Analysis of chromosome 19q13.42 amplification in embryonal brain tumors with ependymoblastic multilayered rosettes

Embryonal Tumors of the Central Nervous System with Multilayered Rosettes and Atypical Teratoid/Rhabdoid Tumors

The 2016 WHO classification of tumors of the central nervous system affected importantly the group of CNS embryonal tumors. Molecular analysis on methylome, genome, and transcriptome levels allowed better classification, identification of specific molecular hallmarks of the different subtypes of CNS embryonal tumors, and their more precise diagnosis. Routine application of appropriate molecular testing and standardized reporting are of pivotal importance for adequate prognosis and treatment, but also for epidemiology studies and search for efficient targeted therapies. As a result of this approach, the term primitive neuroectodermal tumor-PNET was removed and a new clinic-pathological entity was introduced-Embryonal tumor with multilayered rosettes (ETMR). The group of CNS embryonal tumors include also medulloblastoma, medulloepithelioma, CNS neuroblastoma, CNS ganglioneuroblastoma, atypical teratoid/rhabdoid tumor (ATRT) and their subtypes. This chapter will focus mainly on ETMR and ATRT. Embryonal tumors with multilayered rosettes and the atypical teratoid/rhabdoid tumors are undifferentiated or poorly differentiated tumors of the nervous system that originate from primitive brain cells, develop exclusively in childhood or adolescence, and are characterized by a high degree of malignancy, aggressive evolution and a tendency to metastasize to the cerebrospinal fluid. Their clinical presentation is similar to other malignant, intracranial, neoplastic lesions and depends mainly on the localization of the tumor, the rise of the intracranial pressure, and eventually the obstruction of the cerebrospinal fluid pathways. The MRI image characteristics of these tumors are largely overlappingintra-axial, hypercellular, heterogeneous tumors, frequently with intratumoral necrosis and/or hemorrhages. Treatment options for ETMR and ATRT are very restricted. Surgery can seldom achieve radical excision. The rarity of the disease hampers the establishment of a chemotherapy protocol and the usual age of the patients limits severely the application of radiotherapy as a therapeutic option. Consequently, the prognosis of these undifferentiated, malignant, aggressive tumors remains dismal with a 5-year survival between 0 and 30%.

Prognostic impact of the multimodal treatment approach in patients with C19MC-altered embryonal tumor with multilayered rosettes

OBJECTIVE

Embryonal tumor with multilayered rosettes (ETMR) is one of the childhood central nervous system tumors with the poorest prognosis; thus, establishing an optimal treatment strategy is essential, However, because of the low incidence and molecular heterogeneity of the tumor, the optimal treatment has not yet been determined. In this study the authors evaluated the prognostic impact of a multimodal treatment approach in patients with ETMR.

METHODS

The authors evaluated 4 patients with ETMR at their institution who showed varied clinical features and also conducted clinical characterization and prognostic analysis of previously reported cases of the ETMR-presenting locus 19q13.42 with a chromosome 19 microRNA cluster (C19MC) amplification, which is known to be a diagnostic hallmark of the tumor.

RESULTS

Of the 4 patients with ETMR in the authors' institution, in 1 case the patient's tumor showed a neuroblastoma-like appearance without multilayered rosettes; however, the diagnosis was confirmed by the presence of amplified C19MC. From a clinical standpoint, 2 patients who underwent gross-total resection (GTR) of the tumor and chemotherapy followed by high-dose chemotherapy (HDC) had long-term complete remission with or without local irradiation. In the multivariate analysis of 43 cases with C19MC-altered ETMR reported in the literature, HDC and local irradiation were significantly correlated with better event-free survival (HR 0.17, p = 0.0087; HR 0.17, p = 0.010) and overall survival (OS) (HR 0.29, p = 0.023; HR 0.28, p = 0.019), respectively. GTR was also correlated with better OS (HR 0.40, p = 0.039).

CONCLUSIONS

This case series demonstrated pathological and clinical heterogeneity among ETMR cases and the diagnostic importance of the molecular genetic approach among embryonal tumors, particularly during infancy. Based on the results of the analysis of molecularly uniformed ETMR cases, multimodal treatment may play a significant role in the prognosis of these tumors.

A surgical case of pediatric spinal medulloepithelioma

Embryonal tumor with multilayered rosettes (ETMR), C19MC-altered was introduced to the World Health Organization classification of central nervous system tumors in 2016. It is characterized by amplification or fusion of the chromosome 19 microRNA cluster (C19MC) locus at 19q13.42. Medulloepithelioma also an ETMR but lacks C19MC alteration. We report a rare case of spinal medulloepithelioma in a 2-year-old boy and review the literature.

[Embryonal tumor with multilayered rosettes (ETMR): case report and literature review]

Embryonal tumor with multilayered rosettes (ETMR) is a rare and highly malignant brain tumor that develops in children younger 4 years old. This neoplasm is characterized by extremely aggressive course, low sensitivity to chemotherapy and radiotherapy. Thanks to the progress of pathologists, diagnosis of ETMR is now available using immunohistochemical examination with LIN28A and SALL4 antibodies. Moreover, detection of microRNA amplification in the 19q13.42 locus by fluorescent hybridization in situ allows an unmistakable diagnosis. The authors describe clinical course and treatment outcome in a 2-year-old patient with a giant tumor of the right parietotemporal region. Postoperative histological examination verified ETMR. Despite adjuvant treatment, we observed fast progression of disease and unfavorable outcome after 5 months. Case report is supplemented by literature review.

CONCLUSION

ETMR is very rare and poorly understood neoplasm. The authors present a giant hemispheric ETMR in a 2-year-old boy with an extremely aggressive course of disease. Despite the advances in diagnosis and treatment of CNS tumors in children, there are currently more questions than answers regarding ETMR. Pooled analysis of all available data with large-scale studies is needed. It is necessary to emphasize an exceptional role of each clinical case for global study of this tumor. Timely adjuvant/neoadjuvant therapy in highly specialized centers is also essential.

Embryonal tumor with multilayered rosettes; rare pediatric CNS tumor. A case report and review of literature

Embryonal tumor with multilayered rosettes (ETMR), C19MC-altered is a newly designated entity of the embryonal tumors of the central nervous system (CNS) according to the 2016 WHO classification system of CNS. Characteristically, these tumors are newly defined based on their specific molecular genetic amplification in chromosome 19q13.42 found at locus C19MC. To the best of our knowledge, we present the first reported case of ETMR in Saudi Arabian pediatric population. A 2-year-old boy presented to the hospital with generalized tonic-colonic seizure, vomiting, irritability, and inability to walk. Computed tomography (CT) scan showed a large left thalamic supratentorial brain tumor. The tumor measured 6.1 × 5.6 × 5.6 cm and was characterized by cystic changes, prominent vasculature, and calcifications. Histopathology, immunohistochemistry examination, and fluorescence in situ hybridization (FISH) analysis confirmed the diagnosis of ETMR. In addition to reporting this rare case, we provide a brief literature review, treatment options, patient outcome, and disease prognosis.

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Embryonal tumor with multilayered rosettes (ETMR), C19MC-altered is a new entity of the embryonal brain tumors.

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Genomic alterations include a gain of chromosome 2, gain of chromosome 11, and gain/low-level amplification of 19q13.42 (ultimately resulting in TTYH1-C19MC fusion).

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The clinical behavior is usually aggressive, with dismal with poor outcome.

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Histopathologic evaluation, immunohistochemistry, and fluorescence in situ hybridization (FISH) analysis are required to confirm the diagnosis of ETMR.

C19MC amplification and expression of Lin28A and Olig2 in the classification of embryonal tumors of the central nervous system: A 14-year retrospective study from a tertiary care center

INTRODUCTION

CNS embryonal tumors (CET) other than medulloblastomas (MB) and atypical teratoid/rhabdoid tumors (AT/RTs), previously designated as 'central nervous system primitive neuroectodermal tumors' ('CNS PNETs'), are a heterogenous subset of tumors with poorly defined diagnostic criteria. Other than the subset of embryonal tumor with multilayered rosettes (ETMR) defined by C19MC amplification, most CETs are diagnosed by exclusion of other molecularly defined entities and histological mimics including MB, AT/RTs, and high-grade gliomas, and termed as CET, not otherwise specified (NOS) in the 2016 WHO classification.

AIM

To reclassify 'CNS PNETs' as per WHO 2016, and estimate the true proportion of CET, NOS in a tertiary healthcare setting, and to evaluate the diagnostic utility of C19MC amplification, Lin28A and Olig2 expression in the subclassification of CETs.

METHODS

Previously diagnosed cases of 'CNS PNETs' (2002-2016) were first evaluated by immunohistochemistry (IHC) for MIC2, RelaA, L1CAM, IDH1R132H, H3K27M, H3G34R, H3G34V, INI1, and BRG1 proteins and by fluorescence in-situ hybridization (FISH) for EWSR1 translocation to exclude histological mimics. The selected CETs (case cohort) and 79 histological mimics (comparison cohort) comprising of MB, AT/RT, pineal parenchymal tumors, Ewing sarcoma, esthesioneuroblastoma, intraocular medulloepithelioma, and H3G34R mutant high-grade glioma were subject to IHC for Olig2 and Lin28A, and FISH for C19MC amplification.

RESULTS

Twenty-two cases of 'CNS PNETs' were retrieved, all of which were negative for the first panel of markers and showed retained INI-1/BRG1 expression. Three of them (3/22, 13.6%) showed C19MC amplification (ETMR, C19MC-altered) with ETMR histology, Lin28A positivity, and Olig2 negativity. Among the remaining 19 CETs, one showed medulloepithelioma histology (Medulloepithelioma, NOS) and remaining were non-descript small round cell tumors (CET, NOS), all negative for Lin28A. Olig2 was positive in only 3 CETs (13.6%), all being CET, NOS. All tumors in the comparison cohort were negative for C19MC amplification, Lin28A and Olig2 except for 27% of ATRTs that were Lin28A positive.

CONCLUSION

ETMR, C19MC-altered constitute less than 14% of CETs, with majority remaining uncharacterized as CET, NOS. Lin28A is 100% sensitive for the detection of C19MC amplification; however, its specificity is limited by its expression in ATRTs. Olig2 expression is seen only in a small subset of CET, NOS and is of limited diagnostic utility.

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.

Embryonal tumors with multi-layered rosettes: a disease of dysregulated miRNAs

INTRODUCTION

ETMRs are highly lethal, pediatric embryonal brain tumors, previously classified as various histologic diagnoses including supratentorial primitive neuroectodermal tumors (sPNET) and CNS PNET. With recognition that these tumors harbor recurrent amplification of a novel oncogenic miRNA cluster on chr19, C19MC, ETMRs were designated as a distinct biological and molecular entity with a spectrum of histologic and clinical manifestations.

METHODS

We reviewed published literature describing clinical presentation, the genetic and epigenetic drivers of oncogenesis, and recent therapeutic strategies adopted to combat these aggressive tumors.

RESULTS

As a consequence of C19MC amplification, ETMRs upregulate several oncogenic and pluripotency proteins, including LIN28A, DNMT3B and MYCN, that confer a unique epigenetic signature reminiscent of nascent embryonic stem cells. In this review, we focus on the dysregulation of miRNAs in ETMR, the major pathogenic mechanism identified in this disease.

CONCLUSION

Despite the use of multi-modal therapeutic regimens, ETMR patients have dismal survival. Understanding the unique biology of these tumors has provided new insights towards novel therapeutic targets.

Histopathologic and Molecular Features of Central Nervous System Embryonal Tumors for Integrated Diagnosis Reporting

Embryonal tumors of the pediatric central nervous system are challenging clinically and diagnostically. These tumors are aggressive, and patients often have poor outcomes even with intense therapy. Proper tumor classification is essential to patient care, and this process has undergone significant changes with the World Health Organization recommending histopathologic and molecular features be integrated in diagnostic reporting. This has especially impacted the workup of embryonal tumors because molecular testing has resulted in the identification of clinically relevant tumor subgroups and new entities. This review summarizes recent developments and provides a framework to workup embryonal tumors in diagnostic practice.

Embryonal Tumors of the Central Nervous System: An Update

Embryonal tumors of the central nervous system (CNS) are rare, high-grade neoplasms predominantly affecting the pediatric population. Well-defined embryonal tumors include medulloblastoma, atypical teratoid/rhabdoid tumor, embryonal tumor with multilayered rosettes, C19MC-altered and embryonal tumor with multilayered rosettes, not otherwise specified, pineoblastoma, pituitary blastoma, CNS neuroblastoma, and ganglioneuroblastoma. Although their prognosis is nearly uniformly poor, the rapidly evolving understanding of their molecular biology contributes to diagnosis, prognosis, treatment, and clinical trial participation. Knowledge of current tumor stratification and diagnostic techniques will help pathologists guide care and preserve tissue for necessary or desired additional testing.

Embryonal tumor with multilayered rosettes, C19MC-altered (ETMR): a newly defined pediatric brain tumor

Embryonal tumor with multilayered rosettes (ETMR), C19MC-altered, is a newly defined and rare pediatric malignant tumor of the central nervous system (CNS) in the 2016 WHO Classification of Tumors of the Central Nervous System. Here we present two cases of ETMR with amplification of the C19MC locus at chromosome 19q13.42. Case 1 is a fifteen-year-old boy, who underwent gamma knife surgery two times three years ago, after presenting with seizures. Magnetic resonance imaging (MRI) identified a large mass in the left frontotemporal lobe. Case 2 is a three-year-old boy who underwent surgery for a right frontal lobe tumor followed by chemotherapy. Eight months later, MRI identified a recurrent tumor in the bilateral frontal lobe. Histologically, cases 1 and 2 exhibited a typical papillary/trabecular and a multilayered rosette pattern resembling medulloepithelioma (ME) and ependymoblastoma (EBL), respectively. Immunohistochemically, CD99, synaptophysin, vimentin, and LIN28A were positive in both cases. Most importantly, both cases displayed amplification in the C19MC locus at 19q13.42 in a fluorescence in situ hybridization (FISH) analysis.

Medulloepithelioma with heterologous osteoid component: a case report and review of literature

PURPOSE

Medulloepithelioma is a rare brain tumor that has been classified as embryonal tumor with multilayered rosettes (ETMR) if it harbors C19MC amplification. In rare instances, it shows evidence of heterologous differentiation.

METHODS

We report a case of a 10-year-old female who presented with headache, squint, and minimal left sided weakness of 1 week duration.

RESULTS

Microscopy revealed a small round blue cell tumor with focal glandular and tubular differentiation. In one focus, well-developed osteoid was identified. The tumor labeled with LIN28A immunostain.

CONCLUSIONS

Unusual features can be encountered in medulloepithelioma which should be in the differential diagnosis of CNS embryonal tumors. Full description of the case with review of the literature and comparison between cases with and without heterologous elements is presented.

Embryonal tumor with multilayered rosettes: illustrative case and review of the literature

BACKGROUND

Embryonal tumor with multilayered rosettes (ETMR) is a very rare entity and has seldom been reported. It has been newly defined tumor entity included in the latest update (revised fourth edition) of WHO 2016 Classification of Tumors of the Central Nervous System which portends a uniform dismal prognosis and survival even with the best of multimodality approaches.

ILLUSTRATIVE CASE

This report documents the presentation of a 2-year-old girl with voluminous intracranial ETMR in the right parieto-occipital region. We describe clinical diagnosis, histological aspects, radiological features, and current management of this very aggressive tumor.

CONCLUSION

Pediatric intracranial ETMR is a highly aggressive neoplasm, and it should be considered in the differential diagnosis of pediatric brain tumors.

Radiation for ETMR: Literature review and case series of patients treated with proton therapy

Background and purpose

Embryonal tumors with multilayered rosettes (ETMRs) are aggressive tumors that typically occur in young children. Radiation is often deferred or delayed for these patients due to late effects; proton therapy may mitigate some of these concerns. This study reviews the role of radiation in ETMR and describes initial results with proton therapy.

Materials and methods

Records of patients with embryonal tumor with abundant neuropil and true rosettes (ETANTR), medulloepithelioma (MEP), and ependymoblastoma (EPL) treated with proton therapy at our institution were retrospectively reviewed. A literature review of cases of CNS ETANTR, MEP, and EPL published since 1990 was also conducted.

Results

Seven patients were treated with proton therapy. Their median age at diagnosis was 33 months (range 10-57 months) and their median age at radiation start was 42 months (range 17-58 months). Their median overall survival (OS) was 16 months (range 8-64 months), with three patients surviving 36 months or longer. Five patients had disease progression prior to starting radiation; all 5 of these patients failed in the tumor bed. A search of the literature identified 204 cases of ETMR with a median OS of 10 months (range 0.03-161 months). Median OS of 18 long-term survivors (≥36 months) in the literature was 77 months (range 37-184 months). Of these 18 long-term survivors, 17 (94%) received radiotherapy as part of their initial treatment; 14 of them were treated with craniospinal irradiation.

Conclusions

Outcomes of patients with ETMR treated with proton therapy are encouraging compared to historical results. Further study of this rare tumor is warranted to better define the role of radiotherapy.

Year 1 in the Molecular Era of Pediatric Brain Tumor Diagnosis: Application of Universal Clinical Targeted Sequencing in an Unselected Cohort of Children

Purpose

Next-generation sequencing is gaining acceptance as a clinical tool to aid diagnosis and guide treatment of pediatric cancer. Prior pilot studies have evaluated the feasibility and utility of clinical genomic profiling in a subset of selected patients with brain tumors. Here, we report an unselected prospective cohort study to evaluate the clinical use of universal targeted sequencing in pediatric patients with brain tumors.

Methods

We applied a universal sequencing protocol for all tumors of the CNS undergoing diagnostic workup at Seattle Children’s Hospital during the study period of November 2015 to November 2016. All tumors were sequenced using the UW-OncoPlex platform, which is a multiplexed targeted deep gene sequencing panel that detects genetic alterations in 262 cancer-related genes performed in a College of American Pathologists–accredited Clinical Laboratory Improvements Amendments–certified laboratory.

Results

Eighty-eight patients underwent diagnostic evaluation during the study period, of which 85 tumors (95%) yielded sufficient DNA for sequencing, including 59 newly diagnosed and 26 relapsed. Clinically relevant genetic alterations were identified in 68 of 85 patients (80%). Of these, 57 (67%) had disease-defining or disease-modifying mutations, 44 (52%) had potentially targetable mutations, and 31 (36%) had mutations requiring germline follow-up. As of the last follow-up, seven patients had been prescribed targeted agents on the basis of sequencing results, and nine had confirmed deleterious germline mutations.

Conclusion

Clinically validated molecular profiling of pediatric brain tumors aids diagnosis and treatment of patients with a variety of high- and low-grade primary and relapsed pediatric brain tumors.

Rare Primary Central Nervous System Tumors Encountered in Pediatrics

As part of the special issue on Pediatric Neuro-Oncology, this article will focus on 4 of the rarer tumors in this spectrum, including atypical teratoid rhabdoid tumors, embryonal tumors with multilayered rosettes, choroid plexus tumors, and pleomorphic xanthoastrocytoma. Incidence and current understanding of the molecular pathogenesis of these tumors are discussed, and avenues of therapy both current and prospective are explored.

Embryonal tumor with multilayered rosettes of the fourth ventricle: case report

Embryonal tumor with multilayered rosettes (ETMR) is a recently described pathological entity. These primitive central nervous system tumors harbor amplification of the 19q13.42 locus and resultant overexpression of the LIN28A protein. Although the WHO currently recognizes 3 distinct histopathological entities-embryonal tumor with abundant neuropil and true rosettes (ETANTR), ependymoblastoma, and medulloepithelioma-recent studies indicate that these tumors have a common molecular profile and clinical course and that they are now classified as a single entity. Here the authors present a case of ETMR located in the fourth ventricle in a 12-month-old boy. The histopathology featured areas of neuropil-like stroma and highly cellular foci with characteristic multilayered rosettes. The authors discuss the clinical, radiological, and histopathological findings in this case and compare them with data in previously published cases in the literature. A review of studies assessing the molecular mechanisms underlying these tumors is also presented.

An Infant With Medulloepithelioma Successfully Treated by High-dose Chemotherapy Followed by Autologous Peripheral Blood Stem Cell Transplantation Without Radiotherapy

Medulloepithelioma of the central nervous system (CNS) is a rare primitive neuroectodermal tumor characterized by highly malignant behavior occurring in early childhood. Few cases have been reported and optimal management remains unknown. Here, we report a case of CNS medulloepithelioma successfully treated with high-dose chemotherapy (HDCTX) followed by autologous stem cell transplantation (auto-SCT) without radiotherapy. At the last follow-up, 3.0 years after onset, the patient was alive with no sign of relapse and normal development. To the best of our knowledge, this is the first reported case of long-term survival of CNS medulloepithelioma treated by HDCTX/auto-PBSCT without radiotherapy.

Comparative integrated molecular analysis of intraocular medulloepitheliomas and central nervous system embryonal tumors with multilayered rosettes confirms that they are distinct nosologic entities

Intraocular medulloepithelioma (IO MEPL) is an uncommon embryonal neuroepithelial neoplasm of the eye. These ocular neoplasms have been compared with intracranial medulloepitheliomas or other histologic variants of CNS embryonal tumor with multilayered rosettes (CNS ETMR) due to their morphological mimicry. We performed comprehensive molecular analysis to explore the histogenetic and biologic relationships between 22 IO MEPL and 68 CNS ETMR. Routinely prepared paraffin-embedded samples were assessed for genome-wide methylation profiles using the Illumina Methylation 450k BeadChip array. We identified strong cytogenetic and epigenetic differences between ocular neoplasms and CNS ETMR. None of the IO MEPL cases displayed the ETMR-specific amplification of the C19MC locus. Instead, cytogenetic analysis of the IO MEPL showed numerous copy number aberrations which involved either whole chromosomes or chromosomal arms; recurrent aberrations in these tumors affected chromosomes 1p, 4, 8 and 16p. DNA methylation patterns were also strikingly different between these two tumor entities, suggesting that they do not share common origins and biological behaviors. Comparative cluster analysis of 198 pediatric CNS tumors and 22 IO MEPL revealed a clear demarcation of the CNS ETMR and IO MEPL profiles from other CNS entities. In conclusion, although IO MEPL shares some histopathological features with CNS ETMR, they manifest striking molecular diversity at the cytogenetic and epigenetic levels. Consequently they deserve a separate nosologic designation in future tumor classifications, where CNS MEPL could be designated as a histological variant of CNS ETMR.

Intraocular Medulloepitheliomas and Embryonal Tumors With Multilayered Rosettes of the Brain: Comparative Roles of LIN28A and C19MC

PURPOSE

To compare immunohistochemical and genetic overlaps and differences between intraocular medulloepitheliomas and embryonal tumors with multilayered rosettes of the brain.

DESIGN

Retrospective histopathologic, immunohistochemical, and genetic analysis of 20 intraocular medulloepitheliomas.

METHODS

(1) Review of clinical data and hematoxylin-eosin-stained sections with (2) immunohistochemical staining of paraffin sections using a polyclonal antibody against the protein LIN28A, and (3) fluorescence in situ hybridization (FISH) testing for the amplification of the genetic locus 19q13.42 involving the C19MC cluster of miRNA. Ten retinoblastomas served as controls and to determine the specificity of these biomarkers for intraocular medulloepitheliomas.

RESULTS

Nineteen of the 20 intraocular medulloepitheliomas were either diffusely or focally LIN28A positive (weak, moderate, or strong). The most intense positivity correlated with aggressive behavior such as intraocular tissue invasion or extraocular extension. None of the cases studied by FISH harbored an amplicon for C19MC. The 10 retinoblastomas were LIN28A and C19MC negative.

CONCLUSION

LIN28A has a putative role in oncogenesis and is found only in embryonic cells and malignancies. Intraocular medulloepitheliomas and embryonal tumors with multilayered rosettes of the brain both display LIN28A positivity. Only the latter, however, display amplification of the 19q13.42 locus involving C19MC, implying that other causative factors are at play in intraocular medulloepitheliomas. More aggressive tumor behavior within the eye can be partially predicted by LIN28A staining intensity.

MicroRNAs in pediatric central nervous system embryonal neoplasms: the known unknown

MicroRNAs (miRNAs) are endogenous short non-coding RNAs that repress post-transcriptional regulation of gene expression, while embryonal central nervous system tumors are the foremost cause of mortality in children suffering from a neoplasm. MiRNAs and their regulatory mechanisms are new to understand, while pediatric CNS tumors are difficult to comprehend. Therefore, identification of the link between them composes a major scientific challenge. The present study, reviewed the current knowledge on the role of miRNA in pediatric CNS embryonal tumors, attempting to collect the existing information in one piece of work that could ideally be used as a guide for future reference and research.

Practical molecular pathology and histopathology of embryonal tumors

There have been significant improvements in understanding of embryonal tumors of the central nervous system (CNS) in recent years. These advances are most likely to influence the diagnostic algorithms and methodology currently proposed by the World Health Organization (WHO) classification scheme. Molecular evidence suggests that the tumors presumed to be specific entities within the CNS/primitive neuroectodermal tumors spectrum are likely to be reclassified. All these developments compel reassessing current status and expectations from the upcoming WHO classification efforts. This review provides a synopsis of current developments and a practical algorithm for the work-up of these tumors in practice.

Embryonal tumor with abundant neuropil and true rosettes with only one structure suggestive of an ependymoblastic rosette

Embryonal tumor with abundant neuropil and true rosettes (ETANTR) is a very aggressive embryonal central nervous system (CNS) tumor, histologically featuring ependymoblastic rosettes and neuronal differentiation in a neuropil-like background. 19q13.42 amplification was identified in ETANTR and epndymoblastoma, suggesting that these tumors constitute a single entity, called embryonal tumor with multilayered rosettes (ETMR). Here, we report a case involving a 2-year-old boy with a pontine embryonal tumor composed of clusters of poorly differentiated neuroepithelial cells, and smaller neuroblastic/neurocytic cells in a fibrillary and paucicellular neuropil-like matrix, where clear ependymoblastic rosettes were not detected but only one structure suggestive of an ependymoblastic multilayered rosette was found. Fluorescence in situ hybridazation analysis revealed 19q13.42 amplification, supporting the diagnosis of ETANTR. This report indicates that rare ependymoblasic rosettes found in embryonal tumors, which are otherwise CNS primitive neuroectodermal tumors or medulloblastomas, are significant for considering the examination of 19q13.42 amplification to confirm the diagnosis of ETMR.

CNS-PNETs with C19MC amplification and/or LIN28 expression comprise a distinct histogenetic diagnostic and therapeutic entity

Amplification of the C19MC oncogenic miRNA cluster and high LIN28 expression has been linked to a distinctly aggressive group of cerebral CNS-PNETs (group 1 CNS-PNETs) arising in young children. In this study, we sought to evaluate the diagnostic specificity of C19MC and LIN28, and the clinical and biological spectra of C19MC amplified and/or LIN28+ CNS-PNETs. We interrogated 450 pediatric brain tumors using FISH and IHC analyses and demonstrate that C19MC alteration is restricted to a sub-group of CNS-PNETs with high LIN28 expression; however, LIN28 immunopositivity was not exclusive to CNS-PNETs but was also detected in a proportion of other malignant pediatric brain tumors including rhabdoid brain tumors and malignant gliomas. C19MC amplified/LIN28+ group 1 CNS-PNETs arose predominantly in children <4 years old; a majority arose in the cerebrum but 24 % (13/54) of tumors had extra-cerebral origins. Notably, group 1 CNS-PNETs encompassed several histologic classes including embryonal tumor with abundant neuropil and true rosettes (ETANTR), medulloepithelioma, ependymoblastoma and CNS-PNETs with variable differentiation. Strikingly, gene expression and methylation profiling analyses revealed a common molecular signature enriched for primitive neural features, high LIN28/LIN28B and DNMT3B expression for all group 1 CNS-PNETs regardless of location or tumor histology. Our collective findings suggest that current known histologic categories of CNS-PNETs which include ETANTRs, medulloepitheliomas, ependymoblastomas in various CNS locations, comprise a common molecular and diagnostic entity and identify inhibitors of the LIN28/let7/PI3K/mTOR axis and DNMT3B as promising therapeutics for this distinct histogenetic entity.

Embryonal tumor with abundant neuropil and true rosettes (ETANTR), ependymoblastoma, and medulloepithelioma share molecular similarity and comprise a single clinicopathological entity

Three histological variants are known within the family of embryonal rosette-forming neuroepithelial brain tumors. These include embryonal tumor with abundant neuropil and true rosettes (ETANTR), ependymoblastoma (EBL), and medulloepithelioma (MEPL). In this study, we performed a comprehensive clinical, pathological, and molecular analysis of 97 cases of these rare brain neoplasms, including genome-wide DNA methylation and copy number profiling of 41 tumors. We identified uniform molecular signatures in all tumors irrespective of histological patterns, indicating that ETANTR, EBL, and MEPL comprise a single biological entity. As such, future WHO classification schemes should consider lumping these variants into a single diagnostic category, such as embryonal tumor with multilayered rosettes (ETMR). We recommend combined LIN28A immunohistochemistry and FISH analysis of the 19q13.42 locus for molecular diagnosis of this tumor category. Recognition of this distinct pediatric brain tumor entity based on the fact that the three histological variants are molecularly and clinically uniform will help to distinguish ETMR from other embryonal CNS tumors and to better understand the biology of these highly aggressive and therapy-resistant pediatric CNS malignancies, possibly leading to alternate treatment strategies.

Significance and therapeutic value of miRNAs in embryonal neural tumors

Embryonal tumors of the nervous system are the leading cause of childhood cancer-related morbidity and mortality. Medulloblastoma, supratentorial primitive neuroectodermal tumors, atypical teratoid/rhabdoid tumor and neuroblastoma account for more than 20% of childhood malignancies and typify the current neural embryonal tumor model in pediatric oncology. Mechanisms driving the formation of these tumors point towards impaired differentiation of neuronal and neuron-associated cells during the development of the nervous system as an important factor. The importance of microRNAs (miRNAs) for proper embryonic cell function has been confirmed and their aberrant expressions have been linked to tumor development. The role of miRNAs in controlling essential regulators of key pathways implicated in tumor development makes their use in diagnostics a powerful tool to be used for early detection of cancer, risk assessment and prognosis, as well as for the design of innovative therapeutic strategies. In this review we focus on the significance of miRNAs involved in the biology of embryonal neural tumors, delineate their clinical significance and discuss their potential as a novel therapeutic target.

A novel C19MC amplified cell line links Lin28/let-7 to mTOR signaling in embryonal tumor with multilayered rosettes

BACKGROUND

Embryonal tumor with multilayered rosettes (ETMR) is an aggressive central nervous system primitive neuroectodermal tumor (CNS-PNET) variant. ETMRs have distinctive histology, amplification of the chromosome 19 microRNA cluster (C19MC) at chr19q13.41-42, expression of the RNA binding protein Lin28, and dismal prognosis. Functional and therapeutic studies of ETMR have been limited by a lack of model systems.

METHODS

We have established a first cell line, BT183, from a case of ETMR and characterized its molecular and cellular features. LIN28 knockdown was performed in BT183 to examine the potential role of Lin28 in regulating signaling pathway gene expression in ETMR. Cell line findings were corroborated with immunohistochemical studies in ETMR tissues. A drug screen of 73 compounds was performed to identify potential therapeutic targets.

RESULTS

The BT183 line maintains C19MC amplification, expresses C19MC-encoded microRNAs, and is tumor initiating. ETMRs, including BT183, have high LIN28 expression and low let-7 miRNA expression, and show evidence of mTOR pathway activation. LIN28 knockdown increases let-7 expression and decreases expression of IGF/PI3K/mTOR pathway components. Pharmacologic inhibition of the mTOR pathway reduces BT183 cell viability.

CONCLUSIONS

BT183 retains key genetic and histologic features of ETMR. In ETMR, Lin28 is not only a diagnostic marker but also a regulator of genes involved in growth and metabolism. Our findings indicate that inhibitors of the IGF/PI3K/mTOR pathway may be promising novel therapies for these fatal embryonal tumors. As the first patient-derived cell line of these rare tumors, BT183 is an important, unique reagent for investigating ETMR biology and therapeutics.

Embryonal tumor with abundant neuropil and true rosettes: a systematic literature review and report of 2 new cases

Embryonal tumor with abundant neuropil and true rosettes has been recently defined as a distinct central nervous system embryonal neoplasm, although it was initially regarded as a subtype of central nervous system primitive neuroectodermal tumor. To date 70 cases have been reported. We have performed a literature review and we present 2 new cases. Analysis of the reported data revealed that radiotherapy, tumor excision and high-dose adjuvant chemotherapy with sequential autologous hematopoietic stem cell rescue have a prognostic significance.

Post-chemotherapy maturation in supratentorial primitive neuroectodermal tumors

Maturation in central nervous system embryonal tumors is an uncommon phenomenon that is mainly reported in the context of specific histological subgroups of medulloblastoma. In this report we describe two cases of histological maturation in patients with supratentorial primitive neuroectodermal tumor with strikingly different outcomes. We discuss the potential impact of such findings on treatment and outcome.

Embryonal tumor with abundant neuropil and true rosettes: an autopsy case-based update and review of the literature

INTRODUCTION

Embryonal tumor with abundant neuropil and true rosettes (ETANTR) is a rare subtype of primitive neuroectodermal tumors first reported in 2000. It is rare among the group of embryonal central nervous system tumors with approximately 50 reported cases. ETANTR has been suggested to be a separate entity among this group of tumors.

CASE REPORT

Herein, we present only the second autopsy case of ETANTR, which occurred in a 17-month-old boy, and was located in the brainstem. The tumor was inoperable, and despite chemotherapy, the child died 3 months after initial hospitalization. A brain only autopsy was performed.

DISCUSSION

Neuropathological and neuroimaging examinations suggest ETANTR grew by expansion rather than invasion distorting anatomical structures of the posterior fossa. We suggest that the characteristic histopathological picture of the tumor is the result of multifocal and dispersed germinative activity surrounded by mature neuropil-like areas.

CONCLUSION

ETANTR is a pediatric tumor occurring in children under 4 with a significantly poor prognosis with more cases and research required to characterize this rare embryonal tumor.

While at Rome miRNA and TRAIL do whatever BCR-ABL commands to do

It is a well-acclaimed fact that proteins expressed as a consequence of oncogenic fusions, mutations or amplifications can facilitate ectopic protein-protein interactions that re-wire signal dissemination pathways, in a manner that escalates malignancy. BCR-ABL-mediated signal transduction cascades in leukemic cells are assembled and modulated by a finely controlled network of protein-protein interactions, mediated by characteristic signaling domains and their respective binding motifs. BCR-ABL functions in a cell context-specific and cell type-specific manner to integrate signals that affect uncontrolled cellular proliferation. In this review, we draw attention to the recent progress made in outlining resistance against TRAIL-mediated apoptosis and diametrically opposed roles of miRNAs in BCR-ABL-positive leukemic cells. BCR-ABL governs carcinogenesis through well-organized web of antiapoptotic proteins and over-expressed oncomirs which target death receptors and pro-apoptotic genes. Set of oncomirs which inversely correlate with expression of TRAIL via suppression of SMAD is an important dimension which is gradually gaining attention of the researchers. Contrary to this, some current findings show a new role of BCR-ABL in nucleus with spotlight on apoptosis. It seems obvious that genetic heterogeneity of leukemias poses therapeutic challenges, and pharmacological agents that target components of the cancer promoting nano-machinery still need broad experimental validation to be considered competent as a component of the therapeutic arsenal for this group of diseases. Rapidly developing technologies are empowering us to explain the molecular "nature" of a patient and/or tumor and with this integration of personalized medicine, with maximized efficacy, cost effectiveness will hopefully improve survival chances of the patient.

LIN28A immunoreactivity is a potent diagnostic marker of embryonal tumor with multilayered rosettes (ETMR)

Embryonal tumor with multilayered rosettes (ETMR, previously known as ETANTR) is a highly aggressive embryonal CNS tumor, which almost exclusively affects infants and is associated with a dismal prognosis. Accurate diagnosis is of critical clinical importance because of its poor response to current treatment protocols and its distinct biology. Amplification of the miRNA cluster at 19q13.42 has been identified previously as a genetic hallmark for ETMR, but an immunohistochemistry-based assay for clinical routine diagnostics [such as INI-1 for atypical teratoid rhabdoid tumor (AT/RT)] is still lacking. In this study, we screened for an ETMR-specific marker using a gene-expression profiling dataset of more than 1,400 brain tumors and identified LIN28A as a highly specific marker for ETMR. The encoded protein binds small RNA and has been implicated in stem cell pluripotency, metabolism and tumorigenesis. Using an LIN28A specific antibody, we carried out immunohistochemical analysis of LIN28A in more than 800 childhood brain-tumor samples and confirmed its high specificity for ETMR. Strong LIN28A immunoexpression was found in all 37 ETMR samples tested, whereas focal reactivity was only present in a small (6/50) proportion of AT/RT samples. All other pediatric brain tumors were completely LIN28A-negative. In summary, we established LIN28A immunohistochemistry as a highly sensitive and specific, rapid, inexpensive diagnostic tool for routine pathological verification of ETMR.

Molecular markers in pediatric neuro-oncology

Pediatric molecular neuro-oncology is a fast developing field. A multitude of molecular profiling studies in recent years has unveiled a number of genetic abnormalities unique to pediatric brain tumors. It has now become clear that brain tumors that arise in children have distinct pathogenesis and biology, compared with their adult counterparts, even for those with indistinguishable histopathology. Some of the molecular features are so specific to a particular type of tumors, such as the presence of the KIAA1549-BRAF fusion gene for pilocytic astrocytomas or SMARCB1 mutations for atypical teratoid/rhabdoid tumors, that they could practically serve as a diagnostic marker on their own. Expression profiling has resolved the existence of 4 molecular subgroups in medulloblastomas, which positively translated into improved prognostication for the patients. The currently available molecular markers, however, do not cover all tumors even within a single tumor entity. The molecular pathogenesis of a large number of pediatric brain tumors is still unaccounted for, and the hierarchy of tumors is likely to be more complex and intricate than currently acknowledged. One of the main tasks of future molecular analyses in pediatric neuro-oncology, including the ongoing genome sequencing efforts, is to elucidate the biological basis of those orphan tumors. The ultimate goal of molecular diagnostics is to accurately predict the clinical and biological behavior of any tumor by means of their molecular characteristics, which is hoped to eventually pave the way for individualized treatment.

Exosome-delivered microRNAs of "chromosome 19 microRNA cluster" as immunomodulators in pregnancy and tumorigenesis

Background

Structural rearrangements of chromosomal band 19q13 are a non-random cytogenetic abnormality in thyroid adenomas and adenomatous goiters and lead to an expression of miRNAs of the chromosome 19 microRNA cluster C19MC. Normally, expression of these miRNAs is silenced except for embryonic stem cells and the placenta where they represent the majority of miRNAs not only in the trophoblast but also in exosomes derived from it.

Presentation of the hypothesis

We have advanced the hypothesis that as part of the feto-maternal communication miRNAs of C19MC serve immunomodulatory functions in the placenta and confer a growth advantage to thyroid nodules by protecting them against autoimmune attacks. More precisely, the exosomes containing these miRNAs may specifically target immune cells in their local environment as well as systemically by transferring their cargo to recipient cells. Within these target cells the transferred miRNAs can interact with mRNAs of the recipient cells thereby suppressing their immune-specific functions.

Testing the hypothesis

Experiments used to demonstrate the immunomodulatory capacity of placenta-derived exosomes can be modified by transfecting the target cells with those miRNAs of C19MC represented in placental exosomes.

Implications of the hypothesis

Mimics of C19MC-derived miRNAs might develop to useful drug candidates for the treatment of autoimmune disease as e.g. rheumatoid arthritis and Sjögren’s syndrome and for the prevention of transplant rejection. In case of tumor entities with elevated expression of C19MC miRNAs these miRNAs may be interesting targets for treatment with appropriate antagonists.