Translocation (X;1) in papillary renal cell carcinoma. A new cytogenetic subtype

Incidental Detection of TFEB-Amplified Renal Cell Carcinoma by Colocated Gene Amplification of CCND3 (6p21): A Case Report and Review of the Literature

TFEB-amplified renal cell carcinoma (RCC), which belongs to the MITF family of RCC, is characterized by genomic amplification at the 6p21.1 locus where the TFEB gene is located. The vascular endothelial growth factor A and cyclin D3 genes are also located at this same locus. When tumors lack classic morphologic features, they may be classified as "RCC not otherwise specified (NOS)." However, it is increasingly important to accurately diagnose the RCC subtype to define the patient's individual prognosis and select the subsequent therapeutic modalities, which now include targeted agents. Therefore, knowledge of the diagnostic features of TFEB-altered RCCs, such as t(6;11) RCCs and TFEB-amplified RCCs, is critical for identifying these tumors. Herein, we present an interesting case of TFEB-amplified RCC that was initially diagnosed as RCC NOS on biopsy of a renal tumor in a community practice setting with available molecular findings demonstrating CCND3 amplification. The genetic abnormality was "accidentally" detected due to the amplification of the colocated CCND3 gene at the 6p21 locus of the TFEB gene on a limited genetic sequencing panel. This case highlights the importance of molecular tests in accurately diagnosing RCC and carefully interpreting molecular findings in the context of histomorphologic features.

Chameleon TFE3-translocation RCC and How Gene Partners Can Change Morphology: Accurate Diagnosis Using Contemporary Modalities

Translocation renal cell carcinoma (tRCC) with TFE3 gene rearrangements has been born as a distinct entity 20 years ago. These relatively rare tumors were notable among other RCC subtypes because of their disproportionally high incidence among children and young adults. Initial reports were focused on describing unifying morphologic criteria and typical clinical presentation. Follow-up studies of ancillary immunohistochemical and hybridization techniques provided additional diagnostic tools allowing recognition of tRCC tumors in practice. However, a growing body of literature also expanded the clinicomorphologic spectrum of tRCCs, to include a significant morphologic overlap with other RCC variants thus blurring the diagnostic clarity of this entity. More recent molecular studies utilizing next-generation sequencing technology accelerated recognition of numerous novel gene partners fusing at different breakpoints with the TFE3 gene. Accumulating data indicates that morphologic and clinical heterogeneity of tRCC could be explained by fusion subtypes, and knowledge of TFE3 partnering genes may be important in predicting tumor behavior. Herein we provided a comprehensive analysis of ∼400 tRCC cases with known TFE3 fusion partners, estimated their relative incidence and summarized clinicomorphologic features associated with most common fusion subtypes. Our data was based on an extensive literature review and had a special focus on comparing immunohistochemistry, fluorescent in situ hybridization and contemporary molecular studies for the accurate diagnosis of tRCC.

Towards a new WHO classification of renal cell tumor: what the clinician needs to know-a narrative review

In 1952, renal cell carcinomas had been divided into 2 categories—clear cell or granular cell—depending upon their cytoplasmic staining characteristics. In the following years, the inventory of renal epithelial tumors has expanded by the addition of tumors named by their architectural pattern (i.e., papillary RCC, tubulocystic RCC), anatomic location (i.e., collecting duct carcinoma, renal medullary carcinoma), associated diseases (i.e., acquired cystic disease-associated RCCs). With the extensive application of molecular diagnostic techniques, it becomes possible to detect genetic distinctions between various types of renal neoplasm and discover new entities, otherwise misdiagnosed or diagnosed as unclassified RCC. Some tumors such as ALK rearrangement-associated RCC, MiT family translocation renal carcinomas, SDH-deficient renal cancer or FH-deficient RCC, are defined by their molecular characteristics. The most recent World Health Organization (WHO) classification of renal neoplasms account for more than 50 entities and provisional entities. New entities might be included in the upcoming WHO classification. The aim of this review is to summarise and discuss the newly acquired data and evidence on the clinical, pathological, molecular features and on the prognosis of new RCC entities, which will hopefully increase the awareness and the acceptance of these entities among clinicians and improve prognostication for individual patients.

Morphologic and Immunohistochemical Characteristics of Fluorescent In Situ Hybridization Confirmed TFE3-Gene Fusion Associated Renal Cell Carcinoma: A Single Institutional Cohort

TFE3-fusion associated renal cell carcinoma (TFE3-RCC) accounts for up to 5% adults and 40% of childhood RCC. Their comprehensive immunohistochemical (IHC) profile in correlation to fluorescence in situ hybridization (FISH) testing and their role in the diagnostic approach are not well documented because of lacking published data. FISH confirmed TFE3-RCC between years 2010 and 2020 were identified from institutional electronic database and retrospectively reviewed. Eighty-five TFE3-RCC were identified. Seventy-six of 85 (89.4%) TFE3-RCC cases had positive TFE3 expression, with diffuse and strong/moderate TFE3 expression in 45 (54.2%). Three (3.5%) TFE3-RCC had negative TFE3 expression whereas 6 (7%) cases had equivocal TFE3 expression. On the other hand, positive TFE3-IHC expression was observed in 17/29 (58.6%) TFE3-FISH negative RCC cases, although only 8 (27.5%) had diffuse and moderate/strong TFE3 expression. Diffuse and strong TFE3-IHC expression was statistically significant in predicting TFE3-FISH positivity (P<0.0001) regardless of morphologic features. After univariate and multivariate analyses, TFE3-IHC was the only parameter with significant predictive value for detecting positive TFE3-FISH (P<0.0001). On univariate analysis, sex, classic morphology, age, negative AE1/AE3 or cytokeratin 7 were not predictive of TFE3-FISH positivity. Diffuse and strong nuclear TFE3-IHC expression is significantly associated with TFE3-FISH positivity and can be used as a surrogate marker to confirm translocation associated cases. TFE3-rearranged RCCs show variable histomorphologic features and TFE3-FISH should be performed in cases presenting at a younger age or, regardless of the age, tumors with unusual morphology. Despite previous reports, negative pancytokeratin and positive cathepsin K expression may not be reliable markers for TFE3-RCC.

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

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

PRCC-TFE3 dual-fusion FISH assay: A new method for identifying PRCC-TFE3 renal cell carcinoma in paraffin-embedded tissue

PRCC-TFE3 renal cell carcinoma (RCC) is one of the most common types of Xp11.2 translocation renal cell carcinoma (tRCC), of which the diagnosis mainly relies on reverse transcription-polymerase chain reaction (RT-PCR) or chromosomal analysis in fresh frozen samples. Herein, we developed a new dual-fusion fluorescence in situ hybridization (FISH) probe to succinctly identify PRCC-TFE3 RCC in paraffin-embedded tissue. We immunohistochemically analyzed TFE3 and cathepsin K expression in 23 cases of Xp11.2 tRCC which had been confirmed by break-apart TFE3 FISH probe. Next, the dual-fusion FISH assay was performed on these selected cases. Twenty typical cases of clear renal cell carcinoma and 20 cases of papillary renal cell carcinoma were collected as control groups. Seven cases were finally confirmed as PRCC-TFE3 RCC by FISH detection, emerging dual-fusion signals, of which 2 cases were identified as PRCC-TFE3 RCC by RT-PCR previously. All remaining cases were negative for the PRCC-TFE3 rearrangement by FISH. The TFE3 immunohistochemistry was positive in 22/23 cases and the cathepsin K was positive in 16/23 cases. All 7 PRCC-TFE3 RCCs showed positive cathepsin K immunoreactivity. Our results reveal that PRCC-TFE3 dual-fusion FISH probe is an efficient and concise technique for diagnosing PRCC-TFE3 RCC in paraffin-embedded tissue.

Validation and utilization of a TFE3 break-apart FISH assay for Xp11.2 translocation renal cell carcinoma and alveolar soft part sarcoma

Background

Xp11.2 or TFE3 translocation renal cell carcinomas (RCC) and alveolar soft part sarcoma (ASPS) are characterized by chromosome translocations involving the Xp11.2 breakpoint resulting in transcription factor TFE3 gene fusions. The most common translocations documented in TFE3 RCCs are t(X;1) (p11.2;q21) and t(X;17) (p11.2;q25) which leads to fusion of TFE3 gene on Xp11.2 with PRCC or ASPL respectively. TFE3 immunohistochemistry (IHC) has been inconsistent over time due to background staining problems in part related to fixation issues. Karyotyping to detect TFE3 gene rearrangement requires typically unavailable fresh tissue. Reverse transcriptase-polymerase chain reaction (RT-PCR) is generally very challenging due to degradation of RNA in archival material. The study objective was to develop and validate a TFE3 break-apart fluorescence in situ hybridization (FISH) assay to confirm Xp11 translocation RCCs and ASPS.

Methods

Representative sections of formalin-fixed paraffin-embedded tissue blocks were selected in 40 possible cases. Approximately 60 tumor cells were analyzed in the targeted region. The validation of TFE3 FISH was done with 11 negative and two positive cases. Cut off for a positive result was validated as >7.15 % positive nuclei with any pattern of break-apart signals. FISH evaluation was done blinded of the immunohistochemical or karyotype data.

Results

Three out of forty cases were positive for the TFE3 break-apart signals by FISH. The negative cases were reported as clear cell RCC with papillary features (10), clear cell RCC with sarcomatoid areas (2), Papillary RCC with clear cell areas (9), Chromophobe RCC (2), RCC, unclassified type (3) and renal medullary carcinoma (1). 3 of the negative cases were consultation cases for renal tumor with unknown histology. Seven negative cases were soft tissue tumor suspicious for ASPS.

Conclusion

Our study validates the utility of TFE3 break-apart FISH on formalin-fixed paraffin-embedded tissue sections for diagnosis and confirmation of Xp11.2 translocation RCCs and ASPS.

Accessory proteins for heterotrimeric G-proteins in the kidney

Heterotrimeric G-proteins play a fundamentally important role in regulating signal transduction pathways in the kidney. Accessory proteins are being identified as direct binding partners for heterotrimeric G-protein α or βγ subunits to promote more diverse mechanisms by which G-protein signaling is controlled. In some instances, accessory proteins can modulate the signaling magnitude, localization, and duration following the activation of cell membrane-associated receptors. Alternatively, accessory proteins complexed with their G-protein α or βγ subunits can promote non-canonical models of signaling activity within the cell. In this review, we will highlight the expression profile, localization and functional importance of these newly identified accessory proteins to control the function of select G-protein subunits under normal and various disease conditions observed in the kidney.

Papillary renal cell carcinoma: A review of the current therapeutic landscape

Renal cell carcinoma (RCC) is the most common cancer of the kidney and accounts for 2-3% of all adult malignancies. Clear cell carcinoma represents the most common histologic subtype, while papillary Renal Cell Carcinoma (pRCC) accounts for 10-20% of all renal cell cancers. While the inactivation of VHL gene can be found in the majority of clear cell carcinomas, different molecular mechanisms are involved into pRCC biology. Mutations in the MET oncogene are an essential step into the pathogenesis of hereditary pRCC forms, but they can be found only in a small rate of sporadic cases. Several agents, including anti-VEGF drugs and mTOR inhibitors, are possible options in the treatment of advanced and metastatic pRCC, following the demonstration of efficacy obtained in clinical trials including all RCC histologic subtypes. However, data specifically obtained in the subgroup of patients affected by pRCC are limited and not conclusive. Several ongoing trials are evaluating the efficacy of targeted therapy in papillary form. However, more rationale approaches based on molecular studies would help improving the outcome of these patients. Among others, MET inhibitors and targeted immunotherapy are promising new strategies for hereditary and sporadic disease. This review summarizes current knowledge on pRCC tumorigenesis and discusses recent and ongoing clinical trials with new therapeutic agents.

Characterization of adolescent and pediatric renal cell carcinoma: A report from the Children's Oncology Group study AREN03B2

BACKGROUND

The current study was conducted to characterize the epidemiology, histology, and radiographic features of as well as the surgical approach to pediatric and adolescent renal cell carcinoma (pRCC).

METHODS

pRCC cases prospectively enrolled on the Children's Oncology Group study AREN03B2 underwent central pathology, radiology, surgery, and oncology review.

RESULTS

As of June 2012, 120 of a total of 3250 patients enrolled on AREN03B2 (3.7%) were found to have unilateral RCC (median age, 12.9 years [range, 1.9-22.1 years]; 52.5% were female). Central review classified these as translocation morphology (56 patients), papillary (20 patients), renal medullary carcinoma (13 patients), chromophobe (4 patients), oncocytoma (1 patient), conventional clear cell (1 patient), and RCC not otherwise specified (25 patients). Lymph node (LN) involvement (N+) was found in 35 of 73 cases (47.9%) for which LNs were sampled, including 19 of 40 cases with primary tumors measuring <7 cm (47.5%). Using a size cutoff of 1 cm, imaging detection of LN involvement had a sensitivity of 57.14% (20 of 35 cases; 95% CI, 39.35%-73.68%) and a specificity of 94.59% (35 of 37 cases; 95% CI, 81.81%-99.34%). Distant metastases were present in 23 cases (19.2%). Initial surgery was radical nephrectomy in 88 patients (73.3%), nephron-sparing surgery in 18 patients (15.0%), and biopsy in 14 patients (11.7%). Compared with patients undergoing radical nephrectomy, those treated with nephron-sparing surgery were less likely to have LNs sampled (6 of 18 patients [33.3%] vs 65 of 88 patients [73.9%]; P = .002).

CONCLUSIONS

Translocation RCC is the most common form of pediatric and adolescent RCC. Lymph node disease is common and observed among patients with small primary tumors. Imaging has a high specificity but relatively low sensitivity for the detection of such lymph node disease. Failure to sample LNs results in incomplete staging and potentially inadequate disease control for younger patients with RCC.

Activators of G protein signaling in the kidney

Heterotrimeric G proteins play a crucial role in regulating signal processing to maintain normal cellular homeostasis, and subtle perturbations in its activity can potentially lead to the pathogenesis of renal disorders or diseases. Cell-surface receptors and accessory proteins, which normally modify and organize the coupling of individual G protein subunits, contribute to the regulation of heterotrimeric G protein activity and their convergence and/or divergence of downstream signaling initiated by effector systems. Activators of G protein signaling (AGS) are a family of accessory proteins that intervene at multiple distinct points during the activation-inactivation cycle of G proteins, even in the absence of receptor stimulation. Perturbations in the expression of individual AGS proteins have been reported to modulate signal transduction pathways in a wide array of diseases and disorders within the brain, heart, immune system, and more recently, the kidney. This review will provide an overview of the expression profile, localization, and putative biologic role of the AGS family in the context of normal and diseased states of the kidney.

Molecular genetics and cellular features of TFE3 and TFEB fusion kidney cancers

Despite nearly two decades passing since the discovery of gene fusions involving TFE3 or TFEB in sporadic renal cell carcinoma (RCC), the molecular mechanisms underlying the renal-specific tumorigenesis of these genes remain largely unclear. The recently published findings of The Cancer Genome Atlas Network reported that five of the 416 surveyed clear cell RCC tumours (1.2%) harboured SFPQ-TFE3 fusions, providing further evidence for the importance of gene fusions. A total of five TFE3 gene fusions (PRCC-TFE3, ASPSCR1-TFE3, SFPQ-TFE3, NONO-TFE3, and CLTC-TFE3) and one TFEB gene fusion (MALAT1-TFEB) have been identified in RCC tumours and characterized at the mRNA transcript level. A multitude of molecular pathways well-described in carcinogenesis are regulated in part by TFE3 or TFEB proteins, including activation of TGFβ and ETS transcription factors, E-cadherin expression, CD40L-dependent lymphocyte activation, mTORC1 signalling, insulin-dependent metabolism regulation, folliculin signalling, and retinoblastoma-dependent cell cycle arrest. Determining which pathways are most important to RCC oncogenesis will be critical in discovering the most promising therapeutic targets for this disease.

TFE3 Translocation-Associated Renal Cell Carcinoma Presenting as Avascular Necrosis of the Femur in a 19-Year-Old Patient: Case Report and Review of the Literature

In the United States, renal cell carcinoma (RCC) accounts for approximately 3% of adult malignancies and 90–95% of all neoplasms arising from the kidney. According to the National Cancer Institute, 58 240 new cases and 13 040 deaths from renal cancer will occur in 2010. RCC usually occurs in older adults between the ages of 50 and 70 and is rare in young adults and children. We describe a case of a TFE3 translocation-associated RCC in a 19-year-old patient presenting as avascular necrosis of the femur. Due to the rarity of this malignancy, we present this case including a review of the existing literature relative to diagnosis and treatment.

A case of renal cell carcinoma after successful treatment of Wilms tumor

This case report documents the eighth reported case of renal cell carcinoma (RCC) occurring after treatment of Wilms tumor. Although secondary malignancies after treatment of Wilms tumors are not infrequent, RCC as the second malignancy is rare. We discuss a 17-year-old girl whose RCC was diagnosed 12.5 years after diagnosis of a Wilms tumor. In addition, we review the literature on the subject. Renal cell carcinoma has been proposed as a consequent of chemoradiation; however, a genetic susceptibility must be considered. Because it is routine to assess the functional status of the remaining solitary kidney by annual ultrasonography, we recommend assessing for the presence of secondary renal malignancies and perhaps continuing routine ultrasounds long-term.

Translocations in epithelial cancers

Genomic translocations leading to the expression of chimeric transcripts characterize several hematologic, mesenchymal and epithelial malignancies. While several gene fusions have been linked to essential molecular events in hematologic malignancies, the identification and characterization of recurrent chimeric transcripts in epithelial cancers has been limited. However, the recent discovery of the recurrent gene fusions in prostate cancer has sparked a revitalization of the quest to identify novel rearrangements in epithelial malignancies. Here, the molecular mechanisms of gene fusions that drive several epithelial cancers and the recent technological advances that increase the speed and reliability of recurrent gene fusion discovery are explored.

Genetic profiles in renal tumors

Renal cell carcinoma in adult comprises a heterogeneous group of tumors with variable clinical outcomes, which ranges from indolent to aggressively malignant. The application of molecular genetics techniques to the study of renal neoplasms has resulted in improved classification of these entities and better understanding of biological mechanisms responsible for tumor development and progression. In the present article we review the molecular genetic profiles of different renal cell tumors and discuss their relevance to the carcinogenesis mechanisms and to the clinical diagnosis of renal cell carcinoma. Understanding of the molecular genetics of renal tumors is beneficial in making accurate diagnoses, assessing prognoses, and selecting appropriate and targeted therapeutic options.

Recent developments in the pathology of renal tumors: morphology and molecular characteristics of select entities

CONTEXT

Renal cell carcinoma is a heterogeneous group of tumors with distinct histopathologic features, molecular characteristics, and clinical outcome. These tumors can be sporadic as well as familial or associated with syndromes. The genetic abnormalities underlying these syndromes have been identified and were subsequently found in corresponding sporadic renal tumors.

OBJECTIVE

To review the recent molecular and genetic advancements relating to sporadic and familial renal carcinomas as well as those related to Xp11.2 translocation-associated renal cell carcinoma and renal medullary carcinoma.

DATA SOURCES

Literature review, personal experience, and material from the University of Chicago.

CONCLUSIONS

Molecular genetic diagnostic techniques will continue to introduce new biomarkers that will aid in the differential diagnosis of difficult cases. The identification of specific signaling pathways that are defective in certain renal tumors also makes possible the development of new therapies that selectively target the aberrant activity of the defective proteins.

Chromosomal translocations in cancer

Genetic alterations in DNA can lead to cancer when it is present in proto-oncogenes, tumor suppressor genes, DNA repair genes etc. Examples of such alterations include deletions, inversions and chromosomal translocations. Among these rearrangements chromosomal translocations are considered as the primary cause for many cancers including lymphoma, leukemia and some solid tumors. Chromosomal translocations in certain cases can result either in the fusion of genes or in bringing genes close to enhancer or promoter elements, hence leading to their altered expression. Moreover, chromosomal translocations are used as diagnostic markers for cancer and its therapeutics. In the first part of this review, we summarize the well-studied chromosomal translocations in cancer. Although the mechanism of formation of most of these translocations is still unclear, in the second part we discuss the recent advances in this area of research.

Renal translocation carcinomas: clinicopathologic, immunohistochemical, and gene expression profiling analysis of 31 cases with a review of the literature

We report clinicopathologic features of a large series of renal translocation carcinomas from a multicentric study. Diagnosis was performed by cytogenetic examination of fresh material and/or by immunochemistry with antibodies directed against the C-terminal part of transcription factor E3 (TFE3) and native transcription factor EB (TFEB) proteins. Clinical data, follow-up, and histologic features were assessed. Antibodies against CK7, CD10, vimentin, epithelial membrane antigen, AE1-AE3, E-cadherin, alpha-methylacyl-coenzyme A racemase, melan A, and HMB45 were tested on tissue microarrays. Whole-genome microarray expression profiling was performed on 4 tumors. Twenty-nine cases were diagnosed as TFE3 and 2 as TFEB renal translocation carcinomas, including 13 males and 18 females, mean age 24.6 years. Two patients had a previous history of chemotherapy and 1 had a history of renal failure. Mean size of the tumor was 6.9 cm. Thirteen cases were > or = pT3 stage. Twelve cases were N+ or M+. Mean follow-up was 29.5 months. Three patients presented metastases and 5 have died. Mixed papillary and nested patterns with clear and/or eosinophilic cells represented the most consistent histologic appearance, with common foci of calcifications regardless of the type of translocation. Using a 30 mn incubation at room temperature, TFE3 immunostainings were positive in only 82% of our TFE3 translocation carcinomas. Both TFE3 and TFEB renal translocation carcinomas expressed CD10 and alpha-methylacyl-coenzyme A racemase in all cases. An expression of E-cadherin was observed in two-third of cases. Cytokeratins were expressed in less than one-third of cases. Melanocytic markers were expressed at least weakly in all cases except two. Unsupervised clustering on the basis of the gene expression profiling indicated a distinct subgroup of tumors. TRIM 63 glutathione S-transferase A1 and alanyl aminopeptidase are the main differentially expressed genes for this group of tumors. Our results suggest that these differentially expressed genes may serve as novel diagnostic or prognostic markers.

Translocation renal cell carcinoma: lack of negative impact due to lymph node spread

BACKGROUND

Pediatric renal cell carcinoma (RCC) is clinically distinct from adult RCC. Characterization of the unique biological and clinical features of pediatric RCC are required.

METHODS

A retrospective review and biological analysis of all RCC cases presenting to Cincinnati Children's Hospital Medical Center (CCHMC) in the last 30 years was undertaken. Cases were classified according to the recent World Heath Organization morphologic classification and according to TFE3/TFEB status. A literature review of pediatric TFE+ cases was performed.

RESULTS

Eleven cases of RCC with clinical data were identified in our institutional review as follows: 6 clear cell, 2 papillary, 2 translocation, and 1 sarcomatoid. Upon reanalysis, 1 papillary and 1 sarcomatoid were confirmed, 1 case was "unclassified", and 8 of 11 (72.7%) had features consistent with translocation morphology. Of these 8, all demonstrated immunoreactivity for TFE3 (7 patients) or TFEB (1 patient) protein. In 3 cases, cytogenetics was available, each demonstrating confirmatory MiTF/TFE translocations. Seven of 8 TFE+ RCC patients presented with TNM Stage III/IV disease. Literature analysis confirmed a significant increase in advanced stage presentation in pediatric TFE+ RCC compared with TFE- RCC. Fourteen of fifteen (93.3%) patients with TFE+ stage III/IV RCC due to lymph node spread (N+ M(0)) remain disease free with a median and mean follow-up of 4.4 and 6.3 years, respectively (range, 0.3-15.5).

CONCLUSIONS

Translocation morphology RCC is the predominant form of pediatric RCC, associated with an advanced stage at presentation. Patients with TFE+ N+ M(0) RCC maintain a favorable short-term prognosis after surgery alone. Young RCC patients should be screened for translocation morphology, and the screening information should be considered when debating adjuvant therapy.

Molecular mechanisms underlying the MiT translocation subgroup of renal cell carcinomas

Renal cell carcinomas (RCCs) represent a heterogeneous group of neoplasms, which differ in histological, pathologic and clinical characteristics. The tumors originate from different locations within the nephron and are accompanied by different recurrent (cyto)genetic anomalies. Recently, a novel subgroup of RCCs has been defined, i.e., the MiT translocation subgroup of RCCs. These tumors originate from the proximal tubule of the nephron, exhibit pleomorphic histological features including clear cell morphologies and papillary structures, and are found predominantly in children and young adults. In addition, these tumors are characterized by the occurrence of recurrent chromosomal translocations, which result in disruption and fusion of either the TFE3 or TFEB genes, both members of the MiT family of basic helix-loop-helix/leucine-zipper transcription factor genes. Hence the name MiT translocation subgroup of RCCs. In this review several features of this RCC subgroup will be discussed, including the molecular mechanisms that may underlie their development.

Part II: Treatment of primary malignant non-Wilms' renal tumours in children

Renal-cell carcinoma, clear-cell sarcoma, (congenital) mesoblastic nephroma, rhabdoid tumour, and renal medullary carcinoma form a heterogeneous group of childhood renal malignancies known as non-Wilms' tumours. Progress has been slow in improving the management of these tumours to decrease morbidity and increase survival. However, greater cooperation between national and international centres should engender specialisation, and an increased knowledge of the molecular biology of these tumours will inevitably lead to substantial progress over the next decade. This review is the second of two parts: the first part provided an updated review of the clinical presentation, imaging, and pathology of non-Wilms' tumours and this second part provides an updated review of the treatment of these tumours.

A case of renal cancer with TFE3 gene fusion in an elderly man. Clinical, radiological and surgical findings

Sporadic cases of a particular group of renal cancers associated with a translocation involving Xp11.2, known as the TFE3 transcription factor gene, have been reported in the last 20 years. The group was also classified in 2004 WHO kidney carcinoma classifications. A 79-year-old male patient was investigated at the outpatient department for gross intermittent hematuria. Sonography showed a spherical left kidney with increased total size, without evidence of the corticomedullary differentiation due to parenchymal dyshomogeneity with a neoplasm aspect. CT confirmed the sonographic left kidney findings and showed gross node involvement. Angiography did not show any pathological arterial circulation, but massive thrombotic involvement of the renal vein was evident. Radical nephrectomy with thrombectomy and staging lymphectomy were performed. At pathological examination the kidney parenchyma was completely substituted by white firm tissue. Microscopically the tumor was composed of papillary structures lined by epithelial cells with a clear cytoplasm. Multiple node metastases were found. Immunohistochemical examination showed negativity for epithelial markers (cytokeratin and epithelial membrane antigen) and reactivity for CD10 and TFE3. The genetic and histological aspects of this rare tumor are reported. In addition, we describe clinical, radiological and surgical findings.

Common cancers in adolescents

Adolescence, spanning 15-19 years of age, is a time of developmental transition from childhood to adult life. The spectrum of cancers affecting this age group reflects a similar transition. The common malignant diseases of childhood - leukemias, lymphomas, tumors of the central nervous system and embryonal solid tumors (such as nephroblastoma and neuroblastoma) - are replaced in relative frequency by sarcomas of bone and soft tissue, and tumors of the male and female genital tracts. Moreover, the epithelial tumors (carcinomas), so prevalent in adults, occur (albeit at much lower frequencies) in adolescents. Within individual tumor types, biological features may be distinctive in this age group. Examples are the high prevalence of poor prognostic determinants in acute lymphoblastic leukemia and histologically higher grade forms of astrocytic/glial tumors. Particular challenges in addressing the common tumors of adolescence include the development of better categorization, especially of soft tissue sarcomas, and exploring these diseases in this age group within the developing world where most adolescents reside.

A renal cell carcinoma with components of both chromophobe and papillary carcinoma

We report a case of a morphologically unusual renal cell carcinoma with features of both chromophobe and papillary carcinoma. Immunohistochemical analysis of high molecular weight cytokeratins (HMWCK), cytokeratin 7 (CK7), cytokeratin 19 (CK19), c-Kit, and alpha-methylacyl-CoA racemase (AMACR) demonstrated differential profiles for the two components of the tumor, consistent with the respective patterns commonly observed for pure chromophobe and papillary renal cell carcinomas. Specifically, the chromophobe tumor cells expressed CK7 and c-Kit weakly, while HMWCK, CK19, and AMACR were not detectable. In contrast, the papillary tumor cells expressed uniformly HMWCK, CK7, and c-Kit and focally CK19 and AMACR. Fluorescence in situ hybridization analysis of nuclei isolated from paraffin-embedded tumor tissue detected monosomy 1, disomy 7, and monosomy 17, a common and characteristic finding in chromophobe carcinomas, in a majority of, but not all tumor cells, whereas a population characterized by disomy 1, trisomy 7, and trisomy 17, a frequent finding in papillary carcinoma, was not identifiable. Electron microscopic analysis revealed numerous characteristic small cytoplasmic vesicles in the chromophobe areas, which were absent in the papillary component. This case illustrates the rare coexistence of two distinct and admixed histologic types of renal cell carcinoma.

Evidence of recurrent gene fusions in common epithelial tumors

Chromosomal aberrations that accompany carcinogenesis have been documented for almost half a century, with gene fusions being the most prevalent type of aberration. Gene fusions leading to generation of aberrant fusion proteins or aberrant expression of normal proteins are a potent route to carcinogenesis and have recently emerged as attractive therapeutic targets. Intriguingly, although gene fusions have been widely observed in hematological malignancies, they have been far less frequently described in the more-common epithelial carcinomas. It has been recently proposed that technical issues, rather than any fundamental dichotomy between hematological and solid cancers, account for the under-representation of gene fusions in epithelial cancers. Recent reports from our group support this contention and provide evidence of widespread recurrent gene fusions in prostate cancer using a novel analysis of gene-expression profiles. Here, we provide an appraisal of the state of the knowledge of gene fusions in epithelial cancers. Future implications of gene fusions in common epithelial cancers are also discussed.

PRCC-TFE3 renal cell carcinoma in a boy with a history of contralateral mesoblastic nephroma

The genetics of renal tumors in children is widely recognized. However, most of the studies published to date emphasize the association between Wilms tumor and the WT-1 gene. Recently, a unique translocation between the X chromosome and chromosome 1 or t(X;1) has been described in several reports of renal cell carcinomas (RCCs) diagnosed in children and adolescents that results in PRCC-TFE3 gene fusion. We report here a 9-year old African-American boy with a history of a right congenital mesoblastic nephroma treated with nephrectomy and followed by annual checkups. After 9 years, he was diagnosed with a mass at the hilum of the left kidney during the work-up of new-onset hypertension. A limited biopsy revealed densely hyalinized connective tissue that was initially interpreted to be a hyalinized contralateral mesoblastic nephroma. The child received chemotherapy, but the mass continued to grow. He underwent a left nephrectomy, and the pathology was diagnostic for a clear cell RCC. Chromosomal analysis disclosed a t(X;1)(p11.2;q21) translocation, which is known to result in a PRCC-TFE3 gene fusion. The tumor showed nuclear labeling for TFE3 protein by immunohistochemistry, supporting the above diagnosis. He has been on hemodialysis, is tumor free, and has not been receiving chemotherapy for 24 months. This is the first report of a RCC as a second malignant neoplasm in a child treated for a congenital mesoblastic nephroma.

Pediatric renal cell carcinoma: clinical, pathologic, and molecular abnormalities associated with the members of the mit transcription factor family

We describe the clinical features, outcome, pathology, cytogenetics, and molecular aspects of 13 pediatric papillary renal cell carcinomas during a 19-year period. Seven cases (54%) had translocations involving Xp11.2 (TFE3). They were identified by cytogenetic, molecular, and/or immunohistochemical analyses. All Xp11.2+ translocations were TFE3+ by immunostaining. Cytogenetic and/or polymerase chain reaction analyses identified 3 cases with t(X17) and 1 case with t(1;17), and all had additional translocations. Histologic features in common in TFE3+ tumors also were present in some TFE3- tumors. One TFE3- tumor had complex cytogenetic abnormalities, 55XY,+2,del(3)(p14),+7,+8,+12,+13,+16,+17,+20[11 ], and 2 cases had normal karyotypes. None had t(6;11)/TFEB+ immunostaining. Five cases had focal, weak MITF tumor immunostaining. The key clinical findings were as follows: (1) The presence of an Xp11.2 (TFE3) translocation frequently is associated with advanced stage at initial examination. (2) All patients who underwent complete, partial nephrectomy with clear margins (adequate only for stage 1) and resection of metastases were alive and relapse-free at last follow-up. (3) The mean +/- SD event-free survival and overall survival rates at 5 years were both 92% +/- 7.4%. (4) One patients with a TFE3+ and MITF+ tumor and 66-87,XXY,der(1)t(1;8)del(4)(q?) der(11)t(11;15)der17t(X;17 abnormalities died 9 months after diagnosis.

Fine-needle aspiration of a Xp11.2 translocation/TFE3 fusion renal cell carcinoma metastatic to the lung: Report of a case and review of the literature

A 57-yr-old woman presented to the National Cancer Institute (NCI) with a history of nephrectomy for a clear cell renal cell carcinoma (RCC), Fuhrman grade 3 of 4 diagnosed 1 yr prior to admission to the NCI. A CT scan done upon admission revealed multiple bilateral lung masses. A CT-guided fine-needle aspiration (FNA) of one of the lung masses revealed a cellular specimen composed primarily of follicular structures surrounding dense hyalinized central cores. The cells in the follicular structures displayed bland nuclei and had granular to vacuolated cytoplasm. Papillary structures were also appreciated. Immunocytochemical studies showed tumor cells that were strongly vimentin and TFE3 positive. Focal staining for AE1/AE3 and CD10 was observed, as was negative staining for EMA. A surgical biopsy specimen reflected the FNA findings and demonstrated a similar immunoprofile. These findings correspond to the recently described Xp11.2 translocation/TFE3 fusion renal cell carcinoma. To our knowledge, this is the first report describing the cytologic features of an Xp11.2 translocation/TFE3 fusion RCC.

Translocation carcinomas of the kidney

A significant proportion of RCCs of children and young adults bear specific chromosome translocations that result in gene fusions that involve members of the MiTF/TFE transcription factor family. These include the Xp11-translocation carcinomas, which bear TFE3 gene fusions, and the renal carcinomas with the t(6;11)(p21;q12), which bear an Alpha-TFEB gene fusion. Both types of translocation result in overexpression of the fusion gene products, such that nuclear labeling for TFE3 or TFEB by immunohistochemistry is a sensitive and specific marker of these respective tumor types. The clinical behavior of these neoplasms relative to conventional, adult-type renal carcinomas remains to be determined, and will be an important area of future investigation.

Application of molecular diagnostic techniques to renal epithelial neoplasms

The application of molecular and cytogenetic techniques to the study of renal neoplasia has resulted in improved understanding of the biologic mechanisms that are responsible for tumor development and progression. It also revealed that several different and specific genetic events are responsible for tumorigenesis in the various categories and subcategories of renal tumors. The ultimate goal of research on the molecular pathology of renal neoplasms is a complete understanding of the genetics of these tumors, which will, in turn, aid in making the correct diagnosis, accurately assessing prognosis, and selecting appropriate and targeted therapeutic options.

Pediatric renal tumors: practical updates for the pathologist

Pediatric renal tumors were targeted by the National Wilms Tumor Study Group for 4 decades with extraordinary success. Within this historic context, this review provides a summary of the new Children's Oncology Group renal tumor protocols that will be opening in the very near future, focusing on their pathologic requirements. All renal tumors must first be registered on the Renal Tumor Classification and Banking Protocol, followed by registration on 1 of 4 primary therapeutic protocols based on histology, stage, and molecular analysis. This requires prompt submission of samples for molecular analysis and central pathologic review. Changes in staging criteria include classification of all tumor spillage as stage III, and requirement of regional lymph node evaluation for eligibility for stage I Wilms tumors (WTs) weighing less than 550 g in infants younger than 24 months and for stage I clear cell sarcoma. Patients with unilateral favorable histology WT with loss of heterozygosity for chromosomes 1p and 16q will receive more aggressive chemotherapy at each stage. Patients with bilateral WT and patients with diffuse hyperplastic perilobar nephroblastomatosis will be eligible for a novel therapeutic protocol requiring pathologic classification based on response of tumor to previous therapy. Stage I anaplastic WT will be targeted with more aggressive chemotherapy than in the past. For the first time, pediatric renal cell carcinoma will be eligible for a cooperative group protocol. All rhabdoid tumors outside the central nervous system will be eligible for a single protocol. In conclusion, these new protocols bring considerable change in their overall organization, in eligibility, and in therapy.

Pediatric renal carcinoma associated with Xp11.2 translocations/TFE3 gene fusions and clinicopathologic associations

Renal cell carcinomas (RCCs) are rare in children and studies of their subtypes and clinicopathologic associations are limited to small series. We identified 8 patients with RCC treated at our institution between 1981 and 2003, reviewed their clinicopathologic features, cytogenetics findings, and evaluated the status of TFE3 expression by immunohistochemistry and numerical chromosomal alterations by interphase fluorescent in situ hybridization on paraffin-embedded tissue. These 8 patients (5 female and 3 male) had diploidy, and 5 had morphologic features compatible with the recently described RCC associated with Xp11.2 translocations/TFE3 gene fusions and demonstrated nuclear labeling for TFE3 protein by immunohistochemistry. The translocation was confirmed in 2 of these 5 patients by conventional cytogenetics. One case was a high-grade nonpapillary RCC and the other was compatible with type 2 papillary RCC. Four patients showed at least 1 chromosomal gain including trisomy 7 and/or trisomy 17. None of the tumors from male patients showed evidence of loss of the Y chromosome, but 2 patients showed numerical abnormalities of X chromosome +add(X). Two patients had sickle cell disease, and 1 of these also had stage IV-S neuroblastoma. This study suggests that many cases of RCC in children reported under the terms "papillary" and "clear cell" likely represent Xp11.2 translocation/TFE3 gene fusion-associated RCC. It also emphasizes the unusual associations of RCC with neuroblastoma and sickle cell hemoglobinopathy, which need further study.

Local lymph node involvement does not predict poor outcome in pediatric renal cell carcinoma

BACKGROUND

Local lymph node involvement in adults with renal cell carcinoma (RCC) is associated with poor outcome. The prognostic significance of local lymph node involvement in children with RCC has not been studied systematically.

METHODS

A retrospective review of patients treated at St Jude Children's Research Hospital (Memphis, TN) and an extensive review of the medical literature were undertaken to evaluate the prognostic significance of local lymph node involvement in pediatric RCC.

RESULTS

Thirteen patients with the diagnosis of RCC were treated at St. Jude since the hospital's inception in 1962. Four patients presented with lymph node-positive, distant metastasis-negative (N + M0) disease, and all 4 remain disease free after resection without adjuvant therapy (follow-up duration, 2-9 years). A systematic review of the literature including 243 pediatric patients with RCC revealed stage-specific survival rates of 92.5%, 84.6%, 72.7%, and 12.7% for Stage I-IV disease, respectively. Of 58 children with N + M0 RCC for whom outcome data were available, 42 (72.4%) were alive without disease at last follow-up. Among patients whose therapy could be discerned, those who received no adjuvant therapy fared as well (15 of 16 alive) as those who received various adjuvant treatments (22 of 31 alive).

CONCLUSIONS

Children with lymph node-positive RCC in the absence of distant metastatic disease had a relatively favorable long-term prognosis, with survival rate nearly triple those of adult historical controls. Until highly effective therapies for RCC are identified, these children should not be exposed to adjuvant treatment. Further investigation of the biologic differences between adult and pediatric RCC is warranted.

Recent advances in pediatric renal neoplasia

Over the past 6 years, molecular genetic studies have significantly advanced our understanding of pediatric renal neoplasms. The cellular variant of congenital mesoblastic nephroma (but not the classic variant) has been shown to bear the same t(12;15)(p13;q25) and ETV6-NTRK3 gene fusion as infantile fibrosarcoma, a tumor with which it shares morphologic and clinical features. Rhabdoid tumor of the kidney is characterized by deletion of the hSNF5/INI1 gene, which links it to other rhabdoid tumors of infancy that arise in the soft tissue and brain. Primary renal synovial sarcomas and renal primitive neuroectodermal tumors have become accepted entities, and likely comprise a subset of what had previously been termed "adult Wilms tumor." Renal carcinomas associated with Xp11.2 translocations that result in fusions involving the TFE3 transcription factor gene have been delineated, including a distinctive neoplasm that shares the identical gene fusion as alveolar soft part sarcoma. Most recently, a distinctive type of renal neoplasm with a t(6;11)(p21;q12) has been described, and the cloning of the resulting gene fusion links it to the Xp11 translocation carcinomas. Together, these last two translocation-associated tumors represent a significant proportion of pediatric renal cell carcinomas. This review highlights each of these recent advances.

Five new cases of juvenile renal cell carcinoma with translocations involving Xp11.2: a cytogenetic and morphologic study

Two cases of renal cell carcinoma (RCC) carrying a t(X;1)(p11.2;q21) in a 12-year-old boy and a 14 year-old girl, two cases with a t(X;1)(p11.2;p34) in a 9-year-old boy and a 31-year-old woman, and one case with a t(X;17)(p11.2;q25) in a 15-year-old boy are reported. Two are likely papillary RCC, with clear or slightly eosinophilic cells, and two to a clear cell RCC; one shows a mixture of papillary and clear cell RCC architecture. Renal cell carcinomas with translocations involving Xp11.2 form a specific entity characterized by subtle pathologic features and younger age of occurrence, especially for those with the t(X;17).

PRCC-TFE3 renal carcinomas: morphologic, immunohistochemical, ultrastructural, and molecular analysis of an entity associated with the t(X;1)(p11.2;q21)

The reappraisal of genetically defined subsets of renal tumors can help to highlight the key pathologic features of specific neoplastic entities. We report the morphologic, immunophenotypic, ultrastructural, and molecular features of 11 renal carcinomas bearing a t(X;1)(p11.2;q21) and/or the resulting PRCC-TFE3 gene fusion. The male/female ratio was 4:7. Ten patients were in the age range of 9-29 years and one was 64 years old (mean 21.3 years, median 15 years). The predominant histologic pattern was nested, with islands of tumor cells compartmentalized by thin-walled capillary vasculature. Minor variations on this pattern yielded solid, acinar, alveolar, and tubular architecture. Papillary architecture was seen in nine cases, usually as a minor component. Neoplastic cells were typically characterized by irregularly shaped nuclei with vesicular chromatin and small nucleoli not visible with a 10x objective, and cytoplasm that ranged from clear to densely granular and eosinophilic. Mitoses were extremely rare; 5 were found in 900 high power fields examined from the 11 neoplasms. The most distinctive immunohistochemical feature of these neoplasms was moderate to intense nuclear labeling for TFE3 protein. These tumors were also consistently immunoreactive for the RCC antigen (10 of 11) and CD10 (9 of 9), whereas cytokeratin and epithelial membrane antigen were negative in four cases and were positive focally in the others. Ultrastructurally, all of the six neoplasms examined showed features consistent with conventional-type (clear cell) renal carcinoma, although two demonstrated distinctive intracisternal microtubules. Both tumors tested contained PRCC-TFE3 fusion transcripts. The differential diagnosis includes conventional-type papillary renal cell carcinoma, conventional-type (clear cell) renal carcinoma, and the ASPL-TFE3 renal carcinomas associated with the t(X;17)(p11.2;q25), with the latter two being morphologically the most similar to the t(X;1) renal carcinomas. Aside from their distinctive clinicopathologic features described here, there is experimental evidence suggesting that these tumors may show differential sensitivity to certain chemotherapeutic agents.

Renal cancer: cytogenetic and molecular genetic aspects

To date, much progress has been made in the fields of cytogenetics and molecular genetics of renal tumors. The previous and recent findings have delineated the characteristics of the various tumors, particularly the cytogenetic and molecular differences that exist between papillary and nonpapillary clear cell renal cell carcinomas (RCCs). At the same time, new cytogenetic subtypes have emerged [e.g., t(X;1)] in subtypes of RCC, while in others (e.g., Wilms tumors) several new cytogenetic abnormalities and consequent molecular involvement have been found. In addition to Wilms tumor, papillary RCC, and clear-cell RCC, cytogenetic and fluorescence in situ hybridization analyses have been performed on several other tumors of the kidney, including chromophobic carcinoma, metanephric adenoma, collecting duct carcinoma, transitional cell carcinoma, congenital mesoblastic nephroma, and malignant rhabdoid tumors of the kidney. This review is therefore intended to present a concise update on the cytogenetic and molecular data on renal tumors, focusing mainly on the clinical usefulness of the findings reported in the literature.

Subclassification of renal cell neoplasms: an update for the practising pathologist

The classification of renal cell neoplasms has been extensively studied in the last decade, and a standardized nomenclature adopted. Although this system is based on a combination of genetic, histological and immunohistological features, in most cases accurate classification can be based on histological features alone. This review summarizes the key features of the tumours included in this system, and then focuses on diagnostic difficulties that can arise when using this system, as well as reviewing several recently characterized tumours that are not yet included.

Unique patterns of allelic imbalance distinguish type 1 from type 2 sporadic papillary renal cell carcinoma

The molecular genetic correlates of a recently proposed subclassification of papillary renal cell carcinoma (PRCC) that designates tumors as type 1 and type 2 based on histological features have not yet been established. Alterations of known genes in PRCC include missense mutations in the MET oncogene (7q31) and rare translocations fusing TFE3 at Xp11.2 with a variety of other loci. Previous cytogenetic and allelic loss studies of PRCC cases revealed gain of chromosome 3q, 7, 8, 12q, 16, 17, and 20q, and loss of 1p, 6q, 9p, 11p, 13q, 14q, 18, 21q, X, and Y. We analyzed a series of sporadic type 1 and type 2 PRCC cases for MET mutations, TFE3 rearrangements, and allelic imbalance (AI) on 3p, 6, 7q, 9p, 11, 13q, 14q, 17q, 18, 20q, and 21q and compared selected results with a series of conventional renal cell carcinomas. A somatic mutation M1149T was identified in MET exon 17 in 1 of 35 PRCC cases whereas TFE3 rearrangements were not detected in 22 PRCC cases examined. Significant differences in AI frequency between PRCCs and conventional renal cell carcinoma cases were seen on 3p (37.5% versus 77.8%, P = 0.01), 7q (42.9% versus 5.6%, P = 0.01), and 17q (54.5% versus 20.0%, P = 0.03). Significant differences in AI frequency between type 1 and type 2 PRCCs were noted on 17q (78.6% versus 12.5%, P = 0.006) and 9p (0% versus 37.5%, P = 0.02). Additional analyses suggested that the relationship between 17q AI and PRCC type may be independent of histological grade and stage. Our findings identify genetic differences between the recently proposed type 1 and type 2 PRCCs, and support the premise that these subtypes arise from distinct genetic pathways.

Analysis of kidney tumors by comparative genomic hybridization and conventional cytogenetics

Comparative genomic hybridization (CGH) and conventional cytogenetic karyotyping were used to screen for losses and gains of DNA sequences along chromosomes in ten renal tumors (RCC) of different histologic types (clear-cell RCC, papillary RCC, and one oncocytoma). Loss of 3p was the most common change in clear-cell RCC. All papillary tumors, either adenomas or carcinomas revealed gains of chromosomes 7 and 17q without limitation to size and grade. Homozygotic loss of the pseudoautosomal Xp or Yp region was detected in three RCC tumors. A dicentric (Y;14) was present as the sole chromosome abnormality in the oncocytoma. Both techniques showed concordant results in tumors with homogeneous karyotype. However, in tumors with several composite clones some discrepancies were observed, especially in cases of clear-cell RCC where chromosomal abnormalities present in a low number of metaphases could not be detected by CGH.