Trisomy 19 ependymoma, a newly recognized genetico-histological association, including clear cell ependymoma

Methylation and molecular profiles of ependymoma: Influence of patient age and tumor anatomic location

Ependymomas are tumors of the central nervous system that can occur in patients of all ages. Guidelines from the World Health Organization (WHO) for the grading of ependymomas consider patient age, tumor resection range, tumor location and histopathological grade. However, recent studies have suggested that a greater focus on both tumor location and patient age in terms of transcriptomic, genetic, and epigenetic analyses may provide a more accurate assessment of clinical prognosis than the grading system proposed by WHO guidelines. The current study identified the differences and similarities in ependymoma characteristics using three different molecular analyses and methylation arrays. Primary intracranial ependymoma tissues were obtained from 13 Korean patients (9 adults and 4 children), after which whole-exome sequencing (WES), ion-proton comprehensive cancer panel (CCP) analysis, RNA sequencing, and Infinium HumanMethylation450 BeadChip array analysis was performed. Somatic mutations, copy number variations, and fusion genes were identified. It was observed that the methylation status and differentially expressed genes were significantly different according to tumor location and patient age. Several novel gene fusions and somatic mutations were identified, including a yes-associated protein 1 fusion mutation in a child with a good prognosis. Moreover, the methylation microarray revealed that genes associated with neurogenesis and neuron differentiation were hypermethylated in the adult group, whereas genes in the homeobox gene family were hypermethylated in the supratentorial (ST) group. The results confirmed the existence of significantly differentially expressed tumor-specific genes based on tumor location and patient age. These results provided valuable insight into the epigenetic and genetic profiles of intracranial ependymomas and uncovered potential strategies for the identification of location- and age-based ependymoma-related prognostic factors.

The Effects of Surgery and Adjuvant Therapy on Survival Outcomes in Clear Cell Ependymomas: A Systematic Review and Meta-Analysis of Individual Patient Data

BACKGROUND

The survival outcomes of clear cell ependymomas are poorly understood. This study clarifies the role of surgery and adjuvant therapy when this morphologically distinct tumor is encountered.

METHODS

A systematic search for studies relating to clear cell ependymomas was conducted. Primary outcomes were progression-free survival and overall survival. Prognostic variables were age, sex, tumor consistency, extent of resection, and postoperative adjuvant therapy. Kaplan-Meier survival curves were generated and compared by the log-rank test. Multivariate Cox regression models were constructed, interrogated with Schoenfeld residuals, and used to identify independent prognostic factors.

RESULTS

Of the 384 articles retrieved, 8 articles comprising 77 cases of clear cell ependymoma were included. Five-year overall survival and progression-free survival were 58.1% (95% confidence interval [CI], 46.3%-72.9%) and 46.3% (95% CI, 34.2%-62.8%), respectively. Kaplan-Meier analysis with the log-rank test showed that gross total resection was superior to subtotal resection in prolonging survival (P = 0.047) and delayed time to recurrence (P < 0.01). Multivariate analysis confirmed gross total resection as an independent protective factor against relapse (odds ratio, 0.39; 95% CI, 0.17-0.89; P = 0.03). Age <50 years predicted longer overall survival (odds ratio, 0.16; 95% CI, 0.05-0.49; P < 0.01). Postoperative adjuvant therapy after gross total resection did not affect overall survival (P = 0.98) or progression-free survival (P = 0.93). Adjuvant therapy after subtotal resection favored improved overall survival (P = 0.052).

CONCLUSIONS

Clear cell ependymomas are particularly aggressive in those aged >50 years. Gross total resection remains the cornerstone of management. Postoperative adjuvant therapy is likely to be of survival benefit only after subtotal resection.

TERTp Mutation Detection in Plasma by Droplet-Digital Polymerase Chain Reaction in Spinal Myxopapillary Ependymoma with Lung Metastases

BACKGROUND

Spinal myxopapillary ependymoma (SP-MPE) is a subgroup of ependymomas in which after initial gross tumor resection, recurrences occur in more than half of the patients. Anaplastic transformation may also occur and contributes to intraneural and extraneural metastatic dissemination. Extraneural metastases from SP-MPE are rare and worsen the prognosis. In this situation, the noninvasive detection of recurrent somatic mutations in the circulating tumor DNA (ctDNA) from plasma is challenging. Telomerase-reverse transcriptase gene promoter (TERTp) mutation has been identified in a subset of ependymomas with aggressive behavior.

CASE DESCRIPTION

We report on a patient with TERTp mutated SP-MPE presenting with an extraneural anaplastic metastatic dissemination after iterative local recurrences. From the initial SP-MPE to pleural anaplastic lesion, TERTp C228T mutation was present with allele frequency varying from 33% to 39%. Interestingly, TERTp mutation was also detected by droplet digital polymerase chain reaction in the plasma with a frequency of 2.1% at the time of pleural metastases, highlighting that ctDNA is released in plasma of patients suffering from SP-MPE with extraneural metastatic dissemination.

CONCLUSIONS

Despite the rarity of this evolution, plasmatic liquid biopsy appears to be a useful diagnostic and follow-up tool in a subset of primary brain tumors.

A De Novo Mouse Model of C11orf95-RELA Fusion-Driven Ependymoma Identifies Driver Functions in Addition to NF-κB

The majority of supratentorial ependymomas (ST-ependymomas) have few mutations but frequently display chromothripsis of chromosome 11q that generates a fusion between C11orf95 and RELA (RELAFUS). Neural stem cells transduced with RELAFUSex vivo form ependymomas when implanted in the brain. These tumors display enhanced NF-κB signaling, suggesting that this aberrant signal is the principal mechanism of oncogenesis. However, it is not known whether RELAFUS is sufficient to drive de novo ependymoma tumorigenesis in the brain and, if so, whether these tumors also arise from neural stem cells. We show that RELAFUS drives ST-ependymoma formation from periventricular neural stem cells in mice and that RELAFUS-induced tumorigenesis is likely dependent on a series of cell signaling pathways in addition to NF-κB.

Pediatric Thalamic Gliomas: An Updated Review

CONTEXT

- Neoplasms originating in the thalamus are rare overall (1% of all brain tumors); however, they comprise approximately 5% of pediatric intracranial tumors and approach 15% of all malignant pediatric intracranial tumors in some series.

OBJECTIVE

- To update readers about the current understanding of the diverse histology, biology, and behavior of pediatric thalamic tumors. Histologic verification is now thought to be critical for planning treatment, and, as a result, biopsy and total/subtotal resections are much more common today than in the past.

DATA SOURCES

- A PubMed search using the keywords "pediatric + thalamic + glioma" yielded 45 publications with a total of 445 cases of thalamic gliomas in patients less than 18 years of age. We found only 9 substantial institutional series tabulating all encountered thalamic histologic types in children. This survey confirmed a high proportion of astrocytomas, 81% (214 of 265), of which approximately two-thirds were diffuse astrocytomas (146 of 214) and one-third were pilocytic astrocytomas (68 of 214). Of the diffuse astrocytomas, 34% (49 of 146) were low grade (World Health Organization grade II) and 55% (81 of 146) were high grade (World Health Organization grade III or IV), making the latter subgroup the largest single category of all pediatric thalamic tumors. Oligodendrogliomas and ependymomas (mostly anaplastic in both cases) comprised 10% and 3% of all pediatric thalamic tumors, respectively.

CONCLUSIONS

- Tissue diagnosis is now thought crucial for prognostication and treatment, particularly as more potentially therapeutic molecular targets are discovered. Secure diagnosis allows identification of tumors for which resection is more feasible and beneficial.

Genomic Analysis in the Practice of Surgical Neuropathology: The Emory Experience

The evaluation of central nervous system tumors increasingly relies on molecular genetic methods to aid in classification, offer prognostic information, and predict response to therapy. Available assays make it possible to assess genetic losses, amplifications, translocations, mutations, or the expression levels of specific gene transcripts or proteins. Current molecular diagnostics frequently use a panel-based approach and whole genome analysis, and generally rely either on DNA sequencing or on hybridization-based methodologies, such as those used in cytogenomic microarrays. In some cases, immunohistochemistry can be used as a surrogate for genetic analysis when the mutation of interest consistently results in overexpression or underexpression of a known protein product. In surgical neuropathology practice, the diagnostic workup of diffuse gliomas, medulloblastomas, low-grade circumscribed gliomas, as well as other diseases, now routinely incorporates the results of genomic studies. Here we summarize our institution's current approach to diagnostic surgical neuropathology, using these contemporary molecular diagnostic applications.

[Pediatric ependymomas: Current diagnosis and therapy]

Ependymomas represent 10% of pediatric brain tumors. In the recent WHO 2016 classification, pathology is enriched by localization and molecular biology. Whatever the age, total removal by one or several looks when required remains a major prognostic factor. In children, focal radiation remains a standard, while the role of chemotherapy is matter of randomized studies. In infants, front line chemotherapy is the standard. Inclusion in the SIOP ependymoma II protocol is encouraged. In case of relapse, further surgery and radiation are advised, while inclusion in innovative trials including re-irradiation, and phase I-II should be encouraged. A better understanding of underlying mechanisms of ependymoma cell will provide in the close future, the key to use targeted therapies at time of relapse, and very soon as first line therapy for some subgroups of patients.

Supratentorial clear cell ependymomas with branching capillaries demonstrate characteristic clinicopathological features and pathological activation of nuclear factor-kappaB signaling

BACKGROUND

Clear cell ependymoma is one of the 4 main histological subtypes of ependymomas defined by the World Health Organization (WHO) classification of tumors of the CNS. DNA methylation profiling can distinguish 4 subgroups of intracranial ependymomas, including supratentorial (ST) ependymomas with Yes-associated protein 1 fusion (YAP1), ST ependymomas with fusion of v-rel avian reticuloendotheliosis viral oncogene homolog A (RELA), posterior fossa ependymomas with balanced genome, and posterior fossa ependymomas with chromosomal instability. In addition, trisomy 19 is a genomic hallmark of ependymomas with rich branching capillaries. However, the relation of histological and molecular subtypes is unclear.

METHODS

Here, we report a series of 20 ependymomas histologically defined by clear cells and branching capillaries.

RESULTS

We observed a strong male predominance. Median age at surgery was 10.4 years (range, 0.8-68.4). All cases were ST, cortical, contrast enhancing, and most often frontal, cystic, and calcified. All tumors qualified as WHO grade III. Some of them exhibited neuronal differentiation. Trisomy 19 was recorded in 13 cases. All samples strongly accumulated p65RelA protein within nuclei, indicating pathological activation of the nuclear factor-kappaB pathway. We identified causative C11ORF95-RELA fusion in almost all cases. Median progression-free survival and overall survival were 11.4 years (95% CI: 5.1-17.8) and not reached, respectively.

CONCLUSION

ST clear cell ependymomas with branching capillaries display characteristic clinicopathological features and are associated with pathological activation of nuclear factor-kappaB signaling, which may indicate a potential novel target for therapy in these patients.

Understanding Ependymoma Oncogenesis: an Update on Recent Molecular Advances and Current Perspectives

Remarkable progress has been made in the last decade in understanding the biology and oncogenesis of this relatively rare childhood brain tumor-the ependymoma. Surgery and irradiation are the mainstays of therapeutic options; chemotherapy is yet to predictably affect outcome, and its role is currently being explored in several clinical trials. While WHO scores this tumor into three grades, grading of ependymoma into grade II and grade III is controversial because of its elusive histological criteria where no cut-offs have been defined for mitoses or percentage of tumor depicting increased cellularity. Grading remains unreliable in predicting outcome in several instances. There is a compelling need to integrate the molecular biomarkers highlighted in several studies over the past decade into patient risk stratification to help in better predicting the clinical outcome and to design effective tailored therapy. Genomic and transcriptomic studies lately have defined distinct molecular subgroups within ependymoma arising at three anatomic compartments-supratentorial, posterior fossa, and spinal cord. Review of pertinent literature on several seminal studies that have established a paradigm shift in understanding the oncogenesis of ependymoma has been carried out. The outcome, impact, and clinical relevance of these studies are also discussed. The review provides an update on progress and recent advances in understanding the biology and oncogenesis of ependymoma. The establishment of robust subgroups which are demographically, clinically, and molecularly distinct will provide new avenues for further refinement of therapeutic strategies.

Long-term life expectancy for children with ependymoma and medulloblastoma

OBJECTIVES

There is a paucity of long-term follow-up data for children with intracranial ependymoma (IE) and medulloblastoma (MB). What happens to these children 20, 30, or 40 years after diagnosis? Do they have potential for a normal lifespan? The purpose of this study was to ascertain the long-term survival potential in children with MB or IE who have survived 5 years from diagnosis.

METHODS

A retrospective analysis was conducted using the SEER Program. Children (ages 0-19 years) from 1973 to 2011 with a diagnosis of MB or IE were identified. A cohort was created of potentially cured patients who survived 5 years from diagnosis. Cox proportional hazards models and Kaplan-Meier estimates were utilized to analyze long-term survival.

RESULTS

We identified 876 patients with MB and 474 patients with IE who were alive 5 years from diagnosis. Patients with MB had a 30-year overall survival (OS) and cancer-specific survival (CSS) of 70.2% and 80.1%, respectively. Patients with IE had a 30-year OS and CSS of 57.3% and 68.8%, respectively. When comparing MB with IE, MB had improved CSS (P = 0.04) and trended toward increased OS (P = 0.10).

CONCLUSIONS

A significant number of deaths due to disease occur for several decades after treatment for both IE and MB. Despite this, the potential for long-term survival exists in 5-year survivors of both histologies. If alive at 5 years from diagnosis, patients with MB tend to have a lower risk of death from disease compared to those with IE.

Supra- and infratentorial pediatric ependymomas differ significantly in NeuN, p75 and GFAP expression

Ependymomas comprise 8 % of all intracranial tumors in children <15 years. Recent studies revealed that some supratentorial ependymomas express neuronal antigens and that high expression of neurofilament protein light polypeptide (NEFL) correlates with better clinical outcome. We retrospectively analyzed an expanded panel of proteins in 6 supratentorial, 15 posterior fossa and 4 spinal pediatric ependymomas by immunohistochemistry. Expression of high and low affinity neurotrophin receptors TrkA (NTRK1) and p75 (NGFR), pan-neuronal markers NeuN (RBFOX3) and synaptophysin, radial glial marker SOX9, adhesion molecules CD56 (NCAM) and CD44, junctional protein connexin 43 (GJA1), glial fibrillary acidic protein (GFAP), epithelial membrane antigen and proliferation associated antigen Ki-67 were evaluated in a semi-quantitative or quantitative (Ki-67 and NeuN-index) fashion. We found p75 and NeuN to be expressed at significantly higher levels in supratentorial versus infratentorial tumors and GFAP to be expressed at significantly higher levels in infratentorial lesions. In conclusion, immunohistochemical expression of p75, NeuN and GFAP differed in ependymomas depending on tumor topography supporting the view of divergent cells of origin. However, because of the small sample size the results are of preliminary nature and replication in a larger cohort would be desirable.

Central nervous system tumors

Central nervous system tumors are the most frequent malignant tumor in children and the main cause of death in this age group after traffic accidents. The current estimates are that one adult in 2500 is a survivor of a brain tumor that occurred during childhood. These tumors are particularly heterogeneous in terms of histology/biology, treatment, and outcome. They share, however, a high risk of neurological and cognitive morbidity due to the disease itself and the treatment modalities (radiotherapy, surgery, and chemotherapy). Diagnosis is frequently delayed because symptoms are usually nonspecific at the beginning of the evolution. Posterior fossa is the most frequent site and the tumors present most frequently with signs of intracranial hypertension. Supratentorial tumors are more frequent in infants and in adolescents; seizures are not uncommon, especially for benign tumors. When adjuvant treatment is needed, radiotherapy is usually the mainstay apart from some histologies where chemotherapy may be sufficient: low-grade gliomas, desmoplastic medulloblastomas, malignant glial tumors in infants. Multidisciplinary care is best performed in tertiary care centers and should include early rehabilitation programs soon after surgery.

Distinct disease-risk groups in pediatric supratentorial and posterior fossa ependymomas

No reliable classification is in clinical use for the therapeutic stratification of children with ependymoma, such that disease risk might be identified and patients treated to ensure a combination of maximal cure rates and minimal adverse therapeutic effects. This study has examined associations between clinicopathologic and cytogenetic variables and outcome in a trial cohort of children with ependymoma, with the aim of defining a practical scheme for stratifying this heterogeneous tumor. Intracranial ependymomas (n = 146) from children treated on the RT1 trial at St. Jude Children's Research Hospital were evaluated for the status of multiple pathological features. Interphase FISH (iFISH) defined the status of loci on chromosomes 1q (EXO1), 6q (LATS1) and 9, including 9p21 (CDKN2A). Data relating to these clinicopathological and cytogenetic variables were compared with survival data in order to model disease risk groups. Extent of surgical resection was a significant determinant of outcome in both supratentorial and infratentorial compartments. Tumor cell density and mitotic count were associated with outcome among children with posterior fossa ependymomas (n = 119). Among pathologic features, only brain invasion was associated with outcome in children with supratentorial ependymomas (n = 27). For posterior fossa tumors, gain of 1q was independently associated with outcome and in combination with clinicopathological variables defined both a two-tier and three-tier system of disease risk. Among children developing posterior fossa ependymomas treated with maximal surgical resection and conformal radiotherapy, key clinicopathological variables and chromosome 1q status can be used to define tiers of disease risk. In contrast, risk factors for pediatric supratentorial tumors are limited to sub-total resection and brain invasion.

Histopathological grading of pediatric ependymoma: reproducibility and clinical relevance in European trial cohorts

Background

Histopathological grading of ependymoma has been controversial with respect to its reproducibility and clinical significance. In a 3-phase study, we reviewed the pathology of 229 intracranial ependymomas from European trial cohorts of infants (2 trials - SFOP/CNS9204) and older children (2 trials - AIEOP/CNS9904) to assess both diagnostic concordance among five neuropathologists and the prognostic utility of histopathological variables, particularly tumor grading.

Results

In phase 1, using WHO criteria and without first discussing any issue related to grading ependymomas, pathologists assessed and independently graded ependymomas from 3 of 4 trial cohorts. Diagnosis of grade II ependymoma was less frequent than grade III, a difference that increased when one cohort (CNS9204) was reassessed in phase 2, during which the pathologists discussed ependymoma grading, jointly reviewed all CNS9204 tumors, and defined a novel grading system based on the WHO classification. In phase 3, repeat independent review of two cohorts (SFOP/CNS9904) using the novel system was associated with a substantial increase in concordance on grading. Extent of tumor resection was significantly associated with progression-free survival (PFS) in SFOP and AIEOP, but not in CNS9204 and CNS9904. Strength of consensus on grade was significantly associated with PFS in only one trial cohort (AIEOP). Consensus on the scoring of individual histopathological features (necrosis, angiogenesis, cell density, and mitotic activity) correlated with PFS in AIEOP, but in no other trial.

Conclusions

We conclude that concordance on grading ependymomas can be improved by using a more prescribed scheme based on the WHO classification. Unfortunately, this appears to have utility in limited clinical settings.

Cross-species genomics matches driver mutations and cell compartments to model ependymoma

Understanding the biology that underlies histologically similar but molecularly distinct subgroups of cancer has proven difficult because their defining genetic alterations are often numerous, and the cellular origins of most cancers remain unknown. We sought to decipher this heterogeneity by integrating matched genetic alterations and candidate cells of origin to generate accurate disease models. First, we identified subgroups of human ependymoma, a form of neural tumour that arises throughout the central nervous system (CNS). Subgroup-specific alterations included amplifications and homozygous deletions of genes not yet implicated in ependymoma. To select cellular compartments most likely to give rise to subgroups of ependymoma, we matched the transcriptomes of human tumours to those of mouse neural stem cells (NSCs), isolated from different regions of the CNS at different developmental stages, with an intact or deleted Ink4a/Arf locus (that encodes Cdkn2a and b). The transcriptome of human supratentorial ependymomas with amplified EPHB2 and deleted INK4A/ARF matched only that of embryonic cerebral Ink4a/Arf(-/-) NSCs. Notably, activation of Ephb2 signalling in these, but not other, NSCs generated the first mouse model of ependymoma, which is highly penetrant and accurately models the histology and transcriptome of one subgroup of human supratentorial tumour. Further, comparative analysis of matched mouse and human tumours revealed selective deregulation in the expression and copy number of genes that control synaptogenesis, pinpointing disruption of this pathway as a critical event in the production of this ependymoma subgroup. Our data demonstrate the power of cross-species genomics to meticulously match subgroup-specific driver mutations with cellular compartments to model and interrogate cancer subgroups.

Differentiation of clear cell ependymoma of the cerebellum from hemangioblastoma by thallium-201 single photon emission computed tomography-case report-

A 57-year-old man suffered from dizziness for about one year and truncal ataxia for about one month. Magnetic resonance imaging demonstrated a cystic tumor with a homogeneously enhanced mural nodule located in the cerebellar vermis. Computed tomography angiography revealed a hypervascular nodule. These findings were compatible with hemangioblastoma. Thallium-201 single photon emission computed tomography ((201)Tl-SPECT) showed moderately high uptake in the early phase and moderately high retention in the delayed phase, whereas hemangioblastoma shows almost no retention in the delayed phase. The patient underwent total removal of the tumor. The histological diagnosis was clear cell ependymoma (CCE). CCE is a rare subtype of ependymoma, which resembles hemangioblastoma in histological and neuroimaging findings, but is considerably more aggressive. (201)Tl-SPECT can provide useful information for the preoperative differential diagnosis of infratentorial CCE and hemangioblastoma.

Chromosome 7 and 19 trisomy in cultured human neural progenitor cells

Background

Stem cell expansion and differentiation is the foundation of emerging cell therapy technologies. The potential applications of human neural progenitor cells (hNPCs) are wide ranging, but a normal cytogenetic profile is important to avoid the risk of tumor formation in clinical trials. FDA approved clinical trials are being planned and conducted for hNPC transplantation into the brain or spinal cord for various neurodegenerative disorders. Although human embryonic stem cells (hESCs) are known to show recurrent chromosomal abnormalities involving 12 and 17, no studies have revealed chromosomal abnormalities in cultured hNPCs. Therefore, we investigated frequently occurring chromosomal abnormalities in 21 independent fetal-derived hNPC lines and the possible mechanisms triggering such aberrations.

Methods and Findings

While most hNPC lines were karyotypically normal, G-band karyotyping and fluorescent in situ hybridization (FISH) analyses revealed the emergence of trisomy 7 (hNPC⁺⁷) and trisomy 19 (hNPC⁺¹⁹), in 24% and 5% of the lines, respectively. Once detected, subsequent passaging revealed emerging dominance of trisomy hNPCs. DNA microarray and immunoblotting analyses demonstrate epidermal growth factor receptor (EGFR) overexpression in hNPC⁺⁷ and hNPC⁺¹⁹ cells. We observed greater levels of telomerase (hTERT), increased proliferation (Ki67), survival (TUNEL), and neurogenesis (β_III-tubulin) in hNPC⁺⁷ and hNPC⁺¹⁹, using respective immunocytochemical markers. However, the trisomy lines underwent replicative senescence after 50–60 population doublings and never showed neoplastic changes. Although hNPC⁺⁷ and hNPC⁺¹⁹ survived better after xenotransplantation into the rat striatum, they did not form malignant tumors. Finally, EGF deprivation triggered a selection of trisomy 7 cells in a diploid hNPC line.

Conclusions

We report that hNPCs are susceptible to accumulation of chromosome 7 and 19 trisomy in long-term cell culture. These results suggest that micro-environmental cues are powerful factors in the selection of specific hNPC aneuploidies, with trisomy of chromosome 7 being the most common. Given that a number of stem cell based clinical trials are being conducted or planned in USA and a recent report in PLoS Medicine showing the dangers of grafting an inordinate number of cells, these data substantiate the need for careful cytogenetic evaluation of hNPCs (fetal or hESC-derived) before their use in clinical or basic science applications.

Expression profiling of ependymomas unravels localization and tumor grade-specific tumorigenesis

BACKGROUND

Ependymomas derive from ependymal cells that cover the cerebral ventricles and the central canal of the spinal cord. The molecular alterations leading to ependymomal oncogenesis are not completely understood.

METHODS

The authors performed array-based expression profiling on a series of 34 frozen ependymal tumors with different localizations and histologic grades. Data were analyzed by nonsupervised and supervised clustering methods along with Gene Ontology and Pathway Analyzer tools.

RESULTS

Class discovery experiments indicated a strong correlation between profiles and tumor localization as well as World Health Organization (WHO) tumor grades. On the basis of supervised clustering, intracranial ependymomas were associated with high expression levels of Notch, Hedgehog, and bone morphogenetic protein pathway members. In contrast, most of the homeobox-containing genes manifested high expression in extracranial ependymomas. The results also revealed that WHO grade 2 ependymomas differed from WHO grade 3 ependymomas by genes implicated in Wnt/beta-catenin signaling, cell cycle, E2F transcription factor 1 destruction, angiogenesis, apoptosis, remodeling of adherens junctions, and mitotic spindle formation.

CONCLUSIONS

Taken together, the tumor localization-related gene sets mainly implicated in stem cell maintenance, renewal, and differentiation suggest the dysregulation of localized cancer stem cells during ependymoma development. The WHO grade differentiating pathways suggested that alteration of the Wnt/beta-catenin signaling pathway is a key event in the tumorigenesis of WHO grade 3 ependymomas. On the basis of the current data, the authors suggest a developmental scheme of ependymomas that integrates tumor localization and tumor grades, and that pinpoints new targets for the development of future therapeutic approaches.

Classification and controversies in pathology of ependymomas

PURPOSE

Bailey and Cushing established ependymoma as a brain tumour entity in the first brain tumour classification (1926). Diagnosis of ependymomas is not subject to controversy as long as other tumours presenting ependymoma-like features have been ruled out. Grading conversely is a source of debate. Description of histological features establishing diagnosis and grading of ependymomas may help to better understand this controversy.

METHODS

Literature has been reviewed using PubMed with the following key words: ependymoma, +/- prognosis, +/- biomaker, +/- grading, +/- immunohistochemistry, +/- proliferative index.

RESULTS

Grading controversy arises from elusive WHO features and individual characteristics of ependymomas including tumour location, tumour pattern/variant and variable expression of biomarkers.

CONCLUSION

There is a need for a grading scheme with a proven general ability to dissociate grades, and to predict individual clinical evolution. Only then will stratified and targeted therapeutics for ependymal tumours be possible.

EDG3 and SHC3 on chromosome 9q22 are co-amplified in human ependymomas

By qPCR we found that EDG3 and SHC3 were amplified in 60% of ependymomas but none in choroid plexus papillomas. In ependymomas EDG3 and SHC3 amplification increased Shc3 protein levels while EDG3 was less affected. Both proteins were co-immunoprecipitated from ependymoma and Shc3 was tyrosine phosphorylated thus presumably active. We showed by digestion with N-glycosidase-F that EDG3 was glycosylated indicating that EDG3 protein was not retained in the endoplasmic reticulum. The co-immunoprecipitation of Shc3 and EDG3 proteins from ependymomas with amplification of SHC3 and EDG3 genes suggests that the two proteins co-operate and are important for ependymomas in vivo.

Chordoid glioma: a case report and molecular characterization of five cases

Chordoid gliomas are rare, slow-growing neoplasms of the anterior third ventricle. We reported a case of chordoid glioma in a 41-year-old man with obstructive hydrocephalus. Histologically, the tumor consisted of polygonal epithelioid cells admixed with elongated cells in a myxoid stroma. A prominent lymphoplasmacytic infiltrate was present. The tumor cells expressed glial fibrillary acidic protein (GFAP), epithelial membrane antigen (EMA), vimentin, CD31, CD34, epidermal growth factor receptor (EGFR) and S100 but were negative for pankeratin and E-cadherin. The percentage of Ki67 positive cells was approximately 3%. Weak p53 immunoreactivity was seen in less than 10% of the cells. Array comparative genomic hybridization performed on this case, as well as on four other archived cases, showed losses at several loci. Fluorescence in situ hybridization (FISH) confirmed consistent genetic alterations at 9p21 and 11q13. These are the fifth through ninth reported cases of chordoid gliomas with molecular characterization suggesting a distinct genetic origin from other gliomas.