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.     

Embryonal tumor with abundant neuropil and true rosettes (ETANTR) with a focal amplification at chromosome 19q13.42 locus: Further evidence of two new instances in China

Recently, the term “embryonal tumor with multilayered rosettes” (ETMR), including embryonal tumor with abundant neuropil and true rosettes (ETANTR) and ependymoblastoma (EBL) as a distinct tumor entity, has become an important topic of discussion for neuropathologists since the discovery of a unique genomic alteration in 2009. Here, we contribute two new East Asian instances of ETANTR in a 29‐month‐old boy who underwent subtotal resection of a large tumor in the bilateral parieto‐occipital lobes and a 4‐year‐old boy who underwent subtotal resection of the right midpontine neoplasm. Both tumors showed a typical histopathological pattern of hypercellular clusters of undifferentiated small cells and ependymoblastic rosettes admixed with paucicellular neuropil‐like zones indicative for ETANTR. Rare Homer‐Wright neuroblastic rosettes and papillary pseudorosettes, as well as enlarged lumina with mucinous material, were also observed. Immunohistological studies revealed that tumor cells in hypercellular and paucicellular zones were diffusely positive for microtubule‐associated protein 2; ependymoblastic rosette cells stained with epithelial membrane antigen at the luminal membrane and exhibiting strong immunoreactivity with p53 protein. β‐Catenin and Nestin were frequently detected in the hypercellular zones as well as in the ependymoblastic rosettes. Fluorescence in situ hypribization analysis revealed that both cases contained a unique focal amplification at the 19q13.42 chromosome locus and chromosome 2 polysomy. A new WHO classification of tumors of the CNS should be considered for these neoplasms with unique focal amplification at the 19q13.42 chromosome locus, based on the clinicopathological and molecular features of ETANTR that are distinct and reproducibly recognizable.     

Embryonal tumor with multilayered rosettes: Two case reports with a review of the literature

Embryonal tumor with multilayered rosettes (ETMR) is a well-recognized histopathological variant of primitive neurectodermal tumors of the central nervous system. This tumor depicts histopathological features that are common to both ependymoblastoma (EBL) and neuroblastoma. Here we report two pediatric cases of ETMR, one exhibiting dominant neuronal differentiation and the other with dominant glial differentiation, thereby expanding the previously known pathologic spectrum. The varying histological features, common morphologic diagnostic difficulties as well as variable postsurgical survival of this entity compared to similar embryonal tumors are highlighted.     

Focal genomic amplification at 19q13.42 comprises a powerful diagnostic marker for embryonal tumors with ependymoblastic rosettes

Ependymoblastoma (EBL) and embryonal tumor with abundant neuropil and true rosettes (ETANTR) are very aggressive embryonal neoplasms characterized by the presence of ependymoblastic multilayered rosettes typically occurring in children below 6 years of age. It has not been established whether these two tumors really comprise distinct entities. Earlier, using array-CGH, we identified a unique focal amplification at 19q13.42 in a case of ETANTR. In the present study, we investigated this locus by fluorescence in situ hybridization in 41 tumors, which had morphologically been diagnosed as EBL or ETANTR. Strikingly, FISH analysis revealed 19q13.42 amplifications in 37/40 samples (93%). Among tumors harboring the amplification, 19 samples were identified as ETANTR and 18 as EBL. The three remaining tumors showed a polysomy of chromosome 19. Analysis of recurrent/metastatic tumors (n = 7) showed that the proportion of nuclei carrying the amplification was increased (up to 80–100% of nuclei) in comparison to the corresponding primary tumors. In conclusion, we have identified a hallmark cytogenetic aberration occurring in virtually all embryonal brain tumors with ependymoblastic rosettes suggesting that ETANTR and EBL comprise a single biological entity. FISH analysis of the 19q13.42 locus is a very promising diagnostic tool to identify a subset of primitive neuroectodermal tumors with distinct morphology, biology, and clinical behavior.     

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.     

Novel genomic amplification targeting the microRNA cluster at 19q13.42 in a pediatric embryonal tumor with abundant neuropil and true rosettes

Embryonal tumors with abundant neuropil and true rosettes (ETANTR) comprise a rare variant of embryonal brain tumors usually occurring in infants. Only 13 cases have been reported in the literature to date and little is known about the molecular pathogenesis of these tumors. Here, we describe a case of ETANTR in a 2-year-old girl presenting with a large tumor in the vermis of the cerebellum. Histological examination showed clusters of small-undifferentiated cells including ependymoblastic-like rosettes admixed with large fibrillar and paucicellular neuropil-like areas indicative for ETANTR. Genomic imbalances were detected by using array-based comparative genomic hybridization. In addition to trisomy of chromosome 2, which has been previously described in ETANTR, array-CGH revealed high-level genomic amplification of 0.89 Mb at chromosome band 19q13.42 covering a microRNA cluster and several protein-coding genes. This aberration has not been described in any other brain tumor to date, indicating a specific aberration in ETANTR. MicroRNAs contained in the microRNA cluster at 19q13.42 including oncomirs miRNA-372 and miRNA-373 were highly up-regulated in the tumor when compared to normal cerebellum or whole brain. In summary, this is the first report on a potentially specific genetic aberration in ETANTR, supporting the hypothesis of a distinct tumor entity. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

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.     

Embryonal tumor with abundant neuropil and true rosettes: a report of three cases of a rare tumor,with an unusual case showing rhabdomyoblastic and melanocytic differentiation

Embryonal tumor with abundant neuropil and true rosettes (ETANTR) is an increasingly recognized entity that belongs to the family of embryonal tumors of the CNS. The authors present three cases of this rare tumor that were encountered at King Hussein Cancer Center, Amman, Jordan. Discussion of the clinicopathological findings is presented along with a recent literature review. Sixteen‐, 57‐ and 30‐month‐old children presented with tumors located in the pineal gland, the right fronto‐ parieto‐temporal region and the cerebellum, respectively. The findings of hypocellular neuropil as well as the characteristic ependymoblastic rosettes were seen. In addition the third case showed an abnormal combination of patterns including melanocytic and rhabdomyoblastic differentiation. The tumors stained positively for synaptophysin in the neuropil and small cell component, while the ependymoblastic rosettes stained for vimentin only. Epithelial membrane antigen and CD99 were negative in all components. One of the cases showed tetraploidy of chromosome 2. All cases exhibited an aggressive course. This is a rare and recently recognized tumor with dismal outcome, and reporting of additional new cases should help in gaining more knowledge about it.     

TP53, β-Catenin and c-myc/N-myc status in embryonal tumours with ependymoblastic rosettes

M. Gessi, A. zur Muehlen, L. Lauriola, M. P. Gardiman, F. Giangaspero and T. Pietsch (2011) Neuropathology and Applied Neurobiology 37, 406–413
TP53, β‐Catenin and c‐myc/N‐myc status in embryonal tumours with ependymoblastic rosettes Background: The primitive neuroectodermal tumours of central nervous system (CNS‐PNET) are a heterogeneous group of neoplasms, occurring in the CNS and composed of undifferentiated or poorly differentiated neuroepithelial cells which may display divergent differentiation along neuronal, astrocytic and ependymal lines. The WHO classification includes in this group of tumours also ependymoblastomas and medulloepitheliomas. Several groups have reported examples of CNS‐PNET with combined histological features of ependymoblastoma and neuroblastoma, defined as ‘embryonal tumour with abundant neuropil and true rosettes’. The presence of the amplification of chromosome region 19q13.42, common in both ependymoblastoma and embryonal tumour with abundant neuropil and true rosettes, suggests that they represent a histological spectrum of a single biological entity. Methods: We examined 24 cases of ependymoblastoma/embryonal tumour with abundant neuropil and true rosettes (EPBL/ETANTR) for the presence of mutations of TP53 and β‐Catenin and for amplification of c‐myc/N‐myc. Results: The single strand conformation polymorphism‐mutational screening did not identify any mutation in exons 5 to 8 of the TP53 gene. However, we found a point mutation affecting codon 34 (GGA→GTA) of β‐Catenin gene resulting in a Glycine → Valine substitution. No cases presented c‐myc/N‐myc amplification. Conclusions: EPBL/ETANTRs show molecular features different from other CNS‐PNET and medulloblastomas. The presence of alterations in the β‐Catenin/WNT pathway seems to be noteworthy due to the close relationship between this pathway and miR‐520g encoded in chromosome 19q13.42 region amplified in these tumours.     

Epigenetic dysregulation: a novel pathway of oncogenesis in pediatric brain tumors

A remarkably large number of “epigenetic regulators” have been recently identified to be altered in cancers and a rapidly expanding body of literature points to “epigenetic addiction” (an aberrant epigenetic state to which a tumor is addicted) as a new previously unsuspected mechanism of oncogenesis. Although mutations are also found in canonical signaling pathway genes, we and others identified chromatin-associated proteins to be more commonly altered by somatic alterations than any other class of oncoprotein in several subgroups of childhood high-grade brain tumors. Furthermore, as these childhood malignancies carry fewer non-synonymous somatic mutations per case in contrast to most adult cancers, these mutations are likely drivers in these tumors. Herein, we will use as examples of this novel hallmark of oncogenesis high-grade astrocytomas, including glioblastoma, and a subgroup of embryonal tumors, embryonal tumor with multilayered rosettes (ETMR) to describe the novel molecular defects uncovered in these deadly tumors. We will further discuss evidence for their profound effects on the epigenome. The relative genetic simplicity of these tumors promises general insights into how mutations in the chromatin machinery modify downstream epigenetic signatures to drive transformation, and how to target this plastic genetic/epigenetic interface.     

Embryonal tumor with abundant neuropil and true rosettes (ETANTR): a new distinctive variety of pediatric PNET: a case-based update

Background  

Embryonal central nervous system (CNS) tumors are currently classified into three types: medulloblastoma, atypical rhabdoid/teratoid tumors, and primitive neuroectodermal tumor (PNET). A distinctive subtype of PNET called “embryonal tumor with abundant neuropil and true rosettes” (ETANTR) was reported in 2000.     

Combined morphological,immunohistochemical and genetic analyses of medulloepithelioma in the posterior cranial fossa

Medulloepithelioma is a rare and highly malignant primitive neuroectodermal tumor that usually occurs in childhood. The diagnosis of this entity required only morphological analysis until the World Health Organization classification of central nervous system (CNS) tumors was revised, and now genetic analysis is necessary. We report a case of medulloepithelioma in the posterior cranial fossa that was diagnosed by both morphological and genetic analyses based on this classification. A 10‐month‐old girl was admitted to our hospital with consciousness disturbance and vomiting. Neuroimaging revealed a partially calcified mass and cyst formation in the posterior cranial fossa. Partial resection of the tumor was performed and histological findings revealed multilayered rosettes with LIN28A staining, but genetic analysis showed no amplification of the C19MC microRNA cluster at 19q14.32. Therefore, we diagnosed the tumor as medulloepithelioma belonging to other CNS embryonal tumors. The patient was immediately treated with systemic high‐dose chemotherapy. Follow‐up neuroimaging 10 months later showed no signs of recurrence. Medulloepitheliomas are difficult to diagnose by routine HE staining and require combined morphological, immunohistochemical and genetic analyses to provide an accurate diagnosis.     

Comparative genomic hybridization in central and peripheral nervous system tumors of childhood and adolescence

Brain tumors amount to less than 2% of all malignant neoplasms. However, they account for approximately 20% of all childhood cancers and are the leading cause of cancer mortality among children. Recently, enormous progress has been achieved in the field of pediatric neuro-oncology regarding the classification of children's brain tumors, as well as the understanding of the genetic events involved in their pathogenesis; thus leading to an emerging role of molecular diagnostic approaches using novel tools. Comparative genomic hybridization (CGH) is a technique that has revolutionized cytogenetic knowledge in the past decade. It permits the detection of chromosomal copy number changes without the need for cell culturing and gives a global overview of chromosomal gains and losses throughout the whole genome of a tumor. A survey of CGH-related publications on central and peripheral nervous system tumors in the pediatric and adolescent population revealed 884 cases. The CNS tumor groups most frequently examined by CGH were embryonal tumors (268 cases/30.3%) and ependymomas (241/27.2%), followed by astrocytic (163/18.4%), peripheral nerve (73/8.2%), choroid plexus tumors (56/6.3%), and craniopharyngiomas (38/4.3%). The most common CNS tumor entities were medulloblastomas (238/26.9%), classic ependymomas (160/18.1%), anaplastic ependymomas (70/7.9%), pleomorphic xanthoastrocytomas (53/6.0%), and pilocytic astrocytomas (50/5.6%). This article provides a short review of the CGH technique and its pitfalls, summarizes the current CGH-related data on pediatric brain tumors and muses on the future of CGH.     

Embryonal tumor with abundant neuropil and true rosettes: Morphological,immunohistochemical, ultrastructural and molecular study of a case showing features of medulloepithelioma and areas of mesenchymal and epithelial differentiation

Embryonal tumors are a group of malignant neoplasms that most commonly affect the pediatric population. Embryonal tumor with abundant neuropil and true rosettes is a recently recognized rare tumor. It is composed of neurocytes and undifferentiated neuroepithelial cells arranged in clusters, cords and several types of rosettes in a prominent neuropil‐rich background. We describe a new case of this tumor. The patient, a 24‐month‐old female infant, was referred to the Meyer Children's Hospital with a history of right brachio‐crural deficit associated with occasional episodes of headache and vomiting. Computed tomography scan and MRI revealed a large bihemispheric mass. The patient underwent two consecutive surgeries. The resultant surgical resection of the tumor was macroscopically complete. The postoperative period was uneventful. On light microscopy the tumor showed a composite morphology: embryonal tumor with abundant neuropil and true rosettes (specimen from the first surgery); medulloepithelioma with mesenchymal and epithelial areas (specimen from the second surgery). The immunohistochemistry evidenced the heterogeneous (neuronal, mesenchymal and epithelial) immunoprofile of tumoral cells. By real‐time polymerase chain reaction (RT‐PCR), the PTEN gene expression in the tumor was lower than in the five non‐neoplastic brain tissues used as control. Mutation analysis did not show any variation in INI‐1 and PTEN sequence while P53 analysis showed the presence of homozygote P72R variation. Fluorescent in situ hybridization analysis showed polysomy of chromosome 2 while amplification of N‐MYC was not detected. Owing to the rarity of embryonal tumor with abundant neuropil and true rosettes, each new case should be recorded to produce a better clinical, pathological and molecular characterization of this lesion.     

Distinctive pattern of cannabinoid receptor type II (CB2) expression in adult and pediatric brain tumors

The efficacy of cannabinoids against high-grade glioma in animal models, mediated by two specific receptors, CB1 and CB2, raised promises for targeted treatment of the most frequent and malignant primary brain tumors. Unlike the abundantly expressed CB1, the CB2 receptor shows a restricted distribution in normal brain. Although brain tumors constitute the second most common malignancy in children and the prevalence of histological types of brain tumors vary significantly between the adult and pediatric populations, cannabinoid receptor expression in pediatric tumors remains unknown. In the present study, we compared the expression of the CB2 receptor in paraffin-embedded sections from primary brain tumors of adult and pediatric patients. Most glioblastomas expressed very high levels of CB2 receptors and the expression correlated with tumor grade. Interestingly, some benign pediatric astrocytic tumors, such as subependymal giant cell astrocytoma (SEGA), which may occasionally cause mortality owing to progressive growth, also displayed high CB2 immunoreactivity. The high levels of CB2 expression would predestine those tumors to be vulnerable to cannabinoid treatment. In contrast, all examined cases of embryonal tumors (medulloblastoma and S-PNET), the most frequently diagnosed malignant brain tumors in childhood, showed no or trace CB2 immunoreactivity. Our results suggest that the CB2 receptor expression depends primarily on the histopathological origin of the brain tumor cells and differentiation state, reflecting the tumor grade.     

Pediatric central nervous system tumors: review of a single Portuguese institution

Introduction

Despite being the second most frequent tumor in children, pediatric central nervous system (CNS) tumors are rare, and the published European epidemiological data is limited. Our goal is to present the first surgical series of pediatric CNS tumors in Portugal and to review other similar worldwide series.

Methods

Retrospective review of all patients younger than 19 years old, operated to a CNS tumor in the Neurosurgery Department at Hospital de Santa Maria (Lisbon, Portugal) between January 2004 and December 2014. Demographic data, tumor location, clinical data, histopathology, and surgical treatment were analyzed and compared to surgical series of pediatric CNS tumors published in PubMed indexed journals over the last 20 years.

Results

We performed 253 surgeries in 215 patients, with a male:female ratio of 1.2:1 and a mean age of 9.2 years old. Primary brain tumors accounted for 95 % of all tumors and had more often a supratentorial location. Tumors of neuroepithelial tissue, particularly astrocytic tumors, embryonal tumors, neuronal and mixed neuronal-glial tumors, and oligodendrogliomas accounted for 81 % of cases. A gross-total resection was achieved in most cases. There was no mortality, and the overall morbidity was low.

Conclusions

The demography, topography, and clinical presentation of the tumors and the surgical results of this series are comparable to other European ones. We found a higher incidence of neuronal and mixed neuronal-glial tumors and oligodendrogliomas and a slight lower incidence of ependymomas. Our results should encourage further national multi-institutional studies to better characterize these tumors in the pediatric population.