Application of molecular diagnostic techniques to renal epithelial neoplasms

Review of renal cell carcinoma and its common subtypes in radiology

Representing 2%-3% of adult cancers, renal cell carcinoma (RCC) accounts for 90% of renal malignancies and is the most lethal neoplasm of the urologic system. Over the last 65 years, the incidence of RCC has increased at a rate of 2% per year. The increased incidence is at least partly due to improved tumor detection secondary to greater availability of high-resolution cross-sectional imaging modalities over the last few decades. Most RCCs are asymptomatic at discovery and are detected as unexpected findings on imaging performed for unrelated clinical indications. The 2004 World Health Organization Classification of adult renal tumors stratifies RCC into several distinct histologic subtypes of which clear cell, papillary and chromophobe tumors account for 70%, 10%-15%, and 5%, respectively. Knowledge of the RCC subtype is important because the various subtypes are associated with different biologic behavior, prognosis and treatment options. Furthermore, the common RCC subtypes can often be discriminated non-invasively based on gross morphologic imaging appearances, signal intensity on T2-weighted magnetic resonance images, and the degree of tumor enhancement on dynamic contrast-enhanced computed tomography or magnetic resonance imaging examinations. In this article, we review the incidence and survival data, risk factors, clinical and biochemical findings, imaging findings, staging, differential diagnosis, management options and post-treatment follow-up of RCC, with attention focused on the common subtypes.

IMA901: a multi-peptide cancer vaccine for treatment of renal cell cancer

Despite a major improvement in the treatment of advanced kidney cancer by the recent introduction of targeted agents such as multi-kinase inhibitors, long-term benefits are still limited and a significant unmet medical need remains for this disease. Cancer immunotherapy has shown its potential by the induction of long-lasting responses in a small subset of patients, however, the unspecific immune interventions with (high dose) cytokines used so far are associated with significant side effects. Specific cancer immunotherapy may circumvent these problems by attacking tumor cells while sparing normal tissue with the use of multi-peptide vaccination being one of the most promising strategies. We here summarize the clinical and translational data from phase I and II trials investigating IMA901. Significant associations of clinical benefit with detectable T cell responses against the IMA901 peptides and encouraging survival data in treated patients has prompted the start of a randomized, controlled phase III trial in 1st line advanced RCC with survival results expected toward the end of 2015. Potential combination strategies with the recently discovered so-called checkpoint inhibitors are also discussed.

Significance of chromosome 9p status in renal cell carcinoma: a systematic review and quality of the reported studies

Defining the prognosis of renal cell carcinoma (RCC) using genetic tests is an evolving area. The prognostic significance of 9p status in RCC, although described in the literature, remains underutilised in clinical practice. The study explored the causes of this translational gap. A systematic review on the significance of 9p status in RCC was performed to assess its clinical applicability and impact on clinical decision-making. Medline, Embase, and other electronic searches were made for studies reporting on 9p status in RCC. We collected data on: genetic techniques, pathological parameters, clinical outcomes, and completeness of follow-up assessment. Eleven studies reporting on 1,431 patients using different genetic techniques were included. The most commonly used genetic technique for the assessment of 9p status in RCC was fluorescence in situ hybridization. Combined genomic hybridisation (CGH), microsatellite analysis, karyotyping, and sequencing were other reported techniques. Various thresholds and cut-off values were used for the diagnosis of 9p deletion in different studies. Standardization, interobserver agreement, and consensus on the interpretation of test remained poor. The studies lacked validation and had high risk of bias and poor clinical applicability as assessed by two independent reviewers using a modified quality assessment tool. Further protocol driven studies with standardised methodology including use of appropriate positive and negative controls, assessment of interobserver variations, and evidenced based follow-up protocols are needed to clarify the role of 9p status in predicting oncological outcomes in renal cell cancer.

An investigation of risk factors for renal cell carcinoma by histologic subtype in two case-control studies

To investigate whether renal cell carcinoma (RCC) histologic subtypes possess different etiologies, we conducted analyses of established RCC risk factors by subtype (clear cell, papillary and chromophobe) in two case-control studies conducted in the United States (1,217 cases, 1,235 controls) and Europe (1,097 cases, 1,476 controls). Histology was ascertained for 706 U.S. cases (58% of total) and 917 European cases (84%) through a central slide review conducted by a single pathologist. For the remaining cases, histology was abstracted from the original diagnostic pathology report. Case-only analyses were performed to compute odds ratios (ORs) and 95% confidence intervals (CI) summarizing subtype differences by age, sex and race. Case-control analyses were performed to compute subtype-specific ORs for other risk factors using polytomous regression. In case-only analyses, papillary cases (N = 237) were older (OR = 1.2, 95% CI = 1.1-1.4 per 10-year increase), less likely to be female (OR = 0.5, 95% CI = 0.4-0.8) and more likely to be black (OR = 2.6, 95% CI = 1.8-3.9) as compared to clear cell cases (N = 1,524). In case-control analyses, BMI was associated with clear cell (OR = 1.2, 95% CI = 1.1-1.3 per 5 kg/m(2) increase) and chromophobe RCC (N = 80; OR = 1.2, 95% CI = 1.1-1.4), but not papillary RCC (OR = 1.1, 95% CI = 1.0-1.2; test versus clear cell, p = 0.006). No subtype differences were observed for associations with smoking, hypertension or family history of kidney cancer. Our findings support the existence of distinct age, sex and racial distributions for RCC subtypes, and suggest that the obesity-RCC association differs by histology.

Laser-assisted microdissection in translational research: theory, technical considerations, and future applications

Molecular profiling already exerts a profound influence on biomedical research and disease management. Microdissection technologies contribute to the molecular profiling of diseases, enabling investigators to probe genetic characteristics and dissect functional physiology within specific cell populations. Laser-capture microdissection (LCM), in particular, permits collation of genetic, epigenetic, and gene expression differences between normal, premalignant, and malignant cell populations. Its selectivity for specific cell populations promises to greatly improve the diagnosis and management of many human diseases. LCM has been extensively used in cancer research, contributing to the understanding of tumor biology by mutation detection, clonality analysis, epigenetic alteration assessment, gene expression profiling, proteomics, and metabolomics. In this review, we focus on LCM applications for DNA, RNA, and protein analysis in specific cell types and on commercially available LCM platforms. These analyses could clinically be used as aids to cancer diagnosis, clinical management, genomic profile studies, and targeted therapy. In this review, we also discuss the technical details of tissue preparation, analytical yields, tissue selection, and selected applications using LCM.

Multilocular cystic renal cell carcinoma: similarities and differences in immunoprofile compared with clear cell renal cell carcinoma

Multilocular cystic renal cell carcinoma (RCC) is an uncommon renal neoplasm composed of thin fibrous septa lining multiple cystic spaces and associated with an excellent prognosis. Clear cells with generally low-grade nuclear features line the cystic spaces and may be present within the fibrous septa, although solid mass-forming areas are by definition absent. Despite the excellent prognosis, molecular-genetic alterations are similar to those of clear cell RCC. Immunohistochemical staining characteristics, however, have not been well elucidated. We studied 24 cases of multilocular cystic RCC, classified according to the 2004 World Health Organization System. Immunohistochemical analysis was performed using an automated immunostainer for CD10, cytokeratin 7 (CK7), α-methylacyl-CoA-racemase, epithelial membrane antigen (EMA), cytokeratin CAM 5.2, carbonic anhydrase IX (CA-IX), estrogen/progesterone receptors, smooth muscle actin, PAX-2, and vimentin. Twenty-four cases of grade 1 to 2 clear cell RCC were stained for comparison. Multilocular cystic RCC and control cases of clear cell RCC showed the following results, respectively: CD10 (63%, 96%), CK7 (92%, 38%), α-methylacyl-CoA-racemase (21%, 67%), vimentin (58%, 33%), estrogen receptor (8%, 8%), CAM 5.2 (100%, 96%), EMA, CA-IX, PAX-2 (all 100%), and progesterone receptor (0%). Smooth muscle actin highlighted myofibroblastic cells within the septa of multilocular cystic RCC and the fine capillary vascular network of clear cell RCC. In summary, multilocular cystic RCC showed expression of common clear cell RCC markers CA-IX, EMA, and PAX-2, supporting the hypothesis that multilocular cystic RCC is a subtype of clear cell RCC. In contrast to clear cell RCC, tumors less frequently expressed CD10 (63% and often focal vs. 96% and diffuse) and more frequently expressed CK7 (92%), often diffusely (63%). Coexpression of CA-IX and CK7 represents a point of overlap with the recently described clear cell papillary RCC, which also may show a prominent cystic architecture. However, the latter lacks mutation of the VHL gene and deletion of chromosome 3p by molecular methodologies.

Regulatory Effects of microRNA-92 (miR-92) on VHL Gene Expression and the Hypoxic Activation of miR-210 in Clear Cell Renal Cell Carcinoma

Background & Aims: In order to understand the role of miRNAs in renal tumorigenesis, we undertook a stepwise approach that included a comprehensive differential miRNA expression analysis for the most common histological subtypes of human renal neoplasms appearing in either sporadic or hereditary forms. We also aimed to test the hypothesis that microRNAs can act as an alternative mechanism of VHL gene inactivation and therefore might be correlated with tumorigenesis in ccRCC. Finally, we wanted to explore whether the well-known hypoxic activation of ccRCC is followed by a specific pattern of miRNA expression.

Methods: Tumor and normal adjacent kidney parenchyma from patients with RCC were tested for microRNA expression. Twenty cases of different histologies were used for profiling by PCR miRNA arrays. For validation, a separate cohort of samples used to test specifically miR92a expression and its involvement in VHL gene mRNA silencing. Finally, miR210 as a marker of hypoxia was evaluated. Expression values were correlated with important clinicopathologic features from the patients.

Results: We identified unique miRNA expression signatures for each histologic subtype of kidney tumors. Expression values for downregulated miRNAs ranged from 0.3-fold (in VHL-clear cell RCC) up to 0.393 fold (in papillary type II (HLRCC) tumors). For the upregulated miRNAs, fold-changes ranged from 2.1 up to 290-fold. Specific patterns together with type-specific profiles were observed. Twenty-three miRNAs were found to be differentially expressed in both sporadic and VHL-dependent ccRCC. Sporadic clear cell tumors showed a unique pattern of 14-miRNA that were absent from the VHL-dependent tumors. These also showed 15 miRNAs specific to the hereditary type. Common miRNAs to both sporadic and hereditary forms included miR-92a and miR-210. For miR-92a, and a striking inverse correlation with VHL mRNA levels was found. For the hypoxia-regulated miR-210, clear cell tumors showed significantly higher expression levels when compared to tumor of non-clear cell histology (9.90-fold vs. 1.36, p<0.001).

Conclusions: microRNA expression seems to be involved in every step of RCC pathogenesis: both as an element for tumor development as well as a consequence of or in response to the initial malignant transformation and part of tumor progression. Our data show consistent disregulation of miRNAs in human kidney cancer, some of which are potentially involved in critical gene silencing in RCC and others that are activated as part of the pathophysiological response in these tumors.

Clinical genomics of renal epithelial tumors

Kidney and upper urinary tract cancers account for approximately 54,000 cases every year in the United States, and represent about 3.7% of adult malignancies, with more than 13,000 annual deaths. Classification of renal tumors is typically based on histomorphologic characteristics but, on occasion, morphologic characteristics are not sufficient. Each of the most common histologic subtypes harbors specific recurrent genetic abnormalities, such as deletion of 3p in conventional clear cell carcinoma, trisomy 7 and 17 in papillary renal cell carcinoma, multiple monosomies in chromophobe renal cell carcinoma, and a nearly diploid genome in benign oncocytomas. Knowledge of this information can provide diagnostic support and prognostic refinement in renal epithelial tumors. Identification of the specific subtype of a renal tumor is critical in guiding surveillance for recurrence and the appropriate use of targeted therapies. Cytogenomic arrays are increasingly being used as a clinical tool for genome-wide assessment of copy number and loss of heterozygosity in renal tumors. In addition, the improved understanding of the hereditary causes of renal tumors and their role in sporadic malignancies has led to the development of more effective targeted therapies. This review summarizes the genetic and genomic changes in the most common types of renal epithelial tumors and highlights the clinical implications of these aberrations.

Multilocular cystic renal cell carcinoma is a subtype of clear cell renal cell carcinoma

Multilocular cystic renal cell carcinoma is an uncommon low grade renal cell carcinoma with unique morphologic features. Its cytogenetic characteristics have not been fully investigated. Its relationship to typical clear cell renal cell carcinoma is uncertain. We evaluated 19 cases of multilocular cystic renal cell carcinoma diagnosed by strict morphologic criteria using the 2004 WHO classification system. The control group consisted of 19 low grade (Fuhrman grades 1 or 2) clear cell renal cell carcinomas. Chromosome 3p deletion status was determined by dual color interphase fluorescence in situ hybridization analysis. Chromosome 3p deletion was identified in 17 out of 19 (89%) of the clear cell renal cell carcinoma cases and 14 out of 19 (74%) of the multilocular cystic renal cell carcinoma cases, respectively. There was no difference in the status of chromosome 3p deletion between clear cell renal cell carcinoma and multilocular cystic renal cell carcinoma (P=0.40). These results support the concept that multilocular cystic renal cell carcinoma as a subtype of clear cell renal cell carcinoma.

Diagnostic usefulness of fluorescent cytogenetics in differentiating chromophobe renal cell carcinoma from renal oncocytoma: a validation study combining metaphase and interphase analyses

We investigated the usefulness of interphase fluorescence in situ hybridization (FISH) analysis to differentiate between 11 chromophobe renal carcinomas and 12 renal oncocytomas, showing different clinical outcomes, when compared with conventional metaphase cytogenetics by karyotyping. Karyotypically, 3 chromophobe renal cell carcinomas showed losses of chromosomes, 3 were polyploid, 1 was normal, and 4 failed to grow. Of 12 oncocytomas, 5 showed a normal numeric karyotype and 6 additional structural rearrangements. FISH on chromophobe renal cell carcinomas showed a high percentage of cases (10/11 [91%]) with multiple numeric losses among chromosomes 1, 2, 6, 10, and 17; this interphase pattern was observed irrespective of the 3 different metaphase karyotypes. Of 12 oncocytomas, 11 (92%) revealed a normal numeric chromosomal status showing at least 2 chromosomes without aneusomy by interphase FISH. The study demonstrates that indeed FISH performed on formalin-fixed, paraffin-embedded tissue can provide clinically useful information more reliably than karyotyping of most of these tumors.

Chromophobe renal cell cancer--review of the literature and potential methods of treating metastatic disease

Chromophobe renal cell carcinoma (ChRCC) is a subtype of renal cell carcinoma (RCC). ChRCC is diagnosed mainly in 6th decade of life. An incidence of ChRCC is similar in both men and woman. Eighty six percent of ChRCCs cases are diagnosed in stage 1 or 2. Prognosis of ChRCC is better than in other types of RCC. Five- and 10-year disease free survival (DFS) for ChRCC was 83.9% and 77.9%, respectively. Expression of immunohistological markers: cytokeratins (CK), vimentin, epithelial membrane antigen (EMA), CD10 could be potentially helpful in diagnosis of different subtypes of RCC. From all conventional RCC, CD 117 was detected (overexpression) in membrane of cells ChRCC.Overexpression of CD117 on cellular membranes of ChRCC could be a potential target for kinase inhibitors like: imatinib, dasatinib, nilotinib. The potential targets for other kinase inhibitors (sunitinib and sorafenib) in ChRCC seem to be VEGFR and PDGFR. On the basis for formulating research hypotheses which should be verified by prospective studies.

Adult cystic nephroma and mixed epithelial and stromal tumor of the kidney are the same disease entity: molecular and histologic evidence

Adult cystic nephroma (CN) and mixed epithelial and stromal tumor of the kidney (MEST) are considered as separate entities in the 2004 World Health Organization classification of renal neoplasms. Recent studies suggested that the two share clinicopathologic features and may represent the same disease process of varying morphology. However, definitive genetic evidence is lacking. We examined their relationship using gene expression profiling and histologic analysis. Gene expression profiles of 3 CN and 3 MEST were analyzed using HGU133 Plus 2.0 microarrays (Affymetrix) and were compared with each other and also with 48 other renal tumors and 13 normal kidneys. Histologic examination of 26 CN and 13 MEST focused on the cystic septal thickness, cyst-to-stroma ratio, stromal cellularity and composition, types of epithelial cells lining cysts and glands, and estrogen and progesterone receptors expression. Patients' age, sex distribution, and tumor size were similar between the two. They also shared many histologic features, including lining epithelium of cysts and glands, stromal cellularity and composition. Unsupervised clustering of mRNA expression profiles demonstrated that they had very similar expression profiles that were distinct from other renal tumors. By microarray analysis, progesterone receptor expression was significantly higher in CN and MEST relative to both normal and other renal tumors, while estrogen receptor expression was not. By immunohistochemistry, expression of both receptors was similar between CN and MEST. This study provides the most convincing molecular evidence that CN and MEST represent different parts of the morphologic spectrum of the same disease.

Molecular and cytogenetic insights into the pathogenesis, classification, differential diagnosis, and prognosis of renal epithelial neoplasms

Renal cell carcinomas comprise a heterogeneous group of epithelial neoplasms with diverse biologic potential and variable clinical outcomes. The application of molecular and cytogenetic techniques to the study of renal neoplasms has improved our understanding of the molecular mechanisms responsible for tumor initiation and progression. Molecular classification of renal cell carcinomas has also provided new avenues for diagnosis, clinical outcome, and therapy response prediction. In this article, we review the molecular markers for various renal epithelial neoplasms and discuss the mechanisms underlying the development of these neoplasms. We also evaluate the use of molecular and cytogenetic techniques in establishing an accurate diagnosis in difficult cases and their potential usefulness in accurately classifying renal neoplasms, assessing prognosis, and selecting appropriate therapy.

Molecular diagnosis of renal cell neoplasms: the usefulness of immunohistochemistry and fluorescence in situ hybridization

BACKGROUND

The classification of renal cell neoplasms includes different subtypes of tumors characterized by different outcome. Some overlapping morphological features and the increasing recognition of new entities are making the traditional histologic distinction of renal cell neoplasms difficult and more tools improving the specificity of the correct identification are needed. Among molecular analyses, immunohistochemistry and fluorescence in situ hybridization have become the most helpful procedures, solving many issues in the differential diagnosis of the renal cell neoplasms.

OBJECTIVE

The aim of this review is to merge the large amount of recent knowledge regarding molecular markers of renal cell neoplasms into a helpful diagnostic algorithm.

CONCLUSION

It is proposed that immunoreactions for CD10, Alpha-methylacyl-CoA racemase, cytokeratin 7, parvalbumin and S100A1, and the cytogenetical analysis of chromosomes 3p, 1, 2, 6, 7, 10, 17 and Y can now offer the most specific tools for the classification of renal cell tumors.

Benign renal neoplasms in adults: cross-sectional imaging findings

OBJECTIVE

A broad spectrum of benign renal neoplasms in adults shows characteristic ontogeny, histology, and tumor biology. Benign renal tumors are classified into renal cell tumors, metanephric tumors, mesenchymal tumors, and mixed epithelial and mesenchymal tumors. Select benign tumors show characteristic anatomic distribution and imaging features. However, because of overlapping of findings between benign and malignant renal tumors, histologic evaluation may be required to establish a definitive diagnosis. Accurate preoperative characterization facilitates optimal patient management.

CONCLUSION

We attempt to provide a comprehensive, contemporary review of benign renal neoplasms that occur in adults, focusing on cross-sectional imaging characteristics.

Loss of chromosome 9p is an independent prognostic factor in patients with clear cell renal cell carcinoma

Loss of chromosome 9p has been implicated in the progression of renal cell carcinoma. We evaluated the clinical utility of fluorescence in situ hybridization analysis of loss of chromosome 9p in 73 patients with clear cell renal cell carcinomas with varied stage, size, grade, necrosis (SSIGN) scores. Loss of chromosome 9p was observed in 13 tumors (18%). The 5-year cancer-specific survival of patients without loss of chromosome 9p was 88% and was 43% in those with loss of chromosome 9p (P<0.001). Local extension of the primary tumor according to the 2002 TNM staging system, lymph node involvement, the presence of distant metastases, and the SSIGN score were the other variables that predicted cancer-specific survival in univariate analysis. Loss of chromosome 9p was an independent prognostic factor in multivariate analysis. Our data indicate that the detection of chromosome 9p loss by fluorescence in situ hybridization analysis of clear cell renal cell carcinoma adds prognostic information beyond the pathological factors included in the current predictive models for renal cell carcinoma, such as SSIGN score.

Segmental disorders of the nephron: histopathological and imaging perspective

Recent advances in molecular genetics and immunocytochemistry have clarified the cell of origin in many renal disorders. Several renal disorders are thought to involve specific segments of the nephron. Renin-secreting tumours arise from juxtaglomerular cells. Clear cell and papillary renal cell carcinoma (RCC) recapitulate the epithelium of the proximal tubules. Oncocytoma and chromophobe RCC differentiate towards Type A and Type B intercalated cells of the cortical collecting duct, respectively. Medullary collecting ducts are the target sites for the development of autosomal recessive polycystic kidney disease, collecting duct carcinoma and medullary carcinoma. Renal papillae are susceptible to unique changes such as necrosis or papillitis. The purpose of our article is threefold: to illustrate the imaging findings of renal disorders that show segmental involvement of the nephron, to describe proximal and distal nephron disorders and to correlate imaging findings of some entities with histopathological features.

Update on radiological imaging of renal cell carcinoma

US is frequently used as the initial imaging in patients with suspected renal disease. US contrast agents offer the potential to increase the sensitivity in patients who cannot undergo CT or MTI. Harmonic imaging has helped with the evaluation of renal cystic lesions. CT remains the reference standard for staging and lesion characterization. The rapid technological advances mean that ultra-thin slices and 3D imaging have now become more widely available. MRI has also greatly advanced in speed and image quality, but at present, imaging time and scanner availability mean that MRI is generally used as a problem-solving tool. It is particularly helpful for smaller lesions and complex cystic lesions, where subtraction can be used to accurately identify the presence of enhancement. MRI is used as the primary diagnostic tool for patients with radiation concerns and those with renal failure. Caution must now also be taken in these patients, given the recent studies raising the association of gadolinium-based compounds and NSF. There have been dramatic improvements in renal imaging over the last decade, offering better resolution, shorter imaging times and better patient acceptance. The progress in minimally invasive techniques has driven the need to provide better preoperative information to the surgeon. The future of renal imaging is an exciting field; perhaps with fluorodeoxyglucose-based positron emission tomography we will be able to predict the biological behaviour of a tumour, and molecular imaging agents will become available to identify and hopefully treat specific tumour types.

Chromosomal gains in the sarcomatoid transformation of chromophobe renal cell carcinoma

The hallmark of chromophobe renal cell carcinoma is multiple chromosomal losses from among chromosomes 1, 2, 6, 10 and 17. Chromophobe renal cell carcinoma with distant metastases or sarcomatoid transformation are uncommon and little is known about their chromosomal abnormalities. We collected six sarcomatoid chromophobe renal cell carcinomas and three primary chromophobe renal cell carcinomas with distant metastases. A cytogenetic analysis by fluorescent in situ hybridization on paraffin-embedded tissue was performed using centromeric probes for chromosomes 1, 2, 6, 10 and 17. We found more than one signal in four of six (66%) sarcomatoid chromophobe renal cell carcinomas, in both sarcomatoid and adjacent epithelial components. Both primary chromophobe renal cell carcinomas and matched metastases showed single signals for all chromosomes studied in two cases and no abnormalities in the remaining case. We concluded that: (1) both epithelial and sarcomatoid components of sarcomatoid chromophobe renal cell carcinoma show different genetic abnormalities from those characteristic of chromophobe renal cell carcinoma; (2) sarcomatoid chromophobe renal cell carcinomas frequently have multiple gains (polysomy) of chromosomes 1, 2, 6, 10 and 17; (3) distant metastases show the same genetic patterns, usually chromosomal losses (monosomy), found in the primary tumors.

Diagnosis of renal tumors on needle biopsy specimens by histological and molecular analysis

PURPOSE

We diagnosed the subtypes of renal cell carcinoma on needle core biopsies using a combination of histopathology and a molecular diagnostic algorithm.

MATERIALS AND METHODS

Core biopsies were taken of renal tumors following nephrectomy. RNA was extracted and quantitative real-time polymerase chain reaction was performed for 4 gene products to differentiate among renal cell carcinoma subtypes. Histopathological diagnosis was achieved on a second core before and after obtaining the molecular diagnostic algorithm results.

RESULTS

Based on the nephrectomy diagnosis 6 of 77 renal masses were nonneoplastic and 71 were tumors, including 65 renal cell carcinoma/oncocytomas. The overall diagnostic accuracy using histology and our molecular diagnostic algorithm combined was 90.0% (70 of 77). Side by side comparison of histology vs molecular diagnostic algorithm was feasible for 60 classifiable renal cell carcinoma/oncocytomas (31 clear cell, 14 papillary renal cell carcinoma, 6 chromophobe renal cell carcinoma, 2 mucinous tubular and spindle cell carcinoma, and 7 oncocytoma). In this group histology correctly predicted the final histological subtype in 83.3% (50 of 60) of cores. Addition of the molecular diagnostic algorithm to histology improved the subtyping accuracy to 95% (57 of 60), whereas the molecular diagnostic algorithm alone was accurate in 50 of 60 cases (83.3%). Dividing these 60 specimens into clear cell and nonclear cell neoplasms, the addition of the molecular diagnostic algorithm improved the sensitivity for the diagnosis of clear cell carcinoma from 87.1% (27 of 31) to 100% and the negative predictive value from 87.5% to 100%.

CONCLUSIONS

Core biopsies of renal tumors provide adequate material for diagnosing and subtyping renal cell carcinoma. The addition of our molecular diagnostic algorithm to histology improved the diagnostic accuracy of core biopsies of renal masses.

Common and uncommon histologic subtypes of renal cell carcinoma: imaging spectrum with pathologic correlation

Renal cell carcinoma (RCC) is a cause of significant morbidity and mortality, with an estimated 35,000 new cases and 12,480 deaths in the United States in 2003. Recent advances in imaging technology, pathology, urology, and oncology permit early diagnosis of RCC and facilitate optimal management. The 2004 World Health Organization classification for renal neoplasms recognizes several distinct histologic subtypes of RCC. These subtypes include clear cell RCC, papillary RCC, chromophobe RCC, hereditary cancer syndromes, multilocular cystic RCC, collecting duct carcinoma, medullary carcinoma, mucinous tubular and spindle cell carcinoma, neuroblastoma-associated RCC, Xp11.2 translocation-TFE3 carcinoma, and unclassified lesions. Different histologic subtypes of RCC have characteristic histomorphologic and biologic profiles. Clear cell RCC is the most common subtype and has a less favorable prognosis (stage for stage) than do papillary RCC and chromophobe RCC. Collecting duct carcinoma and renal medullary carcinoma are associated with aggressive clinical behavior and a poor prognosis.