A systematic review and meta-analysis of immunohistochemical biomarkers that differentiate chromophobe renal cell carcinoma from renal oncocytoma

Scars Run Deep: Problematic Morphology and Immunoprofile of Scars in Renal Oncocytomas

In some instances, the central scar of renal oncocytoma can demonstrate entrapped cells with unusual morphology and aberrant immunoprofile creating potential diagnostic confusion. Herein, 100 renal oncocytomas containing scars with embedded epithelial cells were identified from 6 institutions, including nephrectomies (64% partial, 36% radical) of similar laterality (left = 51%) and sex distribution (male = 56%), with patient ages ranging from 38 to 86 years (mean = 64.3years) and tumor sizes ranging from 2 to 16 cm (mean = 5.3 cm). Immunohistochemistry was performed on all tumors for KRT7, KIT, vimentin, and CA9 with staining intensity and extensity separately analyzed. Of 4 architectural patterns of cells within the scar, 60% showed tubular pattern. Of 4 cytologies within the scar, flat/elongated (49%) and cuboidal cells (40%) predominated. Within the scar, 62% showed eosinophilic cytoplasm, with 38% showing both cleared and eosinophilic cytoplasm; notably, 79% showed higher grade nuclei than typical oncocytes. A subset of scar cells showed mucinous-like basophilic secretions (19%). Compared to background renal oncocytoma, tumor cells within the scar were more often positive for vimentin, KRT7, and CA9 and more frequently negativity for KIT. Specifically, of the notable "aberrant" immunoprofiles, 79% showed KRT7 positivity/KIT negativity/vimentin positive, 84% showed vimentin positivity/CA9 positivity, and 78% showed KIT negativity/vimentin positivity/CA9 positivity. While encountering scars within renal oncocytomas is not uncommon, what is not well appreciated is the unique morphology and immunohistochemistry of tumor cells within the scar. Comparing tumor morphology and immunoprofile of the scar to the background oncocytoma is helpful to avoid interpretative confusion.

Pancreatic Cancer and Detection Methods

The pancreas is a vital organ with exocrine and endocrine functions. Pancreatitis is an inflammation of the pancreas caused by alcohol consumption and gallstones. This condition can heighten the risk of pancreatic cancer (PC), a challenging disease with a high mortality rate. Genetic and epigenetic factors contribute significantly to PC development, along with other risk factors. Early detection is crucial for improving PC outcomes. Diagnostic methods, including imagining modalities and tissue biopsy, aid in the detection and analysis of PC. In contrast, liquid biopsy (LB) shows promise in early tumor detection by assessing biomarkers in bodily fluids. Understanding the function of the pancreas, associated diseases, risk factors, and available diagnostic methods is essential for effective management and early PC detection. The current clinical examination of PC is challenging due to its asymptomatic early stages and limitations of highly precise diagnostics. Screening is recommended for high-risk populations and individuals with potential benign tumors. Among various PC screening methods, the N-NOSE plus pancreas test stands out with its high AUC of 0.865. Compared to other commercial products, the N-NOSE plus pancreas test offers a cost-effective solution for early detection. However, additional diagnostic tests are required for confirmation. Further research, validation, and the development of non-invasive screening methods and standardized scoring systems are crucial to enhance PC detection and improve patient outcomes. This review outlines the context of pancreatic cancer and the challenges for early detection.

A Giant Oncocytoma in an Elderly Female Patient: A Case Report

Renal oncocytomas are rare, benign tumors that can be difficult to distinguish from malignant renal cell carcinomas. This case report presents an 84-year-old woman with a sizeable renal oncocytoma and discusses this rare entity's diagnostic challenges and management.

A case of primary optic pathway demyelination caused by oncocytic oligodendrogliopathy of unknown origin

We report the case of a 22-year-old woman presenting with an acute onset of dizziness, gait dysbalance and blurred vision. Magnetic resonance imaging included 3 Tesla and 7 Tesla imaging and revealed a T2-hyperintense, T1-hypointense, non-contrast-enhancing lesion strictly confined to the white matter affecting the right optic radiation. An extensive ophthalmologic examination yielded mild quadrantanopia but no signs of optic neuropathy. The lesion was biopsied. The neuropathological evaluation revealed a demyelinating lesion with marked tissue vacuolization and granular myelin disintegration accompanied by mild T cell infiltration and a notable absence of myelin uptake by macrophages. Oligodendrocytes were strikingly enlarged, displaying oncocytic characteristics and showed cytoplasmic accumulation of mitochondria, which had mildly abnormal morphology on electron microscopy. The diagnosis of multiple sclerosis was excluded. Harding's disease, a variant of Leber's hereditary optic neuropathy, was then suspected. However, neither PCR for relevant mutations nor whole exome sequencing yielded known pathogenetic mutations in the patient's genome. We present a pattern of demyelinating tissue injury of unknown etiology with an oncocytic change of oligodendrocytes and a lack of adequate phagocytic response by macrophages, which to the best of our knowledge, has not been described before.

Low grade oncocytic tumors of the kidney: a clinically relevant approach for the workup and accurate diagnosis

Renal oncocytoma and chromophobe renal cell carcinoma were accepted as unique renal tumors in the late 1990s. Since their formal description, criteria for diagnosis have evolved and additional distinct tumor subtypes originally considered as one these two entities are now recognized. The last two decades have witnessed unprecedented interest in the spectrum of low grade oncocytic renal neoplasms in three specific areas: (1) histologic characterization of tumors with overlapping morphologic features between oncocytoma and chromophobe renal cell carcinoma; (2) description of potentially unique entities within this spectrum, such as eosinophilic vacuolated tumor and low-grade oncocytic tumor; and (3) better appreciation of the association between a subset of low grade oncocytic tumors and hereditary renal neoplasia. While this important work has been academically rewarding, the proposal of several histologic entities with overlapping morphologic and immunophenotypic features (which may require esoteric adjunctive immunohistochemical and/or molecular techniques for confirmation) has created frustration in the diagnostic pathology and urology community as information evolves regarding classification within this spectrum of renal neoplasia. Pathologists, including genitourinary subspecialists, are often uncertain as to the "best practice" diagnostic approach to such tumors. In this review, we present a practical clinically relevant algorithmic approach to classifying tumors within the low grade oncocytic family of renal neoplasia, including a proposal for compressing terminology for evolving categories where appropriate without sacrificing prognostic relevance.

A triple-classification for differentiating renal oncocytoma from renal cell carcinoma subtypes and CK7 expression evaluation: a radiomics analysis

Background

To investigate the value of computed tomography (CT)-based radiomics model analysis in differentiating renal oncocytoma (RO) from renal cell carcinoma subtypes (chromophobe renal cell carcinoma, clear cell carcinoma) and predicting the expression of Cytokeratin 7 (CK7).

Methods

In this retrospective study, radiomics was applied for patients with RO, chRCC and ccRCC who underwent surgery between January 2013 and December 2019 comprised the training cohort, and the testing cohort was collected between January and October 2020. The corticomedullary (CMP) and nephrographic phases (NP) were manually segmented, and radiomics texture parameters were extracted. Support vector machine was generated from CMP and NP after feature selection. Shapley additive explanations were applied to interpret the radiomics features. A radiomics signature was built using the selected features from the two phases, and the radiomics nomogram was constructed by incorporating the radiomics features and clinical factors. Receiver operating characteristic curve was calculated to evaluate the above models in the two sets. Furthermore, Rad-score was used for correlation analysis with CK7.

Results

A total of 123 patients with RO, chRCC and ccRCC were analyzed in the training cohort and 57 patients in the testing cohort. Subsequently, 396 radiomics features were selected from each phase. The radiomics features combining two phases yielded the highest area under the curve values of 0.941 and 0.935 in the training and testing sets, respectively. The Pearson’s correlation coefficient was statistically significant between Rad-score and CK7.

Conclusion

We proposed a non-invasive and individualized CT-based radiomics nomogram to differentiation among RO, chRCC and ccRCC preoperatively and predict the immunohistochemical protein expression for accurate clinical diagnosis and treatment decision.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12894-022-01099-0.

Do we need an updated classification of oncocytic renal tumors? : Emergence of low-grade oncocytic tumor (LOT) and eosinophilic vacuolated tumor (EVT) as novel renal entities

The category of "oncocytic renal tumors'' includes well-recognized entities, such as renal oncocytoma (RO) and eosinophilic variant of chromophobe renal cell carcinoma (eo-ChRCC), as well as a group of "gray zone" oncocytic tumors, with overlapping features between RO and eo-ChRCC that create ongoing diagnostic and classification problems. These types of renal tumors were designated in the past as "hybrid oncocytoma-chromophobe tumors". In a recent update, the Genitourinary Pathology Society (GUPS) proposed the term "oncocytic renal neoplasm of low malignant potential, not further classified", for such solitary and sporadic, somewhat heterogeneous, but relatively indolent tumors, with equivocal RO/eo-ChRCC features. GUPS also proposed that the term "hybrid oncocytic tumor" be reserved for tumors found in a hereditary setting, typically arising as bilateral and multifocal ones (as in Birt-Hogg-Dubé syndrome). More recent developments in the "gray zone" of oncocytic renal tumors revealed that potentially distinct entities may have been "hidden" in this group. Recent studies distinguished two new entities: "Eosinophilic Vacuolated Tumor" (EVT) and "Low-grade Oncocytic Tumor" (LOT). The rapidly accumulated evidence on EVT and LOT has validated the initial findings and has expanded the knowledge on these entities. Both are uniformly benign and are typically found in a sporadic setting, but rarely can be found in patients with tuberous sclerosis complex. Both have readily distinguishable morphologic and immunohistochemical features that separate them from similar renal tumors, without a need for detailed molecular studies. These tumors very frequently harbor TSC/MTOR mutations that are however neither specific nor restricted to these two entities. In this review, we outline a proposal for a working framework on how to classify such low-grade oncocytic renal tumors. We believe that such framework will facilitate their handling in practice and will stimulate further discussions and studies to fully elucidate their spectrum.

Oncocytic renal neoplasms with diffuse keratin 7 immunohistochemistry harbor frequent alterations in the mammalian target of rapamycin pathway

Low-grade oncocytic tumor (LOT) has been recently proposed as a unique renal tumor. However, we have encountered tumors with more oncocytoma-like morphology that show diffuse keratin 7 reactivity, which we sought to characterize molecularly. Eighteen tumors with a diffuse keratin 7 positive and KIT negative pattern were identified from 184 with predominantly oncocytoma-like histology. These tumors were subjected to detailed immunohistochemical evaluation and 14 were evaluated using the Illumina^® HiSeq 4000 platform for 324 cancer-associated genes. Patients' ages ranged from 39 to 80 (median = 59.5 years) with a male to female ratio of 1.25:1. Morphology was predominantly oncocytoma-like with discrete nests, compared to the solid and edematous patterns described in LOT. Other than positive keratin 7 and negative KIT, the tumor cells were positive for PAX8, E-cadherin, AE1/AE3, Ber-EP4, AMACR, CD10, and MOC31, and were negative for other studied markers. FH and INI1 were normal. Eleven of 14 harbored genomic abnormalities, likely sporadic, primarily involving the MTOR pathway (73%). Overall, the alterations included MTOR activating mutation (n = 1), TSC1 inactivating mutation (n = 1), TSC2 mutation (p.X534 splice site, n = 1), STK11 (a negative regulator of the MTOR pathway) mutation (n = 1), both STK11 and TSC1 mutations (n = 1), biallelic loss of PTEN and TSC1 deletion (n = 1), and MET amplification and TSC1 inactivating mutation (n = 1). Amplification of FGFR3 was identified in one additional tumor. Other alterations included FOXP1 loss (n = 1), NF2 E427 homozygous loss (n = 1), and PI3KCA activating mutation (n = 1). At a median follow-up of 68 months (2-147 months) for 15 patients, all were alive without disease. Oncocytic renal tumors with diffuse keratin 7 labeling show frequent alterations in the TSC/MTOR pathway, despite more oncocytoma-like morphology than initially described in LOT, likely expanding the morphologic spectrum of the latter.

Low-grade oncocytic renal tumor (LOT): mutations in mTOR pathway genes and low expression of FOXI1

Low-grade oncocytic renal tumor (LOT) is an emerging provisional entity, described as rare solid renal oncocytic/eosinophilic tumor sharing diffuse CK7 and negative CD117 immunoprofile. The links between LOT and other eosinophilic chromophobe like-renal cell carcinomas (RCC) are currently discussed. We sequenced tumoral DNA with a next generation sequencing panel for kidney cancer and carried out immunohistochemical analyses with CK7, CD117, SDHB, 4EBP1-P, S6K-P, and FOXI1 antibodies in a series of ten cases of LOT (9 females, 1 male; mean age at surgery: 66 years, 42.3 to 83.4) retrospectively diagnosed from a cohort of 272 tumors initially classified as chromophobe RCC (CHRCC). All LOT were single, without known hereditary predisposition, classified stage pT1 (70%), pT2 (20%) or pT3a (10%). Morphological features were similar to previous descriptions and clinical behavior was indolent for the six cases with available follow-up. We identified genetic variations in mTOR pathway related genes in 80% of cases, MTOR (7 cases) or TSC1 (1 case). Expression of FOXI1 was absent in all cases. In 9 LOT, 4EBP1-P and S6K-P were overexpressed, suggesting mTOR pathway activation.Our data highlights the major role of mTOR pathway in tumorigenesis of LOT mostly due to activating MTOR gene variations. Absence of FOXI1 expression is a strong argument to distinguish LOT from eosinophilic CHRCC and to bring them closer to other recently described FOXI1 negative eosinophilic-CHRCC like with MTOR/TSC mutations. Altogether, our data argue to consider LOT as a distinct entity with a favorable clinical outcome. However, in case of metastasis, an accurate diagnosis of LOT would be essential for the patient's management and could allow targeted therapy.

Review of Immunohistochemistry Biomarkers in Pancreatic Cancer Diagnosis

Pancreatic cancer is one of the cancer types with poor prognosis and high rate of mortality. Diagnostic modalities for early detection of pancreatic cancer have been among the academic concerns. On account of the potential role of immunohistochemistry (IHC) biomarkers in overcoming certain limitations of imaging diagnostic tools in discriminating pancreatic cancer tissues from benign ones, a growing scholarly attention has been given to the diagnostic efficacy of IHC biomarkers for pancreatic cancer. This review will analyze and synthesize published articles to provide an insight into potential IHC biomarkers for pancreatic cancer diagnosis.

Symptomatic giant renal oncocytoma with an incidental papillary adenoma

Renal oncocytomas are benign, slow-growing tumours accounting for 3-7% of all solid renal neoplasms. These tumours tend to be small, unilateral and asymptomatic and are often discovered incidentally on imaging. Large oncocytomas are rare and can be difficult to distinguish from renal cell carcinoma based off clinical findings or imaging characteristics alone. Papillary adenomas are also benign renal neoplasms but arising from the renal tubular epithelium and almost always located within the cortex. We present a case of a 63-year-old Caucasian male with a large symptomatic renal oncocytoma with an incidental concurrent papillary adenoma.

Absolute quantitative proteomics using the total protein approach to identify novel clinical immunohistochemical markers in renal neoplasms

BACKGROUND

Renal neoplasms encompass a variety of malignant and benign tumors, including many with shared characteristics. The diagnosis of these renal neoplasms remains challenging with currently available tools. In this work, we demonstrate the total protein approach (TPA) based on high-resolution mass spectrometry (MS) as a tool to improve the accuracy of renal neoplasm diagnosis.

METHODS

Frozen tissue biopsies of human renal tissues [clear cell renal cell carcinoma (n = 7), papillary renal cell carcinoma (n = 5), chromophobe renal cell carcinoma (n = 5), and renal oncocytoma (n = 5)] were collected for proteome analysis. Normal adjacent renal tissue (NAT, n = 5) was used as a control. Proteins were extracted and digested using trypsin, and the digested proteomes were analyzed by label-free high-resolution MS (nanoLC-ESI-HR-MS/MS). Quantitative analysis was performed by comparison between protein abundances of tumors and NAT specimens, and the label-free and standard-free TPA was used to obtain absolute protein concentrations.

RESULTS

A total of 205 differentially expressed proteins with the potential to distinguish the renal neoplasms were found. Of these proteins, a TPA-based panel of 24, including known and new biomarkers, was selected as the best candidates to differentiate the neoplasms. As proof of concept, the diagnostic potential of PLIN2, TUBB3, LAMP1, and HK1 was validated using semi-quantitative immunohistochemistry with a total of 128 samples assessed on tissue micro-arrays.

CONCLUSIONS

We demonstrate the utility of combining high-resolution MS and the TPA as potential new diagnostic tool in the pathology of renal neoplasms. A similar TPA approach may be implemented in any cancer study with solid biopsies.

The Role of CK7, S100A1, and CD82 (KAI1) Expression in the Differential Diagnosis of Chromophobe Renal Cell Carcinoma and Renal Oncocytoma

Renal oncocytoma is a benign renal tumor originated from intercalated cells of collecting ducts like chromophobe renal cell carcinoma (RCC). The differential diagnosis of these 2 tumors is important because while they are histologically and cytologically similar, they show different biological behavior. For the differential diagnosis, several immunohistochemical markers have been investigated. But, differential diagnostic challenges remain and the identification of additional markers is needed. Cytokeratin 7 (CK7) is one of ductal-type keratins, which is expressed in tumors of breast, pancreas, lung, thyroid, ovary, endometrium, urinary bladder, and the kidney. S100A1 is the first defined member of the calcium-binding S100 protein family and it organizes several cellular functions including cell cycle progression and cell differentiation.CD82 is a tetraspanin membrane protein, which functions as a metastasis supressor. In this study, we immunohistochemically investigated the expressions of CK7, S100A1, and CD82 in 30 chromophobe RCC (23 classic and 7 eosinophilic variant) and 19 oncocytomas. When these markers were evaluated separately and together, their expressions in chromophobe RCC and renal oncocytoma show statistically significant difference (P<0.001). Similar statistically significant results were also seen between eosinophilic chromophobe RCC and oncocytoma (P<0.001). For both classic and eosinophilic-variant chromophobe RCCs, CK7+/S100A1-/CD82+ profile being the most common. In oncocytomas, the most frequently observed profile was CK7-/S100A1+/CD82-. Our results showed that the application of a panel consisting of CK7, S100A1, and CD82 may provide accurate categorization of the tumors in difficult cases.

Diagnostic utility of amylase α-1A, MOC 31, and CD 82 in renal oncocytoma versus chromophobe renal cell carcinoma

Objective

Renal oncocytoma (RO) and chromophobe renal cell carcinoma (ChRCC) originate from the same cell origin, that is, the intercalated cells of the collecting duct.^[1] In most cases, there are clear morphologic differences between RO and ChRCC; however, in some instances, overlapping features may be encountered and the differentiation between the two entities becomes difficult.^[2] Several immunohistochemical markers with different expression patterns in ChRCC and RO have been described to rule out this dilemma.

Materials and Methods

About 47 primary renal neoplasms that had been diagnosed as RO or ChRCC were submitted for immunohistochemical staining of amylase α-1A (AMY1A), MOC 31, and CD 82. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy have been analyzed.

Results

AMY1A positivity was observed in all RO cases in our work with 91.7% sensitivity and 100% specificity in the diagnosis of RO. The PPV of its expression was (100%) and NPV (97.2%) with a diagnostic accuracy of 97.9%. A significant high expression of MOC 31 was observed in ChRCC compared to its expression in RO with a statistical significance (P < 0.001). In addition, we obtained 82.9% sensitivity and 91.7% specificity of MOC 31 expression in the diagnosis of ChRCC. The positive predictive value (PPV) was (96.7%), negative predictive value (NPV) (64.7%) with diagnostic accuracy (85.1%). In our studied cases, we detected positive immunoexpression of CD 82 in 10 cases (83.3%) of ChRCC. However, it was lost in all RO cases (100%). CD 82 sensitivity and specificity in differentiating ChRCC from RO were 100% and 83.3%, respectively.

Conclusion

We propose MOC 31 and CD 82 as negative immunostains for RO, as these markers are commonly expressed in ChRCC. In conjunction with AMY1A strong immunopositivity in RO cases, we provide a triple panel of biomarkers (AMY1A, MOC 31, and CD 82) for the distinction between RO and ChRCC.

Clinical Implications of (Pro)renin Receptor (PRR) Expression in Renal Tumours

(1) Background: Renal cancer is one of the most frequent malignancies in Western countries, with an unpredictable clinical outcome, partly due to its high heterogeneity and the scarcity of reliable biomarkers of tumour progression. (Pro)renin receptor (PRR) is a novel receptor of the renin–angiotensin system (RAS) that has been associated with the development and progression of some solid tumours by RAS-dependent and -independent mechanisms. (2) Methods: In this study, we analysed the immunohistochemical expression of PRR at the centre and border in a series of 83 clear-cell renal cell (CCRCCs), 19 papillary (PRCC) and 7 chromophobe (ChRCC) renal cell carcinomas, and the benign tumour renal oncocytoma (RO, n = 11). (3) Results: PRR is expressed in all the tumour subtypes, with higher mean staining intensity in ChRCCs and ROs. A high expression of PRR at the tumour centre and at the infiltrative front of CCRCC tissues is significantly associated with high grade, tumour diameter, local invasion and stage, and with high mortality risk by UCLA integrated staging system (UISS) scale. (4) Conclusions: These findings indicate that PRR is associated with the development and progression of renal tumours. Its potential as a novel biomarker for RCC diagnosis/prognosis and as a promising therapeutic target should be taken into account in the future.

TSC/MTOR-mutated eosinophilic renal tumors are a distinct entity that is CK7+/CK20-/vimentin-: a validation study

Unclassified renal cell carcinoma (RCC) accounts for ∼10% of renal tumors, and the most common histologic finding in these cases is eosinophilic cytoplasm. We previously demonstrated that a subset of eosinophilic renal tumors with heterogeneous morphology and immunohistochemical (IHC) staining harbored pathogenic mutations in tuberous sclerosis complex (TSC) or mammalian target of rapamycin (MTOR) as the primary defining mutation. We identified an additional 8 cases of eosinophilic tumors with unusual morphology that were originally diagnosed as chromophobe RCC (CHRCC) or CHRCC, eosinophilic variant. As a comparison, we included four classic CHRCC cases and one CHRCC, eosinophilic variant case. Gross examination revealed solid or solid and cystic patterns. The solid areas were composed of eosinophilic tumor cells divided by congested vessels, whereas the cystic areas were lined by cytologically bland eosinophilic cells with septae containing nests, ribbons, and single eosinophilic tumor cells. The tumor cells had abundant granular eosinophilic cytoplasm with round nuclei and inconspicuous nucleoli. IHC analysis demonstrated diffuse staining for CK7 and negative staining for CK20 and vimentin. Next-generation sequencing identified pathogenic variants in three genes: TSC1, TSC2, and MTOR. They also lacked significant copy number variations in contrast to our control cases. We have demonstrated with our expanded study that cases previously diagnosed as CHRCC or CHRCC, eosinophilic variant with discordant histology and IHC staining patterns may represent a separate subtype of RCC characterized by mutations in the TSC/MTOR pathway.

Eosinophilic Renal Cell Tumors With a TSC and MTOR Gene Mutations Are Morphologically and Immunohistochemically Heterogenous: Clinicopathologic and Molecular Study

Eosinophilic renal neoplasms have a wide spectrum of histologic presentations, and several studies have demonstrated a subtype of renal cell carcinomas (RCCs) associated with the tuberous sclerosis complex (TSC)/mammalian target of rapamycin pathway. A review of our institutional archives led to the identification of 18 cases of renal eosinophilic tumors with unusual morphology. Immunohistochemical analysis demonstrated that these could be separated into 3 groups: group 1 had solid architecture and morphology similar to chromophobe RCC but was negative for CK20 and vimentin, and had weak focal staining for CK7 and P504S; group 2 had solid architecture and morphology similar to either renal oncocytoma or chromophobe RCC, eosinophilic variant and had diffuse staining of CK7 and P504S, absent to weak staining of CK20, and negative staining for vimentin; and group 3 had solid, cystic and papillary architecture and was negative for CK7, except for 1 case, along with moderate to strong staining of CK20, P504S, and vimentin. The cases were then sent for next-generation sequencing to determine whether molecular pathogenic variants were present. In group 1, all 3 cases had mutations in TSC2. In group 2, pathogenic variants were identified in 3 genes: TSC1, TSC2, and MTOR. In group 3, genetic alterations and pathogenic variants were identified in TSC1 and TSC2. Our results support TSC/MTOR-associated neoplasms as a distinct group that exhibits heterogenous morphology and immunohistochemical staining.

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.

Cytomorphology, immunoprofile, and management of renal oncocytic neoplasms

BACKGROUND

The goal of this study was to evaluate the morphology, immunoprofile, and management of renal oncocytoma (RO), hybrid oncocytic tumor (HOT), and chromophobe renal cell carcinoma (ChRCC).

METHODS

Forty-seven cases of RO, 7 cases of HOT, and 25 cases of ChRCC were included in the study. Tissue microarrays were prepared for immunohistochemical evaluation.

RESULTS

Large sheets of cells with transverse vessels, and higher nuclear grade were seen more often in ChRCC than in RO or HOT. Tumor cells of RO were more uniform in size and shape relative to HOT and ChRCC. The cytoplasmic features of RO were more uniformly granular relative to HOT and ChRCC, which exhibited variable cytoplasmic features. CK7 and MUC1 were expressed more frequently and diffusely in ChRCC (54% and 94%, respectively) than RO (4% and 52%, respectively) and HOT (0% and 71%, respectively). AMACR and PAX8 were more frequently expressed diffusely in RO (67% and 42%, respectively) than in HOT (0% and 0%, respectively) or ChRCC (14% and 11%, respectively). Most HOT (57%) and CHRCC (60%) patients underwent nephrectomy. Cryoablation was the treatment of choice for 24% of patients with ChRCC, 2% of patients with RO, and 0% of patients with HOT. The majority of patients with RO (88%) opted for active surveillance-a much higher rate than that for patients with HOT (29%) or ChRCC (12%).

CONCLUSION

Some cytologic features and immunomarkers are useful in differentiating RO, HOT, and ChRCC. Because no immunomarker or morphologic finding is specific by itself, a combination of morphologic features with immunohistochemistry appears to be the most reliable way to distinguish ChRCC, HOT, and RO on biopsy samples. Subclassification of renal oncocytic tumors into specific categories impacts clinical management and downstream treatment selection.

Decreased Mitochondrial DNA Content Drives OXPHOS Dysregulation in Chromophobe Renal Cell Carcinoma

Chromophobe renal cell carcinoma (chRCC) and renal oncocytoma are closely related, rare kidney tumors. Mutations in complex I (CI)-encoding genes play an important role in dysfunction of the oxidative phosphorylation (OXPHOS) system in renal oncocytoma, but are less frequently observed in chRCC. As such, the relevance of OXPHOS status and role of CI mutations in chRCC remain unknown. To address this issue, we performed proteome and metabolome profiling as well as mitochondrial whole-exome sequencing to detect mitochondrial alterations in chRCC tissue specimens. Multiomic analysis revealed downregulation of electron transport chain (ETC) components in chRCC that differed from the expression profile in renal oncocytoma. A decrease in mitochondrial (mt)DNA content, rather than CI mutations, was the main cause for reduced OXPHOS in chRCC. There was a negative correlation between protein and transcript levels of nuclear DNA- but not mtDNA-encoded ETC complex subunits in chRCC. In addition, the reactive oxygen species scavenger glutathione (GSH) was upregulated in chRCC due to decreased expression of proteins involved in GSH degradation. These results demonstrate that distinct mechanisms of OXPHOS exist in chRCC and renal oncocytoma and that expression levels of ETC complex subunits can serve as a diagnostic marker for this rare malignancy. SIGNIFICANCE: These findings establish potential diagnostic markers to distinguish malignant chRCC from its highly similar but benign counterpart, renal oncocytoma.

Sporadic oncocytic tumors with features intermediate between oncocytoma and chromophobe renal cell carcinoma: comprehensive clinicopathological and genomic profiling

Morphology, clinical behavior, and genomic profiles of renal oncocytoma (RO) and its malignant counterpart chromophobe renal cell carcinoma (ChRCC) are distinctly different. However, there is a substantial group of sporadic oncocytic tumors with peculiar hybrid phenotypes as well as a perplexing degree of morphologic and immunohistochemical overlap between classic RO and ChRCC with eosinophilic cytoplasm. The aim of this study is to provide detailed characterization of these hybrid tumors.Thirty-eight sporadic oncocytic neoplasms with ambiguous morphology from two institutions were reviewed by 4 pathologists. CKIT positivity was used as a selection criterion. We correlated CK7 and S100A1 immunostaining and detailed morphologic features with cytogenetic profiles. DNA from the formalin-fixed paraffin-embedded tissues was extracted and analyzed using cytogenomic microarray analysis (CMA) to evaluate copy number alterations (CNA) and ploidy. CMA categorized cases into 3 groups: RO (N = 21), RO variant (N = 7), and ChRCC (N = 10). Cytogenetic RO had either no CNA (48%) or loss of chromosome 1p, X, or Y (52%). RO variant had additional chromosomal losses [-9q, -14 (n = 2), -13] and chromosomal gains [+1q (n = 2), +4, +7 (n = 2), +13, +19, +20, and +22]. ChRCCs were either hypodiploid with numerous monosomies (40%) or hypotetraploid with multiple relative losses (60%). RO, RO variant, and ChRCC groups differed significantly in tumor architecture (p < 0.01), stroma (p = 0.013), presence of nuclear wrinkling, perinuclear halos, and well-defined cell borders in >5% of cells (p < 0.01), focal cell clearing (p = 0.048) and CK7 expression (p < 0.02). Pathologic prediction of the cytogenetic subtype using only two categories (benign RO or malignant ChRCC) would overcall or undercall up to 40% of tumors that were ChRCC based on cytogenetics. This finding provides the rationale for an intermediate diagnostic category of the so-called hybrid tumors (hybrid oncocytic/chromophobe tumor [HOCT]). HOCT was a heterogeneous group enriched for cytogenetic RO variant. Other HOCTs have a profile of either RO or ChRCC. The genomic profile allows classification of oncocytic tumors with ambiguous morphology into RO, RO variant, and ChRCC. Several architectural and cytologic features combined with CK7 expression are significantly associated with cytogenetic RO, RO variant, or ChRCC tumors. Doubled hypodiploidy by whole-genome endoduplication is a common phenomenon in eosinophilic ChRCC.

Diagnostic test accuracy of ADC values for identification of clear cell renal cell carcinoma: systematic review and meta-analysis

OBJECTIVES

To perform a systematic review on apparent diffusion coefficient (ADC) values of renal tumor subtypes and meta-analysis on the diagnostic performance of ADC for differentiation of localized clear cell renal cell carcinoma (ccRCC) from other renal tumor types.

METHODS

Medline, Embase, and the Cochrane Library databases were searched for studies published until May 1, 2019, that reported ADC values of renal tumors. Methodological quality was evaluated. For the meta-analysis on diagnostic test accuracy of ADC for differentiation of ccRCC from other renal lesions, we applied a bivariate random-effects model and compared two subgroups of ADC measurement with vs. without cystic and necrotic areas.

RESULTS

We included 48 studies (2588 lesions) in the systematic review and 13 studies (1126 lesions) in the meta-analysis. There was no significant difference in ADC of renal parenchyma using b values of 0-800 vs. 0-1000 (p = 0.08). ADC measured on selected portions (sADC) excluding cystic and necrotic areas differed significantly from whole-lesion ADC (wADC) (p = 0.002). Compared to ccRCC, minimal-fat angiomyolipoma, papillary RCC, and chromophobe RCC showed significantly lower sADC while oncocytoma exhibited higher sADC. Summary estimates of sensitivity and specificity to differentiate ccRCC from other tumors were 80% (95% CI, 0.76-0.88) and 78% (95% CI, 0.64-0.89), respectively, for sADC and 77% (95% CI, 0.59-0.90) and 77% (95% CI, 0.69-0.86) for wADC. sADC offered a higher area under the receiver operating characteristic curve than wADC (0.852 vs. 0.785, p = 0.02).

CONCLUSIONS

ADC values of kidney tumors that exclude cystic or necrotic areas more accurately differentiate ccRCC from other renal tumor types than whole-lesion ADC values.

KEY POINTS

• Selective ADC of renal tumors, excluding cystic and necrotic areas, provides better discriminatory ability than whole-lesion ADC to differentiate clear cell RCC from other renal lesions, with area under the receiver operating characteristic curve (AUC) of 0.852 vs. 0.785, respectively (p = 0.02). • Selective ADC of renal masses provides moderate sensitivity and specificity of 80% and 78%, respectively, for differentiation of clear cell renal cell carcinoma (RCC) from papillary RCC, chromophobe RCC, oncocytoma, and minimal-fat angiomyolipoma. • Selective ADC excluding cystic and necrotic areas are preferable to whole-lesion ADC as an additional tool to multiphasic MRI to differentiate clear cell RCC from other renal lesions whether the highest b value is 800 or 1000.

Comprehensive Immunoprofiles of Renal Cell Carcinoma Subtypes

In recent years, renal epithelial tumors have been among the fastest reclassifying tumors, requiring updates to the tumor classification system. Nonetheless, immunohistochemistry (IHC) remains the most widely used tool for renal epithelial tumors. In this proposal, we aimed to create the most efficient IHC panel for categorizing the diverse subtypes of renal tumors, and to find out more specific immunohistochemical results in each subtype or each antibody. A total of 214 renal tumors were analyzed using 10 possible IHC markers to differentiate subtypes, including three major renal cell carcinoma (RCC) subtypes, clear-cell type (50 cases), papillary type (50 cases), and chromophobe type (20 cases), and minor subtypes (MiT RCC, 13 cases; collecting duct carcinoma, 5 cases; and oncocytoma, 10 cases). A triple immunomarker (cytokeratin 7 (CK7)-carbonic anhydrase IX (CAIX)- alpha-methylacyl-CoA racemase (AMACR)) panel is useful in particular high-grade clear-cell tumors. If IHC remains ambiguous, the use of an adjunctive panel can be suggested, including CD10, epithelial membrane antigen, cathepsin K, c-kit, hepatocyte nuclear factor 1-β, and E-cadherin. For an efficient immunohistochemical strategy for subtyping of RCC, we conclude that the CK7-CAIX-AMACR panel is the best primary choice for screening subtyping.

Identification of Key Genes and Prognostic Analysis between Chromophobe Renal Cell Carcinoma and Renal Oncocytoma by Bioinformatic Analysis

The present techniques of clinical and histopathological diagnosis hardly distinguish chromophobe renal cell carcinoma (ChRCC) from renal oncocytoma (RO). To identify differentially expressed genes (DEGs) as effective biomarkers for diagnosis and prognosis of ChRCC and RO, three mRNA microarray datasets (GSE12090, GSE19982, and GSE8271) were downloaded from the GEO database. Functional enrichment analysis of DEGs was performed by DAVID. STRING and Cytoscape were applied to construct the protein-protein interaction (PPI) network and key modules of DEGs. Visualized plots were conducted by the R language. We downloaded clinical data from the TCGA database and the influence of key genes on the overall survival of ChRCC was performed by Kaplan–Meier and Cox analyses. Gene set enrichment analysis (GSEA) was utilized in exploring the function of key genes. A total of 79 DEGs were identified. Enrichment analyses revealed that the DEGs are closely related to tissue invasion and metastasis of cancer. Subsequently, 14 hub genes including ESRP1, AP1M2, CLDN4, and CLDN7 were detected. Kaplan–Meier analysis indicated that the low expression of CLDN7 and GNAS was related to the worse overall survival in patients with ChRCC. Univariate Cox analysis showed that CLDN7 might be a helpful biomarker for ChRCC prognosis. Subgroup analysis revealed that the expression of CLDN7 showed a downtrend with the development of the clinical stage, topography, and distant metastasis of ChRCC. GSEA analysis identified that cell adhesion molecules cams, B cell receptor signaling pathway, T cell receptor signaling pathway, RIG-I like receptor signaling pathway, Toll-like receptor signaling pathway, and apoptosis pathway were associated with the expression of CLDN7. In conclusion, ESRP1, AP1M2, CLDN4, PRSS8, and CLDN7 were found to distinguish ChRCC from RO. Besides, the low expression of CLDN7 was closely related to ChRCC progression and could serve as an independent risk factor for the overall survival in patients with ChRCC.

The Utility of ERBB4 and RB1 Immunohistochemistry in Distinguishing Chromophobe Renal Cell Carcinoma From Renal Oncocytoma

Objectives. Differentiating renal oncocytoma (RO) from chromophobe renal cell carcinoma (ChRCC) can occasionally be challenging. We evaluated the expression of RB1 and ERBB4 in RO and ChRCC, and compared the immunohistochemistry (IHC) results to RB1 and ERBB4 gene abnormalities detected by fluorescence in situ hybridization (FISH). Materials and Methods. Fifty-three kidney resections (ChRCC, n=28; RO, n=25) were stained for RB1 and ERBB4 IHC and FISH was performed to evaluate gene copy number analysis. Results. A loss of RB1 staining was identified in 64% (18/28) of ChRCCs, which was not found in any ROs (0/25; P <.001). FISH analysis revealed 36% (10/28) of ChRCCs contained a RB1 hemizygous deletion with a concordance of 56% (10/18) between the IHC and FISH findings. No RB1 gene copy number variations were detected in any of the ROs (0/25; P <.001) and retained expression of RB1 by IHC. ERBB4 showed cytoplasmic/membranous staining in all ROs and ChRCCs. However, 75% (21/28) of ChRCCs also contained nuclear positivity for ERBB4, which was uncommonly seen in ROs (3/25, 12%; P < .001). A hemizygous ERBB4 gene deletion was detected in 46% of ChRCCs (13/28), but none of the ROs (0/25; 0%). Loss of labeling by RB1 or nuclear staining for ERBB4 IHC identified 25 of 28 (89%) of ChRCCs. Conclusion. In summary, the loss of RB1 expression is a highly specific diagnostic biomarker in distinguishing ChRCC from RO. Nuclear ERBB4 expression also appears to be a sensitive diagnostic biomarker for ChRCC, albeit the mechanism is unknown.

Urinary Metabolomics Validates Metabolic Differentiation Between Renal Cell Carcinoma Stages and Reveals a Unique Metabolic Profile for Oncocytomas

Renal cell carcinoma (RCC) is a heterogeneous malignancy which often develops and progresses asymptomatically. Benign oncocytomas are morphologically similar to malignant chromophobe RCC and distinguishing between these two forms on cross-sectional imaging remains a challenge. Therefore, RCC-specific biomarkers are urgently required for accurate and non-invasive, pre-surgical diagnosis of benign lesions. We have previously shown that dysregulation in glycolytic and tricarboxylic acid cycle intermediates can distinguish benign lesions from RCC in a stage-specific manner. In this study, preoperative fasting urine samples from patients with renal masses were assessed by ¹H nuclear magnetic resonance (NMR). Significant alterations in levels of tricarboxylic acid cycle intermediates, carnitines and its derivatives were detected in RCC relative to benign masses and in oncocytomas vs. chromophobe RCC. Orthogonal Partial Least Square Discriminant Analysis plots confirmed stage discrimination between benign vs. pT1 (R2 = 0.42, Q2 = 0.27) and benign vs. pT3 (R2 = 0.48, Q2 = 0.32) and showed separation for oncocytomas vs. chromophobe RCC (R2 = 0.81, Q2 = 0.57) and oncocytomas vs. clear cell RCC (R2 = 0.32, Q2 = 0.20). This study validates our previously described metabolic profile distinguishing benign tumors from RCC and presents a novel metabolic signature for oncocytomas which may be exploited for diagnosis before cross-sectional imaging.

Utility of cytokeratin 7, S100A1 and caveolin-1 as immunohistochemical biomarkers to differentiate chromophobe renal cell carcinoma from renal oncocytoma

Background

Differentiation of chromophobe renal cell carcinoma (chRCC) from benign renal oncocytoma (RO) can be challenging especially when there are overlapping histological and morphological features. In this study we have investigated immunohistochemical biomarkers (cytokeratin 7/CK7, Caveolin-1/Cav-1 and S100 calcium-binding protein A1/S100A1) to aid in this difficult differentiation and attempted to validate their use in human renal tumour tissue to assess their discriminatory ability, particularly for chRCC and RO, in an Australian cohort of patients.

Methods

Retrospective study was carried out of archived formalin-fixed paraffin-embedded renal tumours from tumour nephrectomy specimens of 75 patients: 30 chRCC, 15 RO and 30 clear cell RCC (ccRCC). Sections were cut and immunostained with specific polyclonal antibodies of CK7, Cav-1 and S100A1. Morphometry was used to determine expression patterns of the biomarkers using Aperio ImageScope. Results were assessed with student t-test and ANOVA with significance at P<0.05.

Results

From this cohort, male-to-female ratio was 1.9:1. Median age was 64 (45-88 years) and median tumour size was 3.8 cm (range, 1.2-18 cm). There were 47 (62.7%) T1, 7 T2, 20 T3 and one T4 stage of RCC; with 2 patients presenting with M1 stage. There was significantly higher CK7 expression in chRCC compared to RO (P=0.03), and chRCC also had a different staining pattern and higher expression of Cav-1 compared to RO. There was higher expression of S100A1 in RO compared to chRCC.

Conclusions

Immunohistochemical staining and standard morphometry of CK7, Cav-1 and S100A1 can aid in the differentiation of chRCC and RO. This may guide clinicians in management of patients when faced with difficult diagnostic histological distinction between the two tumour subtypes.

Proteomic distinction of renal oncocytomas and chromophobe renal cell carcinomas

BACKGROUND

Renal oncocytomas (ROs) are benign epithelial tumors of the kidney whereas chromophobe renal cell carcinoma (chRCCs) are malignant renal tumors. The latter constitute 5-7% of renal neoplasias. ROs and chRCCs show pronounced molecular and histological similarities, which renders their differentiation demanding. We aimed for the differential proteome profiling of ROs and early-stage chRCCs in order to better understand distinguishing protein patterns.

METHODS

We employed formalin-fixed, paraffin-embedded samples (six RO cases, six chRCC cases) together with isotopic triplex dimethylation and a pooled reference standard to enable cohort-wide quantitative comparison. For lysosomal-associated membrane protein 1 (LAMP1) and integrin alpha-V (ITGAV) we performed corroborative immunohistochemistry (IHC) in an extended cohort of 42 RO cases and 31 chRCC cases.

RESULTS

At 1% false discovery rate, we identified > 3900 proteins, of which > 2400 proteins were consistently quantified in at least four RO and four chRCC cases. The proteomic expression profiling discriminated ROs and chRCCs and highlighted established features such as accumulation of mitochondrial proteins in ROs together with emphasizing the accumulation of endo-lysosomal proteins in chRCCs. In line with the proteomic data, IHC showed enrichment of LAMP1 in chRCC and of ITGAV in RO.

CONCLUSION

We present one of the first differential proteome profiling studies on ROs and chRCCs and highlight differential abundance of LAMP1 and ITGAV in these renal tumors.

Modern Pathologic Diagnosis of Renal Oncocytoma

Oncocytoma is a well-defined benign renal tumor, with classic gross and histologic features, including a tan or mahogany-colored mass with central scar, microscopic nested architecture, bland cytology, and round, regular nuclei with prominent central nucleoli. As a result of variations in this classic appearance, difficulty in standardizing diagnostic criteria, and entities that mimic oncocytoma, such as eosinophilic variant chromophobe renal cell carcinoma and succinate dehydrogenase-deficient renal cell carcinoma, pathologic diagnosis remains a challenge. This review addresses the current state of pathologic diagnosis of oncocytoma, with emphasis on modern diagnostic markers, areas of controversy, and emerging techniques for less invasive diagnosis, including renal mass biopsy and advanced imaging.

Renal cell carcinoma: the search for a reliable biomarker

One particular challenge in the treatment of kidney tumors is the range of histologies and tumor phenotypes a renal mass can represent. A kidney tumor can range from benign (e.g., oncocytoma) to a clinically indolent malignancy (e.g., papillary type I, chromophobe) to aggressive disease [e.g., papillary type II or high-grade clear cell renal cell carcinoma (ccRCC)]. Even among various subtypes, kidney cancers are genetically diverse with variable prognoses and treatment response rates. Therefore, the key to proper treatment is the differentiation of these subtypes. Currently, a wide array of diagnostic, prognostic, and predictive biomarkers exist that may help guide the individualized care of kidney cancer patients. This review will discuss the various serum, urine, imaging, and immunohistological biomarkers available in practice.

Pax8, Napsin A, and CD10 as Immunohistochemical Markers of Canine Renal Cell Carcinoma

Pax8, napsin A, and CD10 are useful immunohistochemical markers of human renal cell carcinoma (RCC); however, their diagnostic utility in canine RCC is unclear. Forty formalin-fixed paraffin-embedded renal cell carcinomas from dogs (15 papillary, 12 solid, and 13 tubular) and 10 metastases were evaluated for expression of Pax8, napsin A, and CD10. Thirty-nine (98%), 24 (60%), and 19 (50%) tumors expressed Pax8 (nuclear labeling), napsin A (cytoplasmic labeling), and CD10 (cytoplasmic and membranous labeling), respectively. Pax8 was expressed in 92% of solid, 100% of papillary, and 100% of tubular tumors. Napsin A was expressed in 58% of solid, 60% of papillary, and 62% of tubular RCC. CD10 was expressed in 33% of solid, 47% of papillary, and 62% of tubular RCC. Pax8 was expressed in 80% of the metastatic tumors, napsin A in 60%, and CD10 in 50%. Additionally, Pax8 immunoreactivity was stronger overall than that of napsin A or CD10. In summary, Pax8 is a more sensitive marker than napsin A or CD10 for primary and metastatic canine RCC; its nuclear and more intense reactivity also makes it easier to interpret. Tubular and papillary RCCs were more likely than solid RCC to express all 3 markers. These findings highlight the utility of Pax8 as an immunohistochemical marker in diagnosing all major subtypes of canine primary and metastatic renal cell carcinoma.

High expression of Aldolase A predicts poor survival in patients with clear-cell renal cell carcinoma

Background

Aldolase A (ALDOA) is a glycolytic enzyme that drives the glycolytic metabolic pathway in mammalian cells. The overexpression of ALDOA was observed in a variety of cancers including clear-cell renal cell carcinoma (ccRCC). However, little was known about the clinicopathological significance and prognostic value of ALDOA in ccRCC patients.

Methods

The expression of ALDOA was detected using immunohistochemical staining in 162 formalin-fixed, paraffin-embedded ccRCC sections. Prognostic outcomes correlated with ALDOA were examined using Kaplan–Meier analysis and the Cox proportional hazards model.

Results

In patients with ccRCC, increased cytoplasmic ALDOA expression was positively associated with tumor size (P=0.021), TNM stages (P=0.034), lymph node metastasis (P=0.020), and overall survival (OS) (P<0.001). Kaplan–Meier analysis showed that high cytoplasmic expression of ALDOA was associated with a statistically significant lower OS (P<0.001). Multivariate analysis demonstrated that ALDOA expression was an independent and significant prognostic factor (HR =3.561, 95% CI =1.715–7.396, P=0.001). ALDOA expression was not associated with significant prognostic deference in the subgroups of TNM stage I patients or pT1 patients.

Conclusion

Our results suggest that ALDOA expression is an independent prognostic factor for OS in patients with ccRCC.

Correlating Preoperative Imaging with Histologic Subtypes of Renal Cell Carcinoma and Common Mimickers

Renal cell carcinoma (RCC) consists of distinct subtypes that have unique pathologic and imaging features as well as specific cytogenetic and molecular characteristics. As the prognosis and therapeutic strategies may differ for each subtype, correlation of the preoperative imaging with the pathologic findings is of great clinical relevance. In addition, differentiation of RCC from benign entities is ideal in order to prevent overtreatment. However, a noninvasive diagnosis with imaging alone is not always straightforward due to the overlapping appearance of RCC with benign lesions such as fat-poor angiomyolipoma and oncocytoma. With new imaging modalities, there have been significant improvements in correlating preoperative imaging with pathologic characteristics. These new discoveries are able to aid in a more specific, noninvasive, diagnosis that in turn helps direct patient management.

Is Multiparametric MRI Useful for Differentiating Oncocytomas From Chromophobe Renal Cell Carcinomas?

OBJECTIVE

The purpose of this study was to retrospectively evaluate the diagnostic accuracy of multiparametric MRI to differentiate oncocytoma from chromophobe renal cell carcinoma (RCC).

MATERIALS AND METHODS

In this retrospective study, 26 histologically confirmed oncocytomas and 16 chromophobe RCCs that underwent full MRI examination were identified in 42 patients (25 men and 17 women) over a 6-year period. Demographic data were recorded. Double-echo chemical-shift, dynamic contrast-enhanced T1- and T2-weighted images, and apparent diffusion coefficient (ADC) maps were reviewed independently by two radiologists blinded to pathologic results. Signal-intensity index (SII), tumor-to-spleen signal-intensity ratio, ADC ratio, three wash-in indexes, and two washout indexes were calculated and compared using univariate and ROC analyses. Sensitivity and specificity analyses were performed to calculate diagnostic accuracy.

RESULTS

All carcinomas and nine oncocytomas were resected; the remaining 17 oncocytomas were biopsied. Patient age (for oncocytomas: mean, 68.2 years; range, 43-84 years; for RCCs: mean, 60.8 years; range, 20-79 years) and tumor size (for oncocytomas: mean, 35.5 mm; range, 12-98 mm; for RCCs: mean, 37.2 mm; range, 9-101 mm) did not differ significantly across groups (p = 0.132 and 0.265, respectively). Good interobserver agreement was observed for all measurements but four. Oncocytomas presented significantly higher ADC (p = 0.002) and faster enhancement (p = 0.007-0.012) but lower SII (p = 0.03) than carcinomas. This combination provided sensitivity of 92.3% (24/26), specificity of 93.8% (15/16), and accuracy of 92.9% (39/42) for the detection of oncocytomas.

CONCLUSION

Multiparametric MRI helps to accurately differentiate oncocytomas from chromophobe RCCs with high sensitivity and specificity.

Caveolin-1 in the regulation of cell metabolism: a cancer perspective

Caveolin-1 (CAV1) is an oncogenic membrane protein associated with endocytosis, extracellular matrix organisation, cholesterol distribution, cell migration and signaling. Recent studies reveal that CAV1 is involved in metabolic alterations – a critical strategy adopted by cancer cells to their survival advantage. Consequently, research findings suggest that CAV1, which is altered in several cancer types, influences tumour development or progression by controlling metabolism. Understanding the molecular interplay between CAV1 and metabolism could help uncover druggable metabolic targets or pathways of clinical relevance in cancer therapy. Here we review from a cancer perspective, the findings that CAV1 modulates cell metabolism with a focus on glycolysis, mitochondrial bioenergetics, glutaminolysis, fatty acid metabolism, and autophagy.