantly elevates morbidity and mortality rates. Active surveillance represents a conservative management approach for patients diagnosed with a solid renal mass that is endorsed by both American Urological Association and the European Society for Medical Oncology. However, active surveillance is used in a minority of patients and varies across institutions. The lack of clinical studies using a standardized approach to incidentally detected small renal masses precludes the widespread use of active surveillance. Hence, there is an urgent need for better patient selection, distinguishing those who require surgery from those suitable for active surveillance. The clear cell likelihood score (ccLS) represents a novel MRI tool for assessing the probability of a renal mass being a ccRCC. In this study, we present a comprehensive review of renal masses and their evaluation using the ccLS to facilitate shared decision between urologists and patients.

Renal cell carcinoma histologic subtypes exhibit distinct transcriptional profiles

Molecular profiling of clear cell renal cell carcinoma (ccRCC) tumors of patients in a clinical trial has identified distinct transcriptomic signatures with predictive value, yet data in non-clear cell variants (nccRCC) are lacking. We examined the transcriptional profiles of RCC tumors representing key molecular pathways, from a multi-institutional, real-world patient cohort, including ccRCC and centrally reviewed nccRCC samples. ccRCC had increased angiogenesis signature scores compared with the heterogeneous group of nccRCC tumors, while cell cycle, fatty acid oxidation/AMPK signaling, and fatty acid synthesis/pentose phosphate signature scores were increased in one or more nccRCC subtypes. Among both ccRCC and nccRCC tumors, T effector scores statistically correlated with increased immune cell infiltration and were more commonly associated with immunotherapy-related markers (PD-L1+/TMBhi/MSIhi). In conclusion, this study provides evidence of differential gene transcriptional profiles among ccRCC versus nccRCC tumors, providing insights for optimizing personalized and histology-specific therapeutic strategies for patients with advanced RCC.

Chromophobe Renal Cell Carcinoma With Extensive Retraction Artifact: A Potential Diagnostic Pitfall From Micropapillary Urothelial Carcinoma

In addition to "classic" and eosinophilic subtype, chromophobe renal cell carcinoma (RCC) is well-known to demonstrate various morphological patterns including adenomatoid, microcystic, pigmented, multicystic, papillary, neuroendocrine-like, and small cell-like, all of which are important to appreciate for accurate diagnosis. Herein, we expand on a unique chromophobe RCC morphology not previously described consisting of tumor cells with extensive stromal retraction, mimicking upper urothelial tract micropapillary carcinoma (MPC). Twelve MPC-like chromophobe RCC nephrectomies were reviewed with clinicopathological features recorded; molecular testing was performed on 7 of 12 tumors. Patients were mostly men (n=10) with a mean age of 65 years. Mean tumor size was 6.4 cm with pathological stage distribution as follows: 4 (33%) T1a, 2 (17%) T1b, 1 (8%) T2b, and 3 (25%) T3a. The extent of MPC-like chromophobe RCC foci ranged from 10% to 40% (mean=26%; there was no correlation between the extent of MPC-like chromophobe RCC foci and tumor stage). Other chromophobe RCC morphological patterns were not identified. When performed, all (100%) tumors depicted prototypic chromophobe RCC staining pattern of KIT positivity/KRT7 positivity. Molecular showed 6 of 7 (86%) with multiple chromosomal losses. Clinically significant mutations were identified in NF1, TP53, FLCN (likely somatic), CHEK2, and ZFHX3 genes. Follow up available in 9 patients showed no evidence of disease (mean=23 months). Although the etiology behind the extensive stromal retraction in our tumors is unknown, this may likely be artifactual in nature. Nonetheless, it is important to include MPC-like chromophobe RCC in the spectrum of "variant" morphologies to avoid diagnostic pitfalls from micropapillary carcinoma.

Chromophobe Renal Cell Carcinoma with Sarcomatoid Differentiation: Clinicopathologic Correlation and Molecular Findings

Introduction: Sarcomatoid differentiation has been reported in approximately 8% of chromophobe renal cell carcinoma (RCC) and is associated with a worse prognosis. We aim to describe the clinicopathologic and molecular findings of chromophobe RCC with sarcomatoid differentiation. Methods: Surgical pathology database was searched to identify chromophobe RCC with sarcomatoid differentiation from January 2015 to December 2021. Results: Five patients were diagnosed with chromophobe RCC with sarcomatoid differentiation. The median age at the time of diagnosis was 57 years (range 51-61 years). Three patients died after median follow-up of 12.1 months (range 1.6-18.2 months). The median tumor size was 10.7 cm (range 5.6-13.6 cm). The median percentage of sarcomatoid component was 60% (range 10-90%), and the median percentage of necrosis was 30% (range 10-50%). One tumor demonstrated osteoid formation. PAX8, keratin 7, KIT (CD117), and Hale colloidal iron were positive in the epithelial component, whereas the sarcomatoid component was positive for vimentin, CD10, and high Ki67 proliferative index. Molecular testing was performed in three specimens: all were TP53 mutated and microsatellite stable. One aggressive tumor had RB1 frameshift mutation and copy number gains for TERT and CUL4A. Conclusion: Chromophobe RCC with sarcomatoid differentiation is a rare entity with aggressive behavior. Percentage of sarcomatoid component, necrosis, and the occurrence of metastasis is associated with worse prognosis. Molecular profiling reveals frequent TP53 mutation. While TERT promoter mutation has no prognostic implication, FLCN inactivation may be associated with a less aggressive course. The clinical significance of RB1 loss is unclear.

Clinicopathological, Immunohistochemical, and Molecular Characteristics of Pigmented Microcystic Chromophobe Renal Cell Carcinoma with Favorable Prognosis

Background. Pigmented microcystic chromophobe renal cell carcinoma (RCC) is a subtype of chromophobe RCC. Its distinct histopathologic features are microcystic and microtubular pattern, pigmentation, and microcalcifications. Pigmented microcystic chromophobe RCC has ultrastructure, immunophenotypic structure, and molecular results similar to chromophobe RCC. Methods. We report five tumors of pigmented microcystic chromophobe RCC. Morphological observation and immunohistochemical examination were performed, and clinical and molecular features were analyzed. Results. Microscopically, all five tumors showed brown pigmentation, microcystic, and tubular cystic structures, one tumor presented microscopic calcifications. All tumors were positive for EMA, AE1/AE3, PAX8, KRT7, KIT (CD117), claudin 7, KRT8, and E-cadherin, and three tumors expressed P504S. All tumors were negative for vimentin, CA9, KRT20, TFE3, TFEB, Melan-A, HMB45, FH, SDHB, and GATA3. Ki-67 index varied from less than 1% to 2%. In three tumors, next-generation sequencing of the 688 gene was performed, the results found gene variants with potential clinical significance such as JMJD1C, MYCL, TP53, PI3KCA, KRAS, APC, GLI1, LRRK2, and gene variants with unclear clinical significance such as NTRK1 and RAD50; All patients remained alive over a follow-up period of 8-46 months without tumor recurrence and sarcomatoid transformation. Conclusions. Pigmented microcystic chromophobe RCC has a relatively benign biological behavior, and distant metastases and sarcomatoid transformation are rare. This overview of five additional tumors of pigmented microcystic chromophobe RCC offers further insight into this special subtype of chromophobe RCC.

The incidence, pathogenesis, and management of non-clear cell renal cell carcinoma

Renal cell carcinoma (RCC) is the most common type of kidney cancer and is divided into two distinct subtypes, clear cell renal cell carcinoma (ccRCC) and non-clear cell renal cell carcinoma (nccRCC). Although many treatments exist for RCC, these are largely based on clinical trials performed in ccRCC and there are limited studies on the management of nccRCC. Non-clear cell RCC consists of multiple histological subtypes: papillary, chromophobe, translocation, medullary, collecting duct, unclassified, and other rare histologies. Due to variations in pathogenesis and therapeutic response, therapy should be tailored to specific variant histologies. For patients with localized nccRCC, surgical resection remains the gold standard. In the metastatic setting, the standard of care has yet to be clearly defined, and most guidelines recommend clinical trial participation. General therapeutic options include immunotherapy, either as monotherapy or in combination, targeted therapies such as vascular endothelial growth factor tyrosine kinase inhibitors and MET inhibitors, and chemotherapy in certain subtypes. Here we present a review of the incidence and pathogenesis of the various subtypes, as well as available clinical data to support therapeutic recommendations for these subtypes. We also highlight currently available clinical trials in nccRCC and future directions in investigating novel treatment modalities tailored to patients with variant histology.

Evaluation of an institutional series of low-grade oncocytic tumor (LOT) of the kidney and review of the mutational landscape of LOT

The 2022 WHO classification of urinary and male genital tumors introduced several novel kidney entities exhibiting eosinophilic/oncocytic features with specific mutational backgrounds. Thus, molecular techniques, such as next-generation sequencing (NGS), became more commonly used for their evaluation. We studied 12 low-grade oncocytic tumors (LOT) of the kidney (from 11 patients), identified in a cohort of 210 eosinophilic/oncocytic renal tumors, diagnosed in our institution between October 2019 and May 2023, which represented 5.7% (12/210) of all eosinophilic/oncocytic renal tumors during this period. We reviewed their clinicopathologic, histologic, and immunohistochemical features, as well as their mutational profiles. We also reviewed the literature on NGS-derived data of LOT, by selecting papers in which LOT diagnosis was rendered according to the criteria proposed initially. Median age was 65 years (mean: 63.5; range 43-79) and median tumor size was 2.0 cm (mean: 2.2; range: 0.9-3.1). All tumors were positive for PAX8, CK7, and GATA3, and negative or focally positive for CD117/KIT. We found the following gene mutations: MTOR ((6/11), 54.5%)), TSC1 ((2/11), 18.2%)), and 1 had both NOTCH1 and NOTCH4 ((1/11), 9.1%)). Wild-type status was found in 2/11 (18.2%) patients and one tumor was not analyzable. A review of 8 previous studies that included 79 LOTs revealed frequent mutations in the genes that regulate the mammalian target of rapamycin (mTOR) pathway: MTOR (32/79 (40.5%)), TSC1 (21/79 (26.6%)), and TSC2 (9/79 (11.4%)). Other mutated genes included PIK3CA, NF2, and PTEN, not typically known to affect the mTOR pathway, but potentially acting as upstream and downstream effectors. Our study shows that LOT is increasingly diagnosed in routine practice when applying the appropriate diagnostic criteria. We also confirm that the mTOR pathway is strongly implicated in the pathogenesis of this tumor mainly through MTOR, TCS1, and TSC2 mutations, but other genes could also be involved in the pathway activation, especially in LOTs without "canonical" mutations.

Biomarkers in renal cell carcinoma and their targeted therapies: a review

Renal cell carcinoma (RCC) is one of the most life-threatening urinary malignancies displaying poor response to radiotherapy and chemotherapy. Although in the recent past there have been tremendous advancements in using targeted therapies for RCC, despite that it remains the most lethal urogenital cancer with a 5-year survival rate of roughly 76%. Timely diagnosis is still the key to prevent the progression of RCC into metastatic stages as well as to treat it. But due to the lack of definitive and specific diagnostic biomarkers for RCC and its asymptomatic nature in its early stages, it becomes very difficult to diagnose it. Reliable and distinct molecular markers can not only refine the diagnosis but also classifies the tumors into thier sub-types which can escort subsequent management and possible treatment for patients. Potential biomarkers can permit a greater degree of stratification of patients affected by RCC and help tailor novel targeted therapies. The review summarizes the most promising epigenetic [DNA methylation, microRNA (miRNA; miR), and long noncoding RNA (lncRNA)] and protein biomarkers that have been known to be specifically involved in diagnosis, cancer progression, and metastasis of RCC, thereby highlighting their utilization as non-invasive molecular markers in RCC. Also, the rationale and development of novel molecular targeted drugs and immunotherapy drugs [such as tyrosine kinase inhibitors and immune checkpoint inhibitors (ICIs)] as potential RCC therapeutics along with the proposed implication of these biomarkers in predicting response to targeted therapies will be discussed.

Characterization of Intercalated Cell Markers KIT and LINC01187 in Chromophobe Renal Cell Carcinoma and Other Renal Neoplasms

Introduction. Chromophobe renal cell carcinoma (chromophobe RCC) is the third major subcategory of renal tumors after clear cell RCC and papillary RCC, accounting for approximately 5% of all RCC subtypes. Other oncocytic neoplasms seen commonly in surgical pathology practice include the eosinophilic variant of chromophobe RCC, renal oncocytoma, and low-grade oncocytic unclassified RCC. Methods. In our recent next-generation sequencing based study, we nominated a lineage-specific novel biomarker LINC01187 (long intergenic non-protein coding RNA 1187) which was found to be enriched in chromophobe RCC. Like KIT (cluster of differentiation 117; CD117), a clinically utilized chromophobe RCC related biomarker, LINC01187 is expressed in intercalated cells of the nephron. In this follow-up study, we performed KIT immunohistochemistry and LINC01187 RNA in situ hybridization (RNA-ISH) on a cohort of chromophobe RCC and other renal neoplasms, characterized the expression patterns, and quantified the expression signals of the two biomarkers in both primary and metastatic settings. Results. LINC01187, in comparison to KIT, exhibits stronger and more uniform expression within tumors while maintaining temporal and spatial consistency. LINC01187 also is devoid of intra-tumoral heterogeneous expression pattern, a phenomenon commonly noted with KIT. Conclusions. LINC01187 expression can augment the currently utilized KIT assay and help facilitate easy microscopic analyses in routine surgical pathology practice.

High Expression of DNTTIP1 Predicts Poor Prognosis in Clear Cell Renal Cell Carcinoma

Background

Invasion and metastasis led to poor prognosis and death of clear cell renal cell carcinoma (ccRCC) patients. The deoxynucleotidyl transferase terminal interacting protein 1 (DNTTIP1) was reported to promote multiple tumor progression. However, there is no research about DNTTIP1 in ccRCC.

Methods

Kaplan-Meier survival analysis, multivariate analysis demonstrated the prognostic indicator in overall survival (OS) and disease-free survival (DFS) of ccRCC with DNTTIP1 expression in the Cancer Genome Atlas Kidney Clear Cell Carcinoma (TCGA-KIRC). Receiver operator characteristic (ROC) curve analyzed diagnostic ability of DNTTIP1 in TCGA-KIRC and validation dataset. The quantitative real-time polymerase chain reaction (qRT-PCR) detected the DNTTIP1 expression in renal cancer tissues, and the Office of Cancer Clinical Proteomics Research (CPTAC) verified the protein expression of DNTTIP1. Moreover, nomogram predicted the role of DNTTIP1 in ccRCC patient. Single-sample Gene Set Enrichment Analysis (SsGSEA) and GSEA evaluated the pathogenesis role of DNTTIP1 in TCGA-KIRC.

Results

DNTTIP1 expression was higher in ccRCC tumor tissues. High expression of DNTTIP1 was associated with poor OS (HR = 1.618, P < 0.0001), and poor DFS (HR = 1.789, P < 0.0001). SsGSEA and GSEA showed DNTTIP1 was associated with hypoxia, epithelial-mesenchymal transition (EMT), angiogenesis, G2M checkpoint. DNTTIP1 had a positive correlation with EMT biomarkers in ccRCC, and might be an effective target for ccRCC.

Conclusion

This study provided that higher expression of DNTTIP1 predicted poor prognosis in ccRCC, and DNTTIP1 might be a novel detection biomarker and therapeutic target of tumor malignant in the future.

Whole-Lesion CT Texture Analysis as a Quantitative Biomarker for the Identification of Homogeneous Renal Tumors

Renal tumors are very common in the urinary system, and the preoperative differential diagnosis of homogeneous renal tumors remains a challenge. This study aimed to evaluate the feasibility of the whole-lesion CT texture analysis for the identification of homogeneous renal tumors including clear cell renal cell carcinoma (ccRCC), chromophobe RCC (chRCC), and renal oncocytoma (RO). This retrospective study was approved by our local IRB. Contrast-enhanced CT examination was performed in 128 patients and histopathologically confirmed ccRCC, chRCC, and RO. The one-way ANOVA test with Bonferroni corrections was used to compare the differences, and the receiver operating characteristic (ROC) curve analysis was applied to determine the diagnostic efficiency. The whole-lesion CT histogram analysis was used to demonstrate significant differences between ccRCC and chRCC in both arterial and venous phases, and the entropy demonstrated excellent performance in discriminating these two types of tumors (AUCs = 0.95, 0.91). The inhomogeneity of ccRCC was significantly higher than that of RO both in arterial and venous phases. The entropy of chRCC was significantly lower than that of RO, and the kurtosis and entropy yielded high sensitivity (91%) and moderate specificity (74%) in the arterial phase. The whole-lesion CT histogram analysis could be useful for the differential diagnosis of homogeneous ccRCC, chRCC, and RO.

Characteristics of renal oncocytomas and clinical novelties: Single center experience of 17 years

Objective:

To assess the characteristics of renal oncocytomas and the clinical outcomes of patients in the last 17 years in our institution.

Methodology:

The medical records of the patients who underwent partial and radical nephrectomy from May 2004 to December 2021 were evaluated retrospectively. Radiology and pathology results were evaluated. Patients diagnosed with oncocytoma after surgery were included in the study.

Results:

Out of 791 patients who were operated for renal masses, 55 patients with the diagnosis of oncocytoma were included in the study, 17 of them were female. The mean age of the patients was 64.77 ± 10.58 years. Open and laparoscopic methods were applied to patients. Partial nephrectomy was performed in 25 patients (46.2%). It was observed that none of the patients with a mean follow-up of 76 months developed recurrence or death due to oncocytoma.

Conclusion:

Oncocytoma is a benign and rare tumor of the kidney which distinguishing it from malign tumors preoperatively with recent techniques is impossible. Especially in small sized tumors, considering the possibility of oncocytoma, nephron sparing surgery should be preferred in terms of patients’ benefit. Further research is needed for the novel imaging techniques and biomarkers proposed to be used in routine use to distinguish oncocytoma.

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.