Spinal Cord Ependymomas With MYCN Amplification Show Aggressive Clinical Behavior

Specifics of spinal neuropathology in the molecular age

Tumors located in the spinal cord and its coverings can be diagnostically challenging and require special consideration regarding treatment options. During the last decade, important advances regarding the molecular characterization of central and peripheral nervous system tumors were achieved, resulting in improved diagnostic precision, and understanding of the tumor spectrum of this compartment. In particular, array-based global DNA methylation profiling has emerged as a valuable tool to delineate biologically and clinically relevant tumor subgroups and has been incorporated in the current WHO classification for central nervous system tumors of 2021. In addition, several genetic drivers have been described, which may also help to define distinct tumor types and subtypes. Importantly, the current molecular understanding not only sharpens diagnostic precision but also provides the opportunity to investigate both targeted therapies as well as risk-adapted changes in treatment intensity. Here, we discuss the current knowledge and the clinical relevance of molecular neuropathology in spinal tumor entities.

A comprehensive evaluation of imaging features in pediatric spinal gliomas and their value in predicting tumor grade and histology

PURPOSE

Pediatric spinal cord gliomas (PSGs) are rare in children and few reports detail their imaging features. We tested the association of tumoral grade with imaging features and proposed a novel approach to categorize post-contrast enhancement patterns in PSGs.

METHODS

This single-center, retrospective study included patients <21 years of age with preoperative spinal MRI and confirmed pathological diagnosis of PSG from 2000-2022. Tumors were classified using the 5th edition of the WHO CNS Tumors Classification. Two radiologists reviewed multiple imaging features, and classified enhancement patterns using a novel approach. Fisher's exact test determined associations between imaging and histological features.

RESULTS

Forty-one PSGs were reviewed. Thirty-four were intramedullary, and seven were extramedullary. Pilocytic astrocytoma was the most common tumor (39.02%). Pain and weakness were the most prevalent symptoms. Seven patients (17.07%) died. Cyst, syringomyelia, and leptomeningeal enhancement were associated with tumor grade. Widening of the spinal canal was observed only in low-grade astrocytomas. There was a significant association between tumor grade and contrast enhancement pattern. Specifically, low-grade PSGs were more likely to exhibit type 1A enhancement (mass-like, with well-defined enhancing margins) and less likely to exhibit type 1B enhancement (mass-like, with ill-defined enhancing margins).

CONCLUSION

PSGs display overlapping imaging features, making grade differentiation challenging based solely on imaging. The correlation between tumor grade and contrast enhancement patterns suggests a potential diagnostic avenue, requiring further validation with larger, multicenter studies. Furthermore, Low-grade PSGs display cysts and syringomyelia more frequently, and leptomeningeal enhancement is less common.

MYCN immunohistochemistry as surrogate marker for MYCN-amplified spinal ependymomas

MYCN (master regulator of cell cycle entry and proliferative metabolism) gene amplification defines a molecular subgroup of spinal cord ependymomas that show high-grade morphology and aggressive behavior. Demonstration of MYCN amplification by DNA methylation or fluorescence-in situ hybridization (FISH) is required for diagnosis. We aimed to (i) assess prevalence and clinicopathological features of MYCN-amplified spinal ependymomas and (ii) evaluate utility of immunohistochemistry (IHC) for MYCN protein as a surrogate for molecular testing. A combined retrospective-prospective study spanning 8 years was designed during which all spinal cord ependymomas with adequate tissue were subjected to MYCN FISH and MYCN IHC. Among 77 spinal cord ependymomas included, MYCN amplification was identified in 4 samples from 3 patients (3/74, 4%) including two (1st and 2nd recurrences) from the same patient. All patients were adults (median age at diagnosis of 32 years) including two females and one male. The index tumors were located in thoracic (n = 2) and lumbar (n = 1) spinal cord. One of the female patients had neurofibromatosis type 2 (NF2). All four tumors showed anaplastic histology. Diffuse expression of MYCN protein was seen in all four MYCN-amplified samples but in none of the non-amplified cases, thus showing 100% concordance with FISH results. On follow-up, the NF2 patient developed widespread spinal dissemination while another developed recurrence proximal to the site of previous excision. To conclude, MYCN-amplified spinal ependymomas are rare tumors, accounting for ~ 4% of spinal cord ependymomas. Within the limitation of small sample size, MYCN IHC showed excellent concordance with MYCN gene amplification.

Pediatric CNS tumors and 2021 WHO classification: what do oncologists need from pathologists?

The fifth edition of the WHO Classification of Tumors of the Central Nervous System (CNS), published in 2021, established new approaches to both CNS tumor nomenclature and grading, emphasizing the importance of integrated diagnoses and layered reports. This edition increased the role of molecular diagnostics in CNS tumor classification while still relying on other established approaches such as histology and immunohistochemistry. Moreover, it introduced new tumor types and subtypes based on novel diagnostic technologies such as DNA methylome profiling. Over the past decade, molecular techniques identified numerous key genetic alterations in CSN tumors, with important implications regarding the understanding of pathogenesis but also for prognosis and the development and application of effective molecularly targeted therapies. This review summarizes the major changes in the 2021 fifth edition classification of pediatric CNS tumors, highlighting for each entity the molecular alterations and other information that are relevant for diagnostic, prognostic, or therapeutic purposes and that patients' and oncologists' need from a pathology report.

Prognostic and predictive biomarkers in central nervous system tumours: the molecular state of play

Central nervous system (CNS) tumours were one of the first cancer types to adopt and integrate molecular profiling into routine clinical diagnosis in 2016. The vast majority of these biomarkers, used to discriminate between tumour types, also offered prognostic information. With the advent of The Cancer Genome Atlas (TCGA) and other large genomic datasets, further prognostic sub-stratification was possible within tumour types, leading to increased precision in CNS tumour grading. This review outlines the evolution of the molecular landscape of adult CNS tumours, through the prism of World Health Organization (WHO) Classifications. We begin our journey in the pre-molecular era, where high-grade gliomas were divided into 'primary' and 'secondary' glioblastomas. Molecular alterations explaining these clinicopathological observations were the first branching points of glioma diagnostics, with the discovery of IDH1/2 mutations and 1p/19q codeletion. Subsequently, the rigorous characterisation of paediatric gliomas led to the unearthing of histone H3 alterations as a key event in gliomagenesis, which also had implications for young adult patients. Simultaneously, studies investigating prognostic biomarkers within tumour types were undertaken. Certain genomic phenotypes were found to portend unfavourable outcomes, for example, MYCN amplification in spinal ependymoma. The arrival of methylation profiling, having revolutionised the diagnosis of CNS tumours, now promises to bring increased prognostic accuracy, as has been shown in meningiomas. While MGMT promoter hypermethylation has remained a reliable biomarker of response to cytotoxic chemotherapy, targeted therapy in CNS tumours has unfortunately not had the success of other cancers. Therefore, predictive biomarkers have lagged behind the identification of prognostic biomarkers in CNS tumours. Emerging research from new clinical trials is cause for guarded optimism and may shift our conceptualisation of predictive biomarker testing in CNS tumours.

Ependymoma from Benign to Highly Aggressive Diseases: A Review

Ependymomas comprise biologically distinct tumor types with respect to age distribution, (epi)genetics, localization, and prognosis. Multimodal risk-stratification, including histopathological and molecular features, is essential in these biologically defined tumor types. Gross total resection (GTR), achieved with intraoperative monitoring and neuronavigation, and if necessary, second-look surgery, is the most effective treatment. Adjuvant radiation therapy is mandatory in high-risk tumors and in case of residual tumor. There is yet growing evidence that some ependymal tumors may be cured by surgery alone. To date, the role of chemotherapy is unclear and subject of current studies.Even though standard therapy can achieve reasonable survival rates for the majority of ependymoma patients, long-term follow-up still reveals a high probability of relapse in certain biological entities.With increasing knowledge of biologically distinct tumor types, risk-adapted adjuvant therapy gains importance. Beyond initial tumor control, and avoidance of therapy-induced morbidity for low-risk patients, intensified treatment for high-risk patients comprises another challenge. With identification of specific risk features regarding molecular alterations, targeted therapy may represent an option for individualized treatment modalities in the future.

MYCN amplification in spinal ependymoma: A five-year retrospective study

Spinal ependymoma with MYCN amplification is a newly recognized type of spinal ependymoma that is known to be associated with poor prognosis. Available studies on this relatively rare tumor type have observed that these tumors tend to disseminate along the spinal cord and behave aggressively with worse overall and progression-free survival compared to the other types of ependymoma. In this study, we describe the clinical and histopathological features of spinal ependymomas in a single institution cohort with emphasis on those with MYCN amplification.

2021 World Health Organization Classification of Brain Tumors

OBJECTIVE

The classification of brain tumors is a rapidly evolving field that requires extensive integration of molecular diagnostic findings from an expanding set of platforms and assays. This article summarizes the schema presented in the 5th edition of the World Health Organization (WHO) classification of central nervous system (CNS) tumors while highlighting diagnostic molecular findings and discussing the strengths and weaknesses of commonly available testing modalities.

LATEST DEVELOPMENTS

Several major changes in practice were introduced with the 5th edition of the CNS WHO classification, including molecular grading of adult diffuse gliomas, the introduction of many new entities within the spectrum of pediatric gliomas and glioneuronal tumors, and the widespread adoption of methylation classes as useful or even necessary diagnostic criteria. Additionally, several revisions to nomenclature (eg, IDH-mutant gliomas) were introduced for simplicity and to disambiguate from other tumor types.

ESSENTIAL POINTS

The classification of brain tumors continues to grow in complexity alongside our improved understanding of their nuanced molecular underpinnings.

Spinal Ependymomas: An Updated WHO Classification and a Narrative Review

Ependymomas are neuroepithelial tumors that develop from ependymal cells found in the brain parenchyma and can spread to any part of the spinal cord. Three to six percent of all malignancies affecting the central nervous system (CNS) are ependymomas. Even the most talented surgeons are challenged by spinal cord ependymomas; as a result, research into this clinical phenomenon should continue. Since 1979, the World Health Organization (WHO) has published a classification and grading system for CNS malignancies to ensure consistent diagnostic standards worldwide. The WHO prepared an update on these tumors, paying particular attention to molecular techniques to categorize the therapeutic management of each patient with greater accuracy and clarity. We thoroughly reviewed the literature on the epidemiology, etiology, diagnosis, and treatment of spinal ependymomas since there has not been a recent review of these tumors. This included modifications to the 2021 WHO Classification of Tumors of the Central Nervous System.

Extensive Leptomeningeal Spreading of Ependymoma in an Adult: Case Report and Literature Review

Ependymoma is a rare adult tumor that originates from ependymal cells of the central nervous system, primarily occurring in the cerebral ventricles or the central canal of the spinal cord. In this paper, we report a case of extensive leptomeningeal seeding of ependymoma of a 39-year-old male patient, in whom the tumor was found incidentally after head trauma. The MRI exhibited diffuse leptomeningeal infiltrative lesions along with bilateral multiple cerebral sulci, basal cisterns, cerebellopontine angle, cerebellar folia. It also showed multinodular enhancing T1 low T2 high signal intensity lesions along the whole spinal cord. After the tumor biopsy at right temporal lesion, pathologic diagnosis was classic ependymoma (WHO grade 2). The patient has undergone radiation therapy and chemotherapy, and is currently maintaining a stable condition two years after surgery. This report suggests that when considering the differential diagnosis of extensive lesions both in the intracranial and intraspinal space, ependymoma should also be considered.

Conventional and Advanced Imaging of Spinal Cord Tumors

Spinal cord tumors are best identified by conventional MR imaging with contrast. Most intramedullary spinal cord tumors have characteristic MR imaging features that allow an accurate preoperative diagnosis. The spinal cord tumors reviewed in this article include the most common tumors, ependymomas and astrocytomas, as well as the less common tumors such as hemangioblastomas and metastases. Rare tumors such as primary CNS lymphoma and melanocytic tumors are also described. Advanced imaging techqniques of more common intramedullary tumors are also reviewed.

Latest classification of ependymoma in the molecular era and advances in its treatment: a review

Ependymoma is a rare central nervous system (CNS) tumour occurring in all age groups and is one of the most common paediatric malignant brain tumours. Unlike other malignant brain tumours, ependymomas have few identified point mutations and genetic and epigenetic features. With advances in molecular understanding, the latest 2021 World Health Organization (WHO) classification of CNS tumours divided ependymomas into 10 diagnostic categories based on the histology, molecular information and location; this accurately reflected the prognosis and biology of this tumour. Although maximal surgical resection followed by radiotherapy is considered the standard treatment method, and chemotherapy is considered ineffective, the validation of the role of these treatment modalities continues. Although the rarity and long-term clinical course of ependymoma make designing and conducting prospective clinical trials challenging, knowledge is steadily accumulating and progress is being made. Much of the clinical knowledge obtained from clinical trials to date was based on the previous histology-based WHO classifications, and the addition of new molecular information may lead to more complex treatment strategies. Therefore, this review presents the latest findings on the molecular classification of ependymomas and advances in its treatment.

A Radiologist's Guide to the 2021 WHO Central Nervous System Tumor Classification: Part 2-Newly Described and Revised Tumor Types

The fifth edition of the World Health Organization classification of tumors of the central nervous system (CNS), published in 2021, introduces major shifts in the classification of brain and spine tumors. These changes were necessitated by rapidly increasing knowledge of CNS tumor biology and therapies, much of which is based on molecular methods in tumor diagnosis. The growing complexity of CNS tumor genetics has required reorganization of tumor groups and acknowledgment of new tumor entities. For radiologists interpreting neuroimaging studies, proficiency with these updates is critical in providing excellent patient care. This review will focus on new or revised CNS tumor types and subtypes, beyond infiltrating glioma (described in part 1 of this series), with an emphasis on imaging features.

Classification and neuroimaging of ependymal tumors

Ependymal tumors arise from the ependymal cell remnants of the cerebral ventricles, the central canal of the spinal cord, or the filum terminale or conus medullaris, although most pediatric supratentorial ependymomas do not exhibit clear communication or abutment of the ventricles. In this article, we discuss the classification, imaging characteristics, and clinical settings of these tumors. The WHO 2021 classification system has categorized ependymal tumors based on histopathologic and molecular features and location, in which they are grouped as supratentorial, posterior fossa (PF), and spinal. The supratentorial tumors are defined by either the ZFTA (formerly RELA) fusion or the YAP1 fusion. Posterior fossa tumors are divided into group A and group B based on methylation. On imaging, supratentorial and infratentorial ependymomas may arise from the ventricles and commonly contain calcifications and cystic components, with variable hemorrhage and heterogeneous enhancement. Spinal ependymomas are defined by MYCN amplification. These tumors are less commonly calcified and may present with the "cap sign," with T2 hypointensity due to hemosiderin deposition. Myxopapillary ependymoma and subependymoma remain tumor subtypes, with no change related to molecular classification as this does not provide additional clinical utility. Myxopapillary ependymomas are intradural and extramedullary tumors at the filum terminale and/or conus medullaris and may also present the cap sign. Subependymomas are homogeneous when small and may be heterogeneous and contain calcifications when larger. These tumors typically do not demonstrate enhancement. Clinical presentation and prognosis vary depending on tumor location and type. Knowledge of the updated WHO classification of the central nervous system in conjunction with imaging features is critical for accurate diagnosis and treatment.

Clinical Characteristics, Management, and Outcomes of Intramedullary Spinal Cord Ependymomas in Adults: A Systematic Review

BACKGROUND

Intramedullary spinal cord ependymomas (IMSCEs) are rare tumors that mostly occur in adults. Management strategies and related outcomes are heterogeneously reported across the literature, demanding a comprehensive analysis to standardize guidelines. We performed a systematic review of the literature on IMSCEs.

METHODS

A literature search was conducted using 6 databases from inception up to July 28, 2022. Studies with data on clinical characteristics, management strategies, and related outcomes in adult patients with histopathologically confirmed IMSCEs were pooled and analyzed.

RESULTS

The analysis included 69 studies comprising 457 patients (52.7% males). Mean age was 42.4 ± 7.4 years. Sensory deficit (58.0%) was the most prevalent symptom, followed by radicular pain (50.5%). Tumors mostly involved the cervical (64.4%) or thoracic (18.8%) spinal cord and were mostly World Health Organization grade II (80.5%) and classic subtype (72.4%). Gross total resection was performed in most cases (83.4%), with adjuvant radiotherapy delivered in 10.5% of cases. Progression-free survival ≥2 years was reported in 61.1% of cases, and tumor recurrence or progression was reported in only 7.0% of the patients. At last follow-up, 97.4% of patients were alive.

CONCLUSIONS

IMSCEs are uncommon tumors that frequently manifest with debilitating symptoms that require surgical treatment. When feasible, gross total resection may be pursued to improve the patient's functional status and prevent tumor progression, with adjuvant radiotherapy required only in some more aggressive grade III lesions. Future studies should investigate different growth patterns and prognoses based on different IMSCE subtypes.

Epigenetic Regulation in Primary CNS Tumors: An Opportunity to Bridge Old and New WHO Classifications

Originally approved in 1979, a specific grading classification for central nervous system (CNS) tumors was devised by the World Health Organization (WHO) in an effort to guide cancer treatment and better understand prognosis. These "blue books" have since undergone several iterations based on tumor location, advancements in histopathology, and most recently, diagnostic molecular pathology in its fifth edition. As new research methods have evolved to elucidate complex molecular mechanisms of tumorigenesis, a need to update and integrate these findings into the WHO grading scheme has become apparent. Epigenetic tools represent an area of burgeoning interest that encompasses all non-Mendelian inherited genetic features affecting gene expression, including but not limited to chromatin remodeling complexes, DNA methylation, and histone regulating enzymes. The SWItch/Sucrose non-fermenting (SWI/SNF) chromatin remodeling complex is the largest mammalian family of chromatin remodeling proteins and is estimated to be altered in 20-25% of all human malignancies; however, the ways in which it contributes to tumorigenesis are not fully understood. We recently discovered that CNS tumors with SWI/SNF mutations have revealed an oncogenic role for endogenous retroviruses (ERVs), remnants of exogenous retroviruses that integrated into the germline and are inherited like Mendelian genes, several of which retain open reading frames for proteins whose expression putatively contributes to tumor formation. Herein, we analyzed the latest WHO classification scheme for all CNS tumors with documented SWI/SNF mutations and/or aberrant ERV expression, and we summarize this information to highlight potential research opportunities that could be integrated into the grading scheme to better delineate diagnostic criteria and therapeutic targets.

Newly Recognized CNS Tumors in the 2021 World Health Organization Classification: Imaging Overview with Histopathologic and Genetic Correlation

In 2021, the World Health Organization released an updated classification of CNS tumors. This update reflects the growing understanding of the importance of genetic alterations related to tumor pathogenesis, prognosis, and potential targeted treatments and introduces 22 newly recognized tumor types. Herein, we review these 22 newly recognized entities and emphasize their imaging appearance with correlation to histologic and genetic features.

In vivo loss of tumorigenicity in a patient-derived orthotopic xenograft mouse model of ependymoma

Introduction

Ependymomas (EPN) are the third most common malignant brain cancer in children. Treatment strategies for pediatric EPN have remained unchanged over recent decades, with 10-year survival rates stagnating at just 67% for children aged 0-14 years. Moreover, a proportion of patients who survive treatment often suffer long-term neurological side effects as a result of therapy. It is evident that there is a need for safer, more effective treatments for pediatric EPN patients. There are ten distinct subgroups of EPN, each with their own molecular and prognostic features. To identify and facilitate the testing of new treatments for EPN, in vivo laboratory models representative of the diverse molecular subtypes are required. Here, we describe the establishment of a patient-derived orthotopic xenograft (PDOX) model of posterior fossa A (PFA) EPN, derived from a metastatic cranial lesion.

Methods

Patient and PDOX tumors were analyzed using immunohistochemistry, DNA methylation profiling, whole genome sequencing (WGS) and RNA sequencing.

Results

Both patient and PDOX tumors classified as PFA EPN by methylation profiling, and shared similar histological features consistent with this molecular subgroup. RNA sequencing revealed that gene expression patterns were maintained across the primary and metastatic tumors, as well as the PDOX. Copy number profiling revealed gains of chromosomes 7, 8 and 19, and loss of chromosomes 2q and 6q in the PDOX and matched patient tumor. No clinically significant single nucleotide variants were identified, consistent with the low mutation rates observed in PFA EPN. Overexpression of EZHIP RNA and protein, a common feature of PFA EPN, was also observed. Despite the aggressive nature of the tumor in the patient, this PDOX was unable to be maintained past two passages in vivo.

Discussion

Others who have successfully developed PDOX models report some of the lowest success rates for EPN compared to other pediatric brain cancer types attempted, with loss of tumorigenicity not uncommon, highlighting the challenges of propagating these tumors in the laboratory. Here, we discuss our collective experiences with PFA EPN PDOX model generation and propose potential approaches to improve future success in establishing preclinical EPN models.

Changes to pediatric brain tumors in 2021 World Health Organization classification of tumors of the central nervous system

New tumor types are continuously being described with advances in molecular testing and genomic analysis resulting in better prognostics, new targeted therapy options and improved patient outcomes. As a result of these advances, pathological classification of tumors is periodically updated with new editions of the World Health Organization (WHO) Classification of Tumors books. In 2021, WHO Classification of Tumors of the Central Nervous System, 5^th edition (CNS5), was published with major changes in pediatric brain tumors officially recognized including pediatric gliomas being separated from adult gliomas, ependymomas being categorized based on anatomical compartment and many new tumor types, most of them seen in children. Additional general changes, such as tumor grading now being done within tumor types rather than across entities and changes in definition of glioblastoma, are also relevant to pediatric neuro-oncology practice. The purpose of this manuscript is to highlight the major changes in pediatric brain tumors in CNS5 most relevant to radiologists. Additionally, brief descriptions of newly recognized entities will be presented with a focus on imaging findings.

Major Features of the 2021 WHO Classification of CNS Tumors

Advances in the understanding of the molecular biology of central nervous system (CNS) tumors prompted a new World Health Organization (WHO) classification scheme in 2021, only 5 years after the prior iteration. The 2016 version was the first to include specific molecular alterations in the diagnoses of a few tumors, but the 2021 system greatly expanded this approach, with over 40 tumor types and subtypes now being defined by their key molecular features. Many tumors have also been reconceptualized into new "supercategories," including adult-type diffuse gliomas, pediatric-type diffuse low- and high-grade gliomas, and circumscribed astrocytic gliomas. Some entirely new tumors are in this scheme, particularly pediatric tumors. Naturally, these changes will impact how CNS tumor patients are diagnosed and treated, including clinical trial enrollment. This review addresses the most clinically relevant changes in the 2021 WHO book, including diffuse and circumscribed gliomas, ependymomas, embryonal tumors, and meningiomas.

Molecular testing for adolescent and young adult central nervous system tumors: A Canadian guideline

The 2021 World Health Organization (WHO) classification of CNS tumors incorporates molecular signatures with histology and has highlighted differences across pediatric vs adult-type CNS tumors. However, adolescent and young adults (AYA; aged 15–39), can suffer from tumors across this spectrum and is a recognized orphan population that requires multidisciplinary, specialized care, and often through a transition phase. To advocate for a uniform testing strategy in AYAs, pediatric and adult specialists from neuro-oncology, radiation oncology, neuropathology, and neurosurgery helped develop this review and testing framework through the Canadian AYA Neuro-Oncology Consortium. We propose a comprehensive approach to molecular testing in this unique population, based on the recent tumor classification and within the clinical framework of the provincial health care systems in Canada.

Major Changes in 2021 World Health Organization Classification of Central Nervous System Tumors

The World Health Organization (WHO) published the fifth edition of the WHO Classification of Tumors of the Central Nervous System (WHO CNS5) in 2021, as an update of the WHO central nervous system (CNS) classification system published in 2016. WHO CNS5 was drafted on the basis of recommendations from the Consortium to Inform Molecular and Practical Approaches to CNS Tumor Taxonomy (cIMPACT-NOW) and expounds the classification scheme of the previous edition, which emphasized the importance of genetic and molecular changes in the characteristics of CNS tumors. Multiple newly recognized tumor types, including those for which there is limited knowledge regarding neuroimaging features, are detailed in WHO CNS5. The authors describe the major changes introduced in WHO CNS5, including revisions to tumor nomenclature. For example, WHO grade IV tumors in the fourth edition are equivalent to CNS WHO grade 4 tumors in the fifth edition, and diffuse midline glioma, H3 K27M-mutant, is equivalent to midline glioma, H3 K27-altered. With regard to tumor typing, isocitrate dehydrogenase (IDH)-mutant glioblastoma has been modified to IDH-mutant astrocytoma. In tumor grading, IDH-mutant astrocytomas are now graded according to the presence or absence of homozygous CDKN2A/B deletion. Moreover, the molecular mechanisms of tumorigenesis, as well as the clinical characteristics and imaging features of the tumor types newly recognized in WHO CNS5, are summarized. Given that WHO CNS5 has become the foundation for daily practice, radiologists need to be familiar with this new edition of the WHO CNS tumor classification system. Online supplemental material and the slide presentation from the RSNA Annual Meeting are available for this article. ^©RSNA, 2022.

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.

Ependymoma: Evaluation and Management Updates

PURPOSE OF REVIEW

To review state of art and relevant advances in the molecular genetics and management of ependymomas of children and adults.

RECENT FINDINGS

Ependymomas may occur either in the brain or in the spinal cord. Compared with intracranial ependymomas, spinal ependymomas are less frequent and exhibit a better prognosis. The new WHO classification of CNS tumors of 2021 has subdivided ependymomas into different histomolecular subgroups with different outcome. The majority of studies have shown a major impact of extent of resection; thus, a complete resection must be performed, whenever possible, at first surgery or at reoperation. Conformal radiotherapy is recommended for grade 3 or incompletely resected grade II tumors. Proton therapy is increasingly employed especially in children to reduce the risk of neurocognitive and endocrine sequelae. Craniospinal irradiation is reserved for metastatic disease. Chemotherapy is not useful as primary treatment and is commonly employed as salvage treatment for patients failing surgery and radiotherapy. Standard treatments are still the mainstay of treatment: the discovery of new druggable pathways will hopefully increase the therapeutic armamentarium in the near future.

Essential Management of Pediatric Brain Tumors

Brain tumors are the most common solid tumors in children and are associated with high mortality. The most common childhood brain tumors are grouped as low-grade gliomas (LGG), high grade gliomas (HGG), ependymomas, and embryonal tumors, according to the World Health Organization (WHO). Advances in molecular genetics have led to a shift from pure histopathological diagnosis to integrated diagnosis. For the first time, these new criteria were included in the WHO classification published in 2016 and has been further updated in the 2021 edition. Integrated diagnosis is based on molecular genomic similarities of the tumor subclasses, and it can better explain the differences in clinical courses of previously histopathologically identical entities. Important advances have also been made in pediatric neuro-oncology. A growing understanding of the molecular-genetic background of tumorigenesis has improved the diagnostic accuracy. Re-stratification of treatment protocols and the development of targeted therapies will significantly affect overall survival and quality of life. For some pediatric tumors, these advances have significantly improved therapeutic management and prognosis in certain tumor subgroups. Some therapeutic approaches also have serious long-term consequences. Therefore, optimized treatments are greatly needed. Here, we discuss the importance of multidisciplinary collaboration and the role of (pediatric) neurosurgery by briefly describing the most common childhood brain tumors and their currently recognized molecular subgroups.

Intramedullary Spinal Cord Lesions: A Single-Center Experience

Objective: Spinal cord tumors constitute a small part of spinal surgery owing to their rarity. This retrospective study describes their current management.Methods: Forty-eight patients were treated for an intramedullary tumor between 2014 and 2020 at a single institution. Patients’ files were retrospectively studied. We detailed clinical status according to neurological deficit and ambulatory ability using the modified McCormick Scale, radiological features like number of levels, associated syringomyelia, surgical technique with or without intraoperative electrophysiological monitoring, pathological findings, and postoperative outcome.Results: The median age of this population was 43 years, including 5 patients under 18 years. The median delay before first neurosurgical contact was 3 months after the first clinical complaint. Treatment was gross total resection in 43.8%, subtotal resection in 50.0%, and biopsy in 6.2%. A laminectomy was performed for all the patients except 2 operated using the laminoplasty technique. Pathological findings were ependymoma in 43.8%, hemangioblastoma in 20.8%, and pilocytic astrocytoma in 10.4%. Six patients were reoperated for a tumor recurrence less than 2 years after the first surgical resection. One patient was reoperated for a postoperative cervical kyphosis.Conclusion: Intramedullary tumors are still a challenging disease and they are treated by various surgical techniques. They must be managed in a specialized center including a trained surgical, radiological, electrophysiological, and pathological team. Arthrodesis must be discussed before performing extensive laminectomy to avoid postoperative kyphosis.

Pediatric spinal intramedullary anaplastic myxopapillary ependymoma: a case report

A 6-year-old girl presented with a 1-week history of progressive upper and lower extremity weakness and bilateral upper extremity dysesthesia. Imaging demonstrated a 4.7 × 1.2-cm enhancing intramedullary lesion in the cervical spine from level C2 to C5 with associated cystic components and syringomyelia. The patient underwent a C2-C5 laminoplasty, with gross total resection of the intramedullary lesion. Histological analysis showed small to medium-sized epithelioid cells, with predominantly a solid architecture focally infiltrating into the adjacent spinal cord tissue. Focal papillary differentiation was present along with peri-vascular pseudorosettes, mucin microcysts, and globules of dense collagen. Focal anaplasia was noted with mitosis (5/10 HPF), focal necrosis, and elevated Ki67 10-15%. These findings were consistent with a myxopapillary ependymoma with anaplastic features. CSF cytology was negative for tumor cells. MYCN amplification was not present. She was treated with targeted proton-beam radiation therapy. This is the fourth case of an intramedullary anaplastic myxopapillary ependymoma to date, and the first case in the cervical spine reported in the literature.

EZHIP: a new piece of the puzzle towards understanding pediatric posterior fossa ependymoma

Ependymomas (EPN) are tumors of the central nervous system (CNS) that can arise in the supratentorial brain (ST-EPN), hindbrain or posterior fossa (PF-EPN) or anywhere in the spinal cord (SP-EPN), both in children and adults. Molecular profiling studies have identified distinct groups and subtypes in each of these anatomical compartments. In this review, we give an overview on recent findings and new insights what is driving PFA ependymomas, which is the most common group. PFA ependymomas are characterized by a young median age at diagnosis, an overall balanced genome and a bad clinical outcome (56% 10-year overall survival). Sequencing studies revealed no fusion genes or other highly recurrently mutated genes, suggesting that the disease is epigenetically driven. Indeed, recent findings have shown that the characteristic global loss of the repressive histone 3 lysine 27 trimethylation (H3K27me3) mark in PFA ependymoma is caused by aberrant expression of the enhancer of zeste homolog inhibitory protein (EZHIP) or in rare cases by H3K27M mutations, which both inhibit EZH2 thereby preventing the polycomb repressive complex 2 (PRC2) from spreading H3K27me3. We present the current status of the ongoing work on EZHIP and its essential role in the epigenetic disturbance of PFA biology. Comparisons to the oncohistone H3K27M and its role in diffuse midline glioma (DMG) are drawn, highlighting similarities but also differences between the tumor entities and underlying mechanisms. A strong focus is to point out missing information and to present directions of further research that may result in new and improved therapies for PFA ependymoma patients.

Diagnostic, therapeutic, and prognostic implications of the 2021 World Health Organization classification of tumors of the central nervous system

The 2016 revised fourth edition of the World Health Organization (WHO) classification of central nervous system (CNS) tumors incorporated molecular features with histologic grading, revolutionizing how oncologists conceptualize primary brain and spinal cord tumors as well as providing new insights into their management and prognosis. The 2021 revised fifth edition of the WHO classification further integrates molecular alterations for CNS tumor categorization, updating current understanding of the pathophysiology of many of these disease entities. Here, the authors review changes in the new classification for the most common primary adult tumors-gliomas (including astrocytomas, oligodendrogliomas, and ependymomas) and meningiomas-highlighting the key genomic alterations for each group classification to help clinicians interpret them as they consider therapeutic options-including clinical trials and targeted therapies-and discuss the prognosis of these tumors with their patients. The revised, updated 2021 WHO classification also further integrates molecular alterations in the classification of pediatric CNS tumors, but those are not covered in the current review.

Ependymal Tumors

Ependymomas (EPN) are commonly encountered brain tumors in the pediatric population. They may arise in the supratentorial compartment, posterior fossa and spinal cord. Histopathologic grading of EPN has always been challenging with poor interobserver reproducibility and lack of correlation between histologic grade and patient outcomes. Recent studies have highlighted that, despite histopathological similarities among variants of EPN at different anatomical sites, they possess site-specific genetic and epigenetic alterations, transcriptional profiles and DNA copy number variations. This has led to a molecular and location-based classification for EPN which has been adopted by the World Health Organization Classification of Central Nervous System Tumors and more accurately risk-stratifies patients than histopathologic grading alone. Given the complexity of this evolving field, the purpose of this paper is to offer a practical approach to the diagnosis of EPN, including the selection of the most appropriate molecular surrogate immunohistochemical stains, basic molecular studies and more sophisticated techniques if needed. The goal is to reach a rapid, sound diagnosis, providing essential information regarding prognosis and guiding clinical decision-making.

Clinically aggressive pediatric spinal ependymoma with novel MYC amplification demonstrates molecular and histopathologic similarity to newly described MYCN-amplified spinal ependymomas

Primary spinal cord tumors contribute to ≤ 10% of central nervous system tumors in individuals of pediatric or adolescent age. Among intramedullary tumors, spinal ependymomas make up ~ 30% of this rare tumor population. A twelve-year-old male presented with an intradural, extramedullary mass occupying the dorsal spinal canal from C6 through T2. Gross total resection and histopathology revealed a World Health Organization (WHO) grade 2 ependymoma. He recurred eleven months later with extension from C2 through T1-T2. Subtotal resection was achieved followed by focal proton beam irradiation and chemotherapy. Histopathology was consistent with WHO grade 3 ependymoma. Molecular profiling of the primary and recurrent tumors revealed a novel amplification of the MYC (8q24) gene, which was confirmed by fluorescence in situ hybridization studies. Although MYC amplification in spinal ependymoma is exceedingly rare, a newly described classification of spinal ependymoma harboring MYCN (2p24) amplification (SP-MYCN) has been defined by DNA methylation-array based profiling. These individuals typically present with a malignant progression and dismal outcomes, contrary to the universally excellent survival outcomes seen in other spinal ependymomas. DNA methylation array-based classification confidently classified this tumor as SP-MYCN ependymoma. Notably, among the cohort of 52 tumors comprising the SP-MYCN methylation class, none harbor MYC amplification, highlighting the rarity of this genomic amplification in spinal ependymoma. A literature review comparing our individual to reported SP-MYCN tumors (n = 26) revealed similarities in clinical, histopathologic, and molecular features. Thus, we provide evidence from a single case to support the inclusion of MYC amplified spinal ependymoma within the molecular subgroup of SP-MYCN.

Molecular Classification and Therapeutic Targets in Ependymoma

Ependymoma is a biologically diverse tumor wherein molecular classification has superseded traditional histological grading based on its superior ability to characterize behavior, prognosis, and possible targeted therapies. The current, updated molecular classification of ependymoma consists of ten distinct subgroups spread evenly among the spinal, infratentorial, and supratentorial compartments, each with its own distinct clinical and molecular characteristics. In this review, the history, histopathology, standard of care, prognosis, oncogenic drivers, and hypothesized molecular targets for all subgroups of ependymoma are explored. This review emphasizes that despite the varied behavior of the ependymoma subgroups, it remains clear that research must be performed to further elucidate molecular targets for these tumors. Although not all ependymoma subgroups are oncologically aggressive, development of targeted therapies is essential, particularly for cases where surgical resection is not an option without causing significant morbidity. The development of molecular therapies must rely on building upon our current understanding of ependymoma oncogenesis, as well as cultivating transfer of knowledge based on malignancies with similar genomic alterations.

Rare sacral extradural grade II ependymoma: a comprehensive review of literature

Sacral spinal cord ependymoma is an uncommon pathology. Most of the reported cases are consistent with a myxopapillary ependymoma histopathologic subtype. Non-myxopapillary ependymomas rarely occur in the sacral region. Most lesions are intradural; however, rare extradural cases can occur. We present the case of a 46-year-old female patient diagnosed with a grade II sacral extradural ependymoma, emphasising the importance of an interdepartmental case approach for diagnosis and management. Even though grade II ependymomas are considered low grade, the potential for recurrence and metastatic disease has been reported. There are no treatment guidelines for these rare tumours besides gross total resection.

Pediatric Myxopapillary Ependymomas: A Clinicopathologic Evaluation

Myxopapillary ependymomas (MPEs) have an indolent clinical course, corresponding to World Health Organization Grade I. A total of 13 pediatric MPEs have been reported in the literature with "anaplastic features," including elevated proliferative activity (≥5 mitoses/10 high-power fields), necrosis, and microvascular proliferation. No consensus exists regarding the prognostic significance of such features. A retrospective clinicopathologic review of pediatric MPEs diagnosed between 1996 and 2018 at Mayo Clinic was performed. Totally, 8 pediatric MPEs (6 male; age: 7.52 to 16.88 y) were identified. Totally, 3 had disseminated disease at presentation. All patients underwent surgical resection (7 gross total; 1 subtotal). Totally, 5 cases harbored ≥5 mitoses/10 high-power fields (range: 5 to 9), 3 of which showed necrosis (2 with disseminated disease). Postsurgery, 2 patients received radiation; one with disseminated disease and another with increased mitotic activity/necrosis; neither has recurred (follow-up: 1.18 and 3.19 y). In all, 2 patients with disseminated disease, elevated mitotic activity, and necrosis had new metastatic disease/progression of nonresected metastatic foci (2.6 and 26.8 mo), received radiation therapy, and remain progression free (3.01 and 9.34 y). All patients are alive (median follow-up 1.31 y, range: 0.66 to 11.75). Among pediatric MPEs, the concurrent presence of elevated mitotic activity and necrosis may be associated with an aggressive clinical course, warranting closer surveillance and consideration of adjuvant therapies.

Molecular Stratification of Childhood Ependymomas as a Basis for Personalized Diagnostics and Treatment

Ependymomas are among the most enigmatic tumors of the central nervous system, posing enormous challenges for pathologists and clinicians. Despite the efforts made, the treatment options are still limited to surgical resection and radiation therapy, while none of conventional chemotherapies is beneficial. While being histologically similar, ependymomas show considerable clinical and molecular diversity. Their histopathological evaluation alone is not sufficient for reliable diagnostics, prognosis, and choice of treatment strategy. The importance of integrated diagnosis for ependymomas is underscored in the recommendations of Consortium to Inform Molecular and Practical Approaches to CNS Tumor Taxonomy. These updated recommendations were adopted and implemented by WHO experts. This minireview highlights recent advances in comprehensive molecular-genetic characterization of ependymomas. Strong emphasis is made on the use of molecular approaches for verification and specification of histological diagnoses, as well as identification of prognostic markers for ependymomas in children.

Impact of the methylation classifier and ancillary methods on CNS tumor diagnostics

BACKGROUND

Accurate CNS tumor diagnosis can be challenging, and methylation profiling can serve as an adjunct to classify diagnostically difficult cases.

METHODS

An integrated diagnostic approach was employed for a consecutive series of 1,258 surgical neuropathology samples obtained primarily in a consultation practice over 2-year period. DNA methylation profiling and classification using the DKFZ/Heidelberg CNS tumor classifier was performed, as well as unsupervised analyses of methylation data. Ancillary testing, where relevant, was performed.

RESULTS

Among the received cases in consultation, a high confidence methylation classifier score (>0.84) was reached in 66.4% of cases. The classifier impacted the diagnosis in 46.5% of these high-confidence classifier score cases, including a substantially new diagnosis in 26.9% cases. Among the 289 cases received with only a descriptive diagnosis, methylation was able to resolve approximately half (144, 49.8%) with high-confidence scores. Additional methods were able to resolve diagnostic uncertainty in 41.6% of the low-score cases. Tumor purity was significantly associated with classifier score (p = 1.15e-11). Deconvolution demonstrated that suspected GBMs matching as control/inflammatory brain tissue could be resolved into GBM methylation profiles, which provided a proof-of-concept approach to resolve tumor classification in the setting of low tumor purity.

CONCLUSIONS

This work assesses the impact of a methylation classifier and additional methods in a consultative practice by defining the proportions with concordant vs. change in diagnosis in a set of diagnostically challenging CNS tumors. We address approaches to low-confidence scores and confounding issues of low tumor purity.

Intradural Pediatric Spinal Tumors: An Overview from Imaging to Novel Molecular Findings

Pediatric spinal tumors are rare and account for 10% of all central nervous system tumors in children. Onset usually occurs with chronic nonspecific symptoms and may depend on the intra- or extradural neoplastic location. Meningiomas, schwannomas, and neurofibromas are the most common intradural-extramedullary lesions, while astrocytomas and ependymomas represent the majority of intramedullary tumors. The new molecular discoveries regarding pediatric spinal cancer currently contribute to the diagnostic and therapeutic processes. Moreover, some familial genetic syndromes can be associated with the development of spinal tumors. Currently, magnetic resonance imaging (MRI) is the standard reference for the evaluation of pediatric spinal tumors. Our aim in this review was to describe the imaging of the most frequent intradural intra/extramedullary pediatric spinal tumors and to investigate the latest molecular findings and genetic syndromes.

Local and systemic therapy of recurrent ependymoma in children and adolescents: short- and long-term results of the E-HIT-REZ 2005 study

BACKGROUND

Survival in recurrent ependymomas in children and adolescents mainly depends on the extent of resection. Studies on repeated radiotherapy and chemotherapy at relapse have shown conflicting results.

METHODS

Using data from the German multi-center E-HIT-REZ-2005 study, we examined the role of local therapy and the efficacy of chemotherapy with blockwise temozolomide (TMZ) in children and adolescents with recurrent ependymomas.

RESULTS

Fifty-three patients with a median age of 6.9 years (1.25-25.4) at first recurrence and a median follow-up time of 36 months (2-115) were recruited. Gross- and near-total resection (GTR/NTR) were achieved in 34 (64.2%) patients and associated with a markedly improved 5-year overall survival (OS) of 48.7% vs. 5.3% in less than GTR/NTR. Radiotherapy showed no improvement in OS following complete resection (OS: 70 (CI: 19.9-120.1) vs. 95 (CI: 20.7-169.4) months), but an advantage was found in less than GTR/NTR (OS: 22 (CI: 12.7-31.3) vs. 7 (CI: 0-15.8) months). Following the application of TMZ, disease progression was observed in most evaluable cases (18/21). A subsequent change to oral etoposide and trofosfamide showed no improved response. PF-A EPN were most abundant in relapses (n = 27). RELA-positive EPN (n = 5) had a 5-year OS of 0%.

CONCLUSION

The extent of resection is the most important predictor of survival at relapse. Focal re-irradiation is a useful approach if complete resection cannot be achieved, but no additional benefit was seen after GTR/NTR. Longer-term disease stabilization (>6 months) mediated by TMZ occurred in a small number of cases (14.3%).

[Histomolecular diagnosis of glial and glioneuronal tumours]

While rare compared to extra-cranial neoplasms, glial and glioneuronal tumors are responsible of high morbidity and mortality. In 2016, the World Health Organization introduced histo-molecular ("integrated") diagnostics for central nervous system tumors based on morphology, immunohistochemistry and the presence of key genetic alterations. This combined phenotypic-genotypic classification allows for a more objective diagnostic of brain tumors. The implementation of such a classification in daily practice requires immunohistochemical surrogates to detect common genetic alterations and sometimes expensive and not widely available molecular biology techniques. The first step in brain tumor diagnostics is to inquire about the clinical picture and the imaging findings. When dealing with a glial tumor, the pathologist needs to assess its nature, infiltrative or circumscribed. If the tumor is infiltrative, IDH1/2 genes (prognostic marker) and chromosomes 1p/19q (diagnosis of oligodendroglioma) need to be assessed. If the tumor appears circumscribed, the pathologist should look for a neuronal component associated with the glial component (glioneuronal tumor). A limited immunohistochemistry panel will help distinguish between diffuse glioma (IDH1-R132H, ATRX, p53) and circumscribed glial/glioneuronal tumor (CD34, neuronal markers, BRAF-V600E), and some antibodies may reliably detect genetic alterations (IDH1-R132H, BRAF-V600E and H3-K27M mutations). Chromosomal imbalances (1p/19q codeletion in oligodendroglioma; chromosome 7 gain/chromosome 10 loss and EGFR amplification in glioblastoma) and gene rearrangements (BRAF fusion, FGFR1 fusion) will be identified by molecular biology techniques. The up-coming edition of the WHO classification of the central nervous system tumors will rely more heavily on molecular alterations to accurately diagnose and treat brain tumors.

Integrative molecular characterization of pediatric spinal ependymoma: the UK Children's Cancer and Leukaemia Group study

Background

Pediatric spinal ependymomas (SP-EPNs) are rare primary central nervous system tumors with heterogeneous clinical course. Considering that ependymomas in children are biologically distinct from their adult counterparts, this study aimed to define the molecular landscape of SP-EPNs in children.

Methods

In this retrospective study, we have collected tumor samples from 27 SP-EPN patients younger than 18 years and carried out the histological review, DNA methylation, and gene expression profiling.

Results

Unsupervised analyses with methylation profiles revealed 2 subgroups where all grade I tumors (n = 11) were in Group 1, but the grade II/III tumors split into 2 groups (n = 7 in Group 1 and n = 9 in Group 2). The Heidelberg classifier assigned Group 1 tumors as spinal myxopapillary ependymomas (SP-MPEs), 5 Group 2 tumors as SP-EPNs, and failed to classify 4 Group 2 tumors. Copy numbers derived from DNA methylation arrays revealed subgroup-specific genetic alterations and showed that SP-EPN tumors lack MYCN amplification. Gene expression profiling revealed distinct transcriptomic signatures, including overexpression of genes involved in oxidative phosphorylation in SP-MPEs that were validated by Western blot analysis. We discovered widespread decreases in DNA methylation at enhancer regions that are associated with the expression of oncogenic signaling pathways in SP-MPEs. Furthermore, transcription factor motifs for master regulators, including HNF1B, PAX3, and ZIC3, were significantly overrepresented in probes specific to distal regulatory regions in SP-MPEs.

Conclusion

Our findings show substantial heterogeneity in pediatric SP-EPN and uncover novel enhancers and transcriptional pathways specific to the SP-MPE subgroup, providing a foundation for future therapeutic strategies.

mRNA and miRNA Expression Analyses of the MYC/E2F/miR-17-92 Network in the Most Common Pediatric Brain Tumors

Numerous molecular factors disrupt the correctness of the cell cycle process leading to the development of cancer due to increased cell proliferation. Among known causative factors of such process is abnormal gene expression. Nowadays in the light of current knowledge such alterations are frequently considered in the context of mRNA–miRNA correlation. One of the molecular factors with potential value in tumorigenesis is the feedback loop between MYC and E2F genes in which miR-17-5p and miR-20a from the miR-17-92 cluster are involved. The current literature shows that overexpression of the members of the OncomiR-1 are involved in the development of many solid tumors. In the present work, we investigated the expression of components of the MYC/E2F/miR-17-92 network and their closely related elements including members of MYC and E2F families and miRNAs from two paralogs of miR-17-92: miR-106b-25 and miR-106a-363, in the most common brain tumors of childhood, pilocytic astrocytoma (PA), WHO grade 1; ependymoma (EP), WHO grade 2; and medulloblastoma (MB), WHO grade 4. We showed that the highest gene expression was observed in the MYC family for MYCN and in the E2F family for E2F2. Positive correlation was observed between the gene expression and tumor grade and type, with the highest expression being noted for medulloblastomas, followed by ependymomas, and the lowest for pilocytic astrocytomas. Most members of miR-17-92, miR-106a-363 and miR-106b-25 clusters were upregulated and the highest expression was noted for miR-18a and miR-18b. The rest of the miRNAs, including miR-19a, miR-92a, miR-106a, miR-93, or miR-25 also showed high values. miR-17-5p, miR-20a obtained a high level of expression in medulloblastomas and ependymomas, while close to the control in the pilocytic astrocytoma samples. miRNA expression also depended on tumor grade and histology.

Pediatric ependymoma: an overview of a complex disease

Pediatric ependymomas comprise biologically distinct tumor entities with different (epi)genetics, age distribution and localization, as well as a different prognosis. Regarding risk stratification within these biologically defined entities, histopathological features still seem to be relevant. The mainstay of treatment is gross total resection (GTR) if possible, achieved with intraoperative monitoring and neuronavigation-and if necessary second surgery-followed by adjuvant radiation therapy. However, there is growing evidence that some ependymal tumors may be cured by surgery alone, while others relapse despite adjuvant treatment. To date, the role of chemotherapy is not clear. Current therapy achieves reasonable survival rates for the majority of ependymoma patients. The next challenge is to go beyond initial tumor control and use risk-adapted therapy to reduce secondary effect and therapy-induced morbidity for low-risk patients and to intensify treatment for high-risk patients. With identification of specific alterations, targeted therapy may represent an option for individualized treatment modalities in the future.

Case Report: Sellar Ependymomas: A Clinic-Pathological Study and Literature Review

Ependymomas are primary glial tumors arising from cells related to the ependymal lining of the ventricular system. They are classified into at least nine different molecular subtypes according to molecular phenotype, histological morphology, and tumor location. Primary sellar ependymoma is an extremely rare malignancy of the central nervous system, with only 12 known cases reported in humans. We herein report a case of ependymoma located at the pituitary region in a 44-year-old female patient and discuss the molecular subtype, natural history, clinical presentation, radiological findings, histological features, immunohistochemical characteristics, ultrastructural examinations, treatment, and prognosis of sellar ependymoma. This case report may serve as a helpful reference for clinicians and radiologists in clinical practice.

cIMPACT-NOW update 7: advancing the molecular classification of ependymal tumors

Advances in our understanding of the biological basis and molecular characteristics of ependymal tumors since the latest iteration of the World Health Organization (WHO) classification of CNS tumors (2016) have prompted the cIMPACT-NOW group to recommend a new classification. Separation of ependymal tumors by anatomic site is an important principle of the new classification and was prompted by methylome profiling data to indicate that molecular groups of ependymal tumors in the posterior fossa and supratentorial and spinal compartments are distinct. Common recurrent genetic or epigenetic alterations found in tumors belonging to the main molecular groups have been used to define tumor types at intracranial sites; C11orf95 and YAP1 fusion genes for supratentorial tumors and two types of posterior fossa ependymoma defined by methylation group, PFA and PFB. A recently described type of aggressive spinal ependymoma with MYCN amplification has also been included. Myxopapillary ependymoma and subependymoma have been retained as histopathologically defined tumor types, but the classification has dropped the distinction between classic and anaplastic ependymoma. While the cIMPACT-NOW group considered that data to inform assignment of grade to molecularly defined ependymomas are insufficiently mature, it recommends assigning WHO grade 2 to myxopapillary ependymoma and allows grade 2 or grade 3 to be assigned to ependymomas not defined by molecular status.

High level MYCN amplification and distinct methylation signature define an aggressive subtype of spinal cord ependymoma

We report a novel group of clinically aggressive spinal cord ependymomas characterized by Grade III histology, MYCN amplification, an absence of NF2 alterations or other recurrent pathogenic mutations, and a unique methylation classifier profile. Seven cases were found to have MYCN amplification in the course of routine mutational profiling of 552 patients with central nervous system tumors between December 2016 and July of 2019 and an eighth patient was identified from an unrelated set of cases. Methylation array analysis revealed that none of the 8 cases clustered with any of the nine previously described ependymoma methylation subgroups, and 7 of 8 formed their own tight unique cluster. Histologically all cases showed grade III features, and all demonstrated aggressive clinical behavior. These findings are presented in the context of data from three other studies describing similar cases. Therefore, a combined total of 27 MYCN amplified spinal cord ependymoma cases have now been reported in the literature, warranting their consideration as a distinctive subtype of spinal cord ependymoma (SP-EPN-MYCN) with their unique molecular characteristics and aggressive clinical behavior.

cIMPACT-NOW update 6: new entity and diagnostic principle recommendations of the cIMPACT-Utrecht meeting on future CNS tumor classification and grading

cIMPACT-NOW (the Consortium to Inform Molecular and Practical Approaches to CNS Tumor Taxonomy) was established to evaluate and make practical recommendations on recent advances in the field of CNS tumor classification, particularly in light of the rapid progress in molecular insights into these neoplasms. For Round 2 of its deliberations, cIMPACT-NOW Working Committee 3 was reconstituted and convened in Utrecht, The Netherlands, for a meeting designed to review putative new CNS tumor types in advance of any future World Health Organization meeting on CNS tumor classification. In preparatory activities for the meeting and at the actual meeting, a list of possible entities was assembled and each type and subtype debated. Working Committee 3 recommended that a substantial number of newly recognized types and subtypes should be considered for inclusion in future CNS tumor classifications. In addition, the group endorsed a number of principles-relating to classification categories, approaches to classification, nomenclature, and grading-that the group hopes will also inform the future classification of CNS neoplasms.

Invited Review: DNA methylation-based classification of paediatric brain tumours

DNA methylation-based machine learning algorithms represent powerful diagnostic tools that are currently emerging for several fields of tumour classification. For various reasons, paediatric brain tumours have been the main driving forces behind this rapid development and brain tumour classification tools are likely further advanced than in any other field of cancer diagnostics. In this review, we will discuss the main characteristics that were important for this rapid advance, namely the high clinical need for improvement of paediatric brain tumour diagnostics, the robustness of methylated DNA and the consequential possibility to generate high-quality molecular data from archival formalin-fixed paraffin-embedded pathology specimens, the implementation of a single array platform by most laboratories allowing data exchange and data pooling to an unprecedented extent, as well as the high suitability of the data format for machine learning. We will further discuss the four most central output qualities of DNA methylation profiling in a diagnostic setting (tumour classification, tumour sub-classification, copy number analysis and guidance for additional molecular testing) individually for the most frequent types of paediatric brain tumours. Lastly, we will discuss DNA methylation profiling as a tool for the detection of new paediatric brain tumour classes and will give an overview of the rapidly growing family of new tumours identified with the aid of this technique.