[Supratentorial neuroepithelial tumor with PLAGL1 gene fusion - a new type of morphologically variable pediatric brain neoplasm defined by a distinct DNA methylation class. A case report and literature review]. / Supratentorial'naya neiroepitelial'naya opukhol' so sliyaniem gena PLAGL1 u detei ­ novyi tip opukholi mozga s raznoobraznoi morfologicheskoi kartinoi i otlichitel'nym metilyatsionnym profilem(sluchai iz praktiki i obzor literatury).

BACKGROUND: Methylation analysis has become a powerful diagnostic tool in modern neurooncology. This technique is valuable to diagnose new brain tumor types. OBJECTIVE: To describe the MRI and histological pattern of neuroepithelial tumor with PLAGL1 gene fusion. MATERIAL AND METHODS: We present a 6-year-old patient with small right frontal intraaxial tumor causing drug resistant epilepsy. Despite indolent preoperative clinical course and MRI features suggesting glioneuronal tumor, histological evaluation revealed characteristics of high-grade glioma, ependymoma and neuroblastoma. RESULTS: Methylation analysis of tumor DNA confirmed a new type of a recently discovered neoplasm - neuroepithelial tumor with PLAGL1 fusion (NET PLAGL1). PCR confirmed fusion of PLAGL1 and EWSR1 genes. No seizures were observed throughout the follow-up period. There was no tumor relapse a year after surgery. CONCLUSION: Methylation analysis in neurooncology is essential for unclear tumor morphology or divergence between histological and clinical data. In our case, this technique confirmed benign nature of tumor, and we preferred follow-up without unnecessary adjuvant treatment.

Supramaximal resection based on en-bloc technique reduces tumor burden and prolongs survival in primary supratentorial lobar glioblastoma.

PURPOSE: Resection beyond the contrast-enhanced zone contributed to reduce tumor burden and prolong survival in glioblastomas. The optimal extent of resection (EOR) and how to achieve it are worthy of continuous investigation for obtaining a satisfactory balance between maximal resection and the preservation of neurological function. METHODS: A total of 340 adult supratentorial lobar glioblastomas (included astrocytoma, WHO 4, IDH mutation and glioblastoma) were retrospectively evaluated. The clinical data, EOR, technique of resection, postoperative complications, overall survival (OS) and progression-free survival (PFS) were assessed by univariate, multivariate and propensity score matched analysis. Histological staining was performed to comprehend the effect of the membranous structures and the cell distribution in tumoral and peritumoral regions. RESULTS: Supramaximal resection (SMR) was confirmed as resection with 100% EORCE and > 50% EORnCE in glioblastomas by Cox proportional hazards model. Histological results showed SMR reduced the cell density of surgical edge compared to total resection. En-bloc technique based on membranous structures, which had blocking effect on tumoral invasion, contributed to achieve SMR. Moreover, applying en-bloc technique and achieving SMR did not additionally deteriorate neurological function and had similarly effects on the improvement of neurological function. Multivariate analysis confirmed that IDH1 status, technique of resection and EOR were independently correlated with PFS, and > 64 years old, IDH1 status, technique of resection, EOR and preoperative NIHSS were independently correlated with OS. CONCLUSIONS: Applying en-bloc technique and achieving SMR, which could reduce tumor burden and did not increase additional complications, both had remarkedly positive effects on clinical outcomes in patients with primary supratentorial lobar glioblastomas.

[Verification of the diagnosis of supratentorial ependymomas by real-time PCR]. / Verifikatsiya diagnoza supratentorial'nykh ependimom metodom PTsR v rezhime real'nogo vremeni.

BACKGROUND: Differential diagnosis of supratentorial ependymomas is of particular difficulty in neurooncology due to nonspecific clinical and radiographic findings, a rare seen «classic¼ morphological picture, and a nonspecific immunophenotype. Thanks to molecular genetic methods, in particular real-time PCR, it has become possible to verify supratentorial ependymomas and identify their molecular group, on which further prognosis depends. OBJECTIVE: To develop a set of molecular genetic tests based on real-time PCR to verify supratentorial ependymomas. MATERIAL AND METHODS: 56 tissue samples were collected from patients with supratentorial ependymomas, WHO Grade II, and anaplastic ependymomas, WHO Grade III. We developed primers and fluorescent TaqMan probes for real-time PCR analysis to detect the ZFTA::RELA, ZFTA::MAML2, ZFTA::NCOA2, ZFTA::MAML3, YAP1::MAMLD1, and YAP1::FAM118B gene fusions. For immunohistochemical analysis, monoclonal rabbit anti-NF-kb p65 antibodies (HUABIO, China) were used, the study was carried out on AutostainerLink 48 immunostainer (DAKO, Denmark). RESULTS: Real-time PCR was able to verify the diagnosis for 69.9% (n=39) of samples and classify them into molecular groups of ZFTA- or YAP1-positive supratentorial ependymomas. Immunohistochemically it was possible to verify 58% (n=29) ependymomas. CONCLUSION: Diagnosis by real-time PCR is a relatively fast, accessible and easily interpreted method that allows verification of the molecular group in 70% of cases of supratentorial ependymomas without the use of additional methods.

Clinical and genomic differences in supratentorial versus infratentorial NF2 mutant meningiomas.

OBJECTIVE: Mutations in NF2 are the most common somatic driver mutation in sporadic meningiomas. NF2 mutant meningiomas preferentially arise along the cerebral convexities-however, they can also be found in the posterior fossa. The authors investigated whether NF2 mutant meningiomas differ in clinical and genomic features based on their location relative to the tentorium. METHODS: Clinical and whole exome sequencing (WES) data for patients who underwent resection of sporadic NF2 mutant meningiomas were reviewed and analyzed. RESULTS: A total of 191 NF2 mutant meningiomas were included (165 supratentorial, 26 infratentorial). Supratentorial NF2 mutant meningiomas were significantly associated with edema (64.0% vs 28.0%, p < 0.001); higher grade-i.e., WHO grade II or III (41.8% vs 3.9%, p < 0.001); elevated Ki-67 (55.0% vs 13.6%, p < 0.001); and larger volume (mean 45.5 cm3 vs 14.9 cm3, p < 0.001). Furthermore, supratentorial tumors were more likely to harbor the higher-risk feature of chromosome 1p deletion (p = 0.038) and had a larger fraction of the genome altered with loss of heterozygosity (p < 0.001). Infratentorial meningiomas were more likely to undergo subtotal resection than supratentorial tumors (37.5% vs 15.8%, p = 0.021); however, there was no significant difference in overall (p = 0.2) or progression-free (p = 0.4) survival. CONCLUSIONS: Supratentorial NF2 mutant meningiomas are associated with more aggressive clinical and genomic features as compared with their infratentorial counterparts. Although infratentorial tumors have higher rates of subtotal resection, there is no associated difference in survival or recurrence. These findings help to better inform surgical decision-making in the management of NF2 mutant meningiomas based on location, and may guide postoperative management of these tumors.

Overview of recent advances in the classification of ependymomas in WHO CNS5 classification: Simplified approach to their integrated diagnosis.

Ependymomas can arise along the entire neuraxis; however, they possess site-specific unique molecular alterations and a methylome pattern which is directly related with the prognostic outcomes. Since 2016, when the updated fourth edition of World Health Organization (WHO) classification of tumors of the central nervous system was published, it has been emphasized to classify ependymomas by anatomic site and molecular signatures associated genetic alterations so that classification of the disease reflects its underlying biology. In continuation, the fifth edition of the WHO classification of CNS tumors introduces major changes, including site-specific molecular profiles as the basis of classifying ependymomas. Furthermore, an integrated tier system of reporting is recommended for better clinical correlation and predicting outcomes. WHO grading can still be included in a specific tier, along with molecular markers.

ZFTA (Zinc Finger Translocation Associated) Fusion in Supratentorial Ependymomas: Low Prevalence in South Asians and No Correlation with Survival.

BACKGROUND: Supratentorial ependymomas (STEs) are an aggressive group of ependymomas, topographically distinct from their posterior fossa and spinal counterparts. Zinc finger translocation associated (ZFTA) fusion-positive cases have been reported to account for the majority of STEs, although data on its association with poorer outcomes are inconsistent. MATERIALS AND METHODS: We assessed the prevalence of the ZFTA fusion by reverse-transcription polymerase chain reaction and fluorescence in situ hybridization in a cohort of 61 patients (68 samples) with STE. Our primary outcome was to determine the role of the ZFTA fusion on progression-free and overall survival of patients with STE. Our secondary objectives were to assess the impact of ZFTA fusion on nuclear factor (NF)-kB pathway signaling via surrogate markers of this pathway, namely COX-2, CCND1, and L1 cell adhesion molecule. RESULTS: ZFTA fusion was noted in 21.3% of STEs in our cohort. The presence of this rearrangement did not significantly impact the progression-free or overall survival of patients with STEs and was not associated with upregulation of markers of the NF-kB pathway. Only gross total resection was significantly associated with better progression-free survival. CONCLUSIONS: In contradiction to previous reports from across the world, the ZFTA fusion is far less prevalent among our population. It does not appear to drive NF-kB signaling or significantly affect outcomes. Gross total resection must be attempted in all cases of STE and adjuvant radiation and/or chemotherapy employed when gross total resection is not achieved.

Updates in the classification of ependymal neoplasms: The 2021 WHO Classification and beyond.

Ependymal neoplasms occur at all ages and encompass multiple tumor types and subtypes that develop in the supratentorial compartment, the posterior fossa, or the spinal cord. Clinically, ependymomas represent a very heterogeneous group of tumors from rather benign subependymomas to very aggressive and often deadly childhood ependymomas of the posterior fossa. Newly identified biological markers and classification schemes, e. g. based on global DNA methylation profiling, have led to the definition of 10 types of ependymal tumors and an improved prediction of patients' outcome by applying the new classification system. While the exact genetic basis for several ependymoma types still remains unclear, the knowledge about ependymoma driving events has significantly increased within the last decade and contributed to a classification based on molecular characteristics and localization rather than histological features alone. Convincing evidence is now pointing towards gene fusions involving ZFTA or YAP1 causing the development of supratentorial ependymomas. Also, H3, EZHIP, or TERT mutations have been detected in a fraction of infratentorial ependymal tumors. Finally, MYCN amplifications have recently been identified in spinal ependymomas, in addition to the previously known mutations in NF2. This review summarizes how recent findings regarding biology, molecular tumor typing, and clinical outcome have impacted the classification of ependymomas as suggested by the updated 2021 WHO CNS tumor classification system. We focus on changes compared to the previous classification of 2016 and discuss how a formal grading could evolve in the future and guide clinicians to treat ependymoma patients.

Recurrent fusions in PLAGL1 define a distinct subset of pediatric-type supratentorial neuroepithelial tumors.

Ependymomas encompass a heterogeneous group of central nervous system (CNS) neoplasms that occur along the entire neuroaxis. In recent years, extensive (epi-)genomic profiling efforts have identified several molecular groups of ependymoma that are characterized by distinct molecular alterations and/or patterns. Based on unsupervised visualization of a large cohort of genome-wide DNA methylation data, we identified a highly distinct group of pediatric-type tumors (n = 40) forming a cluster separate from all established CNS tumor types, of which a high proportion were histopathologically diagnosed as ependymoma. RNA sequencing revealed recurrent fusions involving the pleomorphic adenoma gene-like 1 (PLAGL1) gene in 19 of 20 of the samples analyzed, with the most common fusion being EWSR1:PLAGL1 (n = 13). Five tumors showed a PLAGL1:FOXO1 fusion and one a PLAGL1:EP300 fusion. High transcript levels of PLAGL1 were noted in these tumors, with concurrent overexpression of the imprinted genes H19 and IGF2, which are regulated by PLAGL1. Histopathological review of cases with sufficient material (n = 16) demonstrated a broad morphological spectrum of tumors with predominant ependymoma-like features. Immunohistochemically, tumors were GFAP positive and OLIG2- and SOX10 negative. In 3/16 of the cases, a dot-like positivity for EMA was detected. All tumors in our series were located in the supratentorial compartment. Median age of the patients at the time of diagnosis was 6.2 years. Median progression-free survival was 35 months (for 11 patients with data available). In summary, our findings suggest the existence of a novel group of supratentorial neuroepithelial tumors that are characterized by recurrent PLAGL1 fusions and enriched for pediatric patients.

Supratentorial non-RELA, ZFTA-fused ependymomas: a comprehensive phenotype genotype correlation highlighting the number of zinc fingers in ZFTA-NCOA1/2 fusions.

The cIMPACT-NOW Update 7 has replaced the WHO nosology of "ependymoma, RELA fusion positive" by "Supratentorial-ependymoma, C11orf95-fusion positive". This modification reinforces the idea that supratentorial-ependymomas exhibiting fusion that implicates the C11orf95 (now called ZFTA) gene with or without the RELA gene, represent the same histomolecular entity. A hot off the press molecular study has identified distinct clusters of the DNA methylation class of ZFTA fusion-positive tumors. Interestingly, clusters 2 and 4 comprised tumors of different morphologies, with various ZFTA fusions without involvement of RELA. In this paper, we present a detailed series of thirteen cases of non-RELA ZFTA-fused supratentorial tumors with extensive clinical, radiological, histopathological, immunohistochemical, genetic and epigenetic (DNA methylation profiling) characterization. Contrary to the age of onset and MRI aspects similar to RELA fusion-positive EPN, we noted significant histopathological heterogeneity (pleomorphic xanthoastrocytoma-like, astroblastoma-like, ependymoma-like, and even sarcoma-like patterns) in this cohort. Immunophenotypically, these NFκB immunonegative tumors expressed GFAP variably, but EMA constantly and L1CAM frequently. Different gene partners were fused with ZFTA: NCOA1/2, MAML2 and for the first time MN1. These tumors had epigenetic homologies within the DNA methylation class of ependymomas-RELA and were classified as satellite clusters 2 and 4. Cluster 2 (n = 9) corresponded to tumors with classic ependymal histological features (n = 4) but also had astroblastic features (n = 5). Various types of ZFTA fusions were associated with cluster 2, but as in the original report, ZFTA:MAML2 fusion was frequent. Cluster 4 was enriched with sarcoma-like tumors. Moreover, we reported a novel anatomy of three ZFTA:NCOA1/2 fusions with only 1 ZFTA zinc finger domain in the putative fusion protein, whereas all previously reported non-RELA ZFTA fusions have 4 ZFTA zinc fingers. All three cases presented a sarcoma-like morphology. This genotype/phenotype association requires further studies for confirmation. Our series is the first to extensively characterize this new subset of supratentorial ZFTA-fused ependymomas and highlights the usefulness of ZFTA FISH analysis to confirm the existence of a rearrangement without RELA abnormality.

Transcriptional profiling of paediatric ependymomas identifies prognostically significant groups.

The majority of supratentorial ependymomas in children contain oncogenic fusions, such as ZFTA-RELA or YAP1-MAMLD1. In contrast, posterior fossa (PF) ependymomas lack recurrent somatic mutations and are classified based on gene expression or methylation profiling into group A (PFA) and group B (PFB). We have applied a novel method, NanoString nCounter Technology, to identify four molecular groups among 16 supratentorial and 50 PF paediatric ependymomas, using 4-5 group-specific signature genes. Clustering analysis of 16 supratentorial ependymomas revealed 9 tumours with a RELA fusion-positive signature (RELA+), 1 tumour with a YAP1 fusion-positive signature (YAP1+), and 6 not-classified tumours. Additionally, we identified one RELA+ tumour among historically diagnosed CNS primitive neuroectodermal tumour samples. Overall, 9 of 10 tumours with the RELA+ signature possessed the ZFTA-RELA fusion as detected by next-generation sequencing (p = 0.005). Similarly, the only tumour with a YAP1+ signature exhibited the YAP1-MAMLD1 fusion. Among the remaining unclassified ependymomas, which did not exhibit the ZFTA-RELA fusion, the ZFTA-MAML2 fusion was detected in one case. Notably, among nine ependymoma patients with the RELA+ signature, eight survived at least 5 years after diagnosis. Clustering analysis of PF tumours revealed 42 samples with PFA signatures and 7 samples with PFB signatures. Clinical characteristics of patients with PFA and PFB ependymomas corroborated the previous findings. In conclusion, we confirm here that the NanoString method is a useful single tool for the diagnosis of all four main molecular groups of ependymoma. The differences in reported survival rates warrant further clinical investigation of patients with the ZFTA-RELA fusion.

Cross-Species Genomics Reveals Oncogenic Dependencies in ZFTA/C11orf95 Fusion-Positive Supratentorial Ependymomas.

Molecular groups of supratentorial ependymomas comprise tumors with ZFTA-RELA or YAP1-involving fusions and fusion-negative subependymoma. However, occasionally supratentorial ependymomas cannot be readily assigned to any of these groups due to lack of detection of a typical fusion and/or ambiguous DNA methylation-based classification. An unbiased approach with a cohort of unprecedented size revealed distinct methylation clusters composed of tumors with ependymal but also various other histologic features containing alternative translocations that shared ZFTA as a partner gene. Somatic overexpression of ZFTA-associated fusion genes in the developing cerebral cortex is capable of inducing tumor formation in vivo, and cross-species comparative analyses identified GLI2 as a key downstream regulator of tumorigenesis in all tumors. Targeting GLI2 with arsenic trioxide caused extended survival of tumor-bearing animals, indicating a potential therapeutic vulnerability in ZFTA fusion-positive tumors. SIGNIFICANCE: ZFTA-RELA fusions are a hallmark feature of supratentorial ependymoma. We find that ZFTA acts as a partner for alternative transcriptional activators in oncogenic fusions of supratentorial tumors with various histologic characteristics. Establishing representative mouse models, we identify potential therapeutic targets shared by ZFTA fusion-positive tumors, such as GLI2.This article is highlighted in the In This Issue feature, p. 2113.

ZFTA Translocations Constitute Ependymoma Chromatin Remodeling and Transcription Factors.

ZFTA (C11orf95)-a gene of unknown function-partners with a variety of transcriptional coactivators in translocations that drive supratentorial ependymoma, a frequently lethal brain tumor. Understanding the function of ZFTA is key to developing therapies that inhibit these fusion proteins. Here, using a combination of transcriptomics, chromatin immunoprecipitation sequencing, and proteomics, we interrogated a series of deletion-mutant genes to identify a tripartite transformation mechanism of ZFTA-containing fusions, including: spontaneous nuclear translocation, extensive chromatin binding, and SWI/SNF, SAGA, and NuA4/Tip60 HAT chromatin modifier complex recruitment. Thereby, ZFTA tethers fusion proteins across the genome, modifying chromatin to an active state and enabling its partner transcriptional coactivators to promote promiscuous expression of a transforming transcriptome. Using mouse models, we validate further those elements of ZFTA-fusion proteins that are critical for transformation-including ZFTA zinc fingers and partner gene transactivation domains-thereby unmasking vulnerabilities for therapeutic targeting. SIGNIFICANCE: Ependymomas are hard-to-treat brain tumors driven by translocations between ZFTA and a variety of transcriptional coactivators. We dissect the transforming mechanism of these fusion proteins and identify protein domains indispensable for tumorigenesis, thereby providing insights into the molecular basis of ependymoma tumorigenesis and vulnerabilities for therapeutic targeting.This article is highlighted in the In This Issue feature, p. 2113.

ZFTA-RELA Dictates Oncogenic Transcriptional Programs to Drive Aggressive Supratentorial Ependymoma.

More than 60% of supratentorial ependymomas harbor a ZFTA-RELA (ZRfus) gene fusion (formerly C11orf95-RELA). To study the biology of ZRfus, we developed an autochthonous mouse tumor model using in utero electroporation (IUE) of the embryonic mouse brain. Integrative epigenomic and transcriptomic mapping was performed on IUE-driven ZRfus tumors by CUT&RUN, chromatin immunoprecipitation sequencing, assay for transposase-accessible chromatin sequencing, and RNA sequencing and compared with human ZRfus-driven ependymoma. In addition to direct canonical NFκB pathway activation, ZRfus dictates a neoplastic transcriptional program and binds to thousands of unique sites across the genome that are enriched with PLAGL family transcription factor (TF) motifs. ZRfus activates gene expression programs through recruitment of transcriptional coactivators (Brd4, Ep300, Cbp, Pol2) that are amenable to pharmacologic inhibition. Downstream ZRfus target genes converge on developmental programs marked by PLAGL TF proteins, and activate neoplastic programs enriched in Mapk, focal adhesion, and gene imprinting networks. SIGNIFICANCE: Ependymomas are aggressive brain tumors. Although drivers of supratentorial ependymoma (ZFTA- and YAP1-associated gene fusions) have been discovered, their functions remain unclear. Our study investigates the biology of ZFTA-RELA-driven ependymoma, specifically mechanisms of transcriptional deregulation and direct downstream gene networks that may be leveraged for potential therapeutic testing.This article is highlighted in the In This Issue feature, p. 2113.

C11orf95-RELA fusion drives aberrant gene expression through the unique epigenetic regulation for ependymoma formation.

Recurrent C11orf95-RELA fusions (RELAFUS) are the hallmark of supratentorial ependymomas. The presence of RELA as the fusion partner indicates a close association of aberrant NF-κB activity with tumorigenesis. However, the oncogenic role of the C11orf95 has not been determined. Here, we performed ChIP-seq analyses to explore genomic regions bound by RELAFUS and H3K27ac proteins in human 293T and mouse ependymoma cells. We then utilized published RNA-Seq data from human and mouse RELAFUS tumors and identified target genes that were directly regulated by RELAFUS in these tumors. Subsequent transcription factor motif analyses of RELAFUS target genes detected a unique GC-rich motif recognized by the C11orf95 moiety, that is present in approximately half of RELAFUS target genes. Luciferase assays confirmed that a promoter carrying this motif is sufficient to drive RELAFUS-dependent gene expression. Further, the RELAFUS target genes were found to be overlapped with Rela target genes primarily via non-canonical NF-κB binding sites. Using a series of truncation and substitution mutants of RELAFUS, we also show that the activation domain in the RELAFUS moiety is necessary for the regulation of gene expression of these RELAFUS target genes. Lastly, we performed an anti-cancer drug screening with mouse ependymoma cells and identified potential anti-ependymoma drugs that are related to the oncogenic mechanism of RELAFUS. These findings suggested that RELAFUS might induce ependymoma formation through oncogenic pathways orchestrated by both C11orf95 and RELA target genes. Thus, our study unveils a complex gene function of RELAFUS as an oncogenic transcription factor in RELAFUS positive ependymomas.

Ependymoma-like tumor with mesenchymal differentiation harboring C11orf95-NCOA1/2 or -RELA fusion: A hitherto unclassified tumor related to ependymoma.

Recurrent fusion genes involving C11orf95, C11orf95-RELA, have been identified only in supratentorial ependymomas among primary CNS tumors. Here, we report hitherto histopathologically unclassifiable high-grade tumors, under the tentative label of "ependymoma-like tumors with mesenchymal differentiation (ELTMDs)," harboring C11orf95-NCOA1/2 or -RELA fusion. We examined the clinicopathological and molecular features in five cases of ELTMDs. Except for one adult case (50 years old), all cases were in children ranging from 1 to 2.5 years old. All patients presented with a mass lesion in the cerebral hemisphere. Histologically, all cases demonstrated a similar histology with a mixture of components. The major components were embryonal-appearing components forming well-delineated tumor cell nests composed of small uniform cells with high proliferative activity, and spindle-cell mesenchymal components with a low- to high-grade sarcoma-like appearance. The embryonal-appearing components exhibited minimal ependymal differentiation including a characteristic EMA positivity and tubular structures, but histologically did not fit with ependymoma because they lacked perivascular pseudorosettes, a histological hallmark of ependymoma, formed well-delineated nests, and had diffuse and strong staining for CAM5.2. Molecular analysis identified C11orf95-NCOA1, -NCOA2, and -RELA in two, one, and two cases, respectively. t-distributed stochastic neighbor embedding analysis of DNA methylation data from two cases with C11orf95-NCOA1 or -NCOA2 and a reference set of 380 CNS tumors revealed that these two cases were clustered together and were distinct from all subgroups of ependymomas. In conclusion, although ELTMDs exhibited morphological and genetic associations with supratentorial ependymoma with C11orf95-RELA, they cannot be regarded as ependymoma. Further analyses of more cases are needed to clarify their differences and similarities.

Supratentorial ependymoma in childhood: more than just RELA or YAP.

Two distinct genetically defined entities of ependymoma arising in the supratentorial compartment are characterized by the presence of either a C11orf95-RELA or a YAP-MAMLD1 fusion, respectively. There is growing evidence that supratentorial ependymomas without these genetic features exist. In this study, we report on 18 pediatric non-RELA/non-YAP supratentorial ependymomas that were systematically characterized by means of their histology, immunophenotype, genetics, and epigenomics. Comprehensive molecular analyses included high-resolution copy number analysis, methylation profiling, analysis of fusion transcripts by Nanostring technology, and RNA sequencing. Based upon histological and immunohistochemical features two main patterns were identified-RELA-like (n = 9) and tanycytic ependymomas (n = 6). In the RELA-like group histologically assigned to WHO grade III and resembling RELA-fused ependymomas, tumors lacked nuclear expression of p65-RelA as a surrogate marker for a pathological activation of the NF-κB pathway. Three tumors showed alternative C11orf95 fusions to MAML2 or NCOA1. A methylation-based brain tumor classifier assigned two RELA-like tumors to the methylation class "EP, RELA-fusion"; the others demonstrated no significant similarity score. Of the tanycytic group, 5/6 tumors were assigned a WHO grade II. No gene fusions were detected. Methylation profiling did not show any association with an established methylation class. We additionally identified two astroblastoma-like tumors that both presented with chromothripsis of chromosome 22 but lacked MN1 breaks according to FISH analysis. They revealed novel fusion events involving genes in chromosome 22. One further tumor with polyploid cytogenetics was interpreted as PFB ependymoma by the brain tumor methylation classifier but had no relation to the posterior fossa. Clinical follow-up was available for 16/18 patients. Patients with tanycytic and astroblastoma-like tumors had no relapse, while 2 patients with RELA-like ependymomas died. Our data indicate that in addition to ependymomas discovered so far, at least two more supratentorial ependymoma types (RELA-like and tanycytic) exist.

Supratentorial ependymoma with YAP1:FAM118B fusion: A case report.

We report a case of a 26-year-old Chinese man who had experienced three grand mal seizures in the past two months. Magnetic resonance imaging revealed a relatively well-circumscribed lesion in the left frontal lobe. A craniotomy with total excision of the tumor was performed. Histopathological investigations confirmed a grade 2 ependymoma according to the World Health Organization classification. Genetic analysis revealed a tumor harboring FAM118B fusion to YAP1, and no other genetic alterations or methylation of the O6 -methylguanine-DNA methyltransferase gene promoter were detected. This is the second case report of ependymoma with YAP1:FAM118B fusion.

Ependymoma with C11orf95-MAML2 fusion: presenting with granular cell and ganglion cell features.

C11orf95-RELA fusion or, less frequently, YAP1 fusion is recurrently detected in most cases of supratentorial ependymoma. Other fusions have rarely been reported in some cases of supratentorial ependymoma, and little is known about their pathological or clinical features. Here, we present a case of supratentorial ependymoma with unusual pathological findings and C11orf95-MAML2 fusion. A 23-year-old man was admitted to our hospital because of headache and vomiting. Magnetic resonance imaging revealed a cystic lesion in the right frontal lobe, and gross total resection of the tumor was performed. Pathologically, the tumor was mainly composed of typical ependymal lesions with perivascular pseudorosettes and contained some atypical lesions, with granular and ganglion cell features. The tumor was diagnosed as anaplastic ependymoma, which was classified as grade III on the World Health Organization scale, and found to be RELA fusion-positive in the DNA methylation analysis. However, the tumor was negative for C11orf95-RELA fusion, and RNA sequencing detected C11orf95-MAML2 fusion. The patient has not received adjuvant therapy and has remained alive without any evidence of disease for 30 months, suggesting that the prognosis might be better than that of typical C11orf95-RELA fusion-positive ependymoma.