Nonrandom gain of chromosome 7 in central neurocytoma: a chromosomal analysis and fluorescence in situ hybridization study

Central neurocytoma exhibits radial glial cell signatures with FGFR3 hypomethylation and overexpression

We explored the genomic events underlying central neurocytoma (CN), a rare neoplasm of the central nervous system, via multiomics approaches, including whole-exome sequencing, bulk and single-nuclei RNA sequencing, and methylation sequencing. We identified FGFR3 hypomethylation leading to FGFR3 overexpression as a major event in the ontogeny of CN that affects crucial downstream events, such as aberrant PI3K-AKT activity and neuronal development pathways. Furthermore, we found similarities between CN and radial glial cells based on analyses of gene markers and CN tumor cells and postulate that CN tumorigenesis is due to dysregulation of radial glial cell differentiation into neurons. Our data demonstrate the potential role of FGFR3 as one of the leading drivers of tumorigenesis in CN.

A rare case of atypical spinal neurocytoma with EGFR mutation in a 12-year-old boy

Spinal neurocytoma (SN), although frequently reportedly as tumors of the central nervous system (CNS), are a distinct class of tumors, which can achieve a better prognosis following subtotal or gross total tumor resection. Nonetheless, even with the premise of successful treatment after tumor resection, poor prognosis after treatment due to the SN high proliferation index (typically known as atypical SN) have been reported. Over the past two decades, atypical SN was only reported in four pediatric cases, amidst the lingering controversy surrounding its postoperative adjuvant therapy. Thus, herein, we report a unique case of atypical SN with epidermal growth factor receptor (EGFR) amplification mutation in a 12-year-old boy. We, however, also highlighted the significance of radiotherapy and target therapy for patients with SN.

Central neurocytoma: SNP array analyses, subtel FISH, and review of the literature

The central neurocytoma (CN) is a rare brain tumor with a frequency of 0.1-0.5% of all brain tumors. According to the World Health Organization classification, it is a benign grade II tumor with good prognosis. However, some CN occur as histologically "atypical" variant, combined with increasing proliferation and poor clinical outcome. Detailed genetic knowledge could be helpful to characterize a potential atypical behavior in CN. Only few publications on genetics of CN exist in the literature. Therefore, we performed cytogenetic analysis of an intraventricular neurocytoma WHO grade II in a 39-year-old male patient by use of genome-wide high-density single nucleotide polymorphism array (SNP array) and subtelomere FISH. Applying these techniques, we could detect known chromosomal aberrations and identified six not previously described chromosomal aberrations, gains of 1p36.33-p36.31, 2q37.1-q37.3, 6q27, 12p13.33-p13.31, 20q13.31-q13.33, and loss of 19p13.3-p12. Our case report contributes to the genetic knowledge about CN and to increased understanding of "typical" and "atypical" variants.

Histology and molecular aspects of central neurocytoma

Central neurocytoma (CN) is a well-differentiated tumor of neural cells occurring within the ventricles. It is composed of monomorphic cells with round, regular nuclei within clear cytoplasm and must be distinguished from other clear cell tumors. Immunohistochemical markers of CN that aid in diagnosis include synaptophysin and neuronal nuclear antigen. The molecular biology of these tumors is becoming increasingly elucidated, particularly with the use of microarray analyses. Several oncogenic pathways have been suggested by these studies. Although progress continues to be made, knowledge of CN has yet to dictate targeted therapies in treating patients with these tumors.

Interphase cytogenetics for 1p19q and t(1;19)(q10;p10) may distinguish prognostically relevant subgroups in extraventricular neurocytoma

Co-deletion of chromosome arms 1p and 19q, characteristic of oligodendroglial tumors, was recently found to be mediated by t(1;19)(q10;p10). To evaluate the prevalence of 1p19q co-deletion and t(1;19) in extraventricular neurocytomas (EVN), we studied tumors from 23 patients, including 13 females and 10 males (median age at diagnosis 34 years, range 2-76 years). Fluorescence in situ hybridization (FISH) studies were performed with probes targeting 1p36/1q25 and 19q13/19p13 to assess for 1p19q co-deletion, as well as chromosome 1 alpha-satellite and 19p12 to detect t(1;19)(q10;p10). FISH was successful in 21 (91%) cases and demonstrated 1p19q co-deletion in five cases (24%) or isolated 1p loss in two cases (10%). Evidence for t(1;19) was found in four (of five) cases with 1p19q co-deletion. Three tumors with 1p19q loss and t(1;19) demonstrated atypical histologic features, compared with one (of 17) tumors without 1p19q co-deletion (P = 0.01, Fisher exact test). In addition, tumors with t(1;19) showed increased mitotic activity compared with tumors without t(1;19) (P = 0.045; Wilcoxon rank sum test). The four patients with t(1;19) developed tumor recurrence (n = 3), or expired (n = 2) 3.5 to 5.5 years after first resection. These results suggest that 1p19q loss and t(1;19) occur in a subset of EVN, and may be associated with aggressive histology in these tumors.

Extraventricular neurocytoma in neurofibromatosis Type 1: case report

Neurocytomas are rare tumors of the central nervous system that are typically located in the ventricular system. The authors report a case of a child with neurofibromatosis Type 1 (NF1) who had a tumor of the optic nerves and chiasm with signal abnormality extending through the diencephalon, as well as an occipital lobe mass, which was presumed to be part of the visual pathway neoplasm. Because the occipital lobe lesion slowly increased in size over time, while the other areas remained stable, a biopsy was performed. Pathological evaluation revealed an extraventricular neurocytoma of extraventricular neurocytoma. To the authors' knowledge, neurocytomas have not been previously reported in patients with NF1. Because visual pathway gliomas are extremely common in children with NF1, they are often treated empirically as low-grade gliomas without histological confirmation. The importance of obtaining a biopsy in lesions that have atypical imaging features is highlighted.

Central neurocytoma: typical magnetic resonance spectroscopy findings and atypical ventricular dissemination

PURPOSE

Central neurocytomas (CNCs) are rare neuronal tumors that have a favorable prognosis and lower rate of recurrence compared with other intraventricular neoplasms. Although it may be difficult to distinguish CNC on conventional neuroimaging, typical MR spectroscopy (MRS) features have been reported. We describe the MRI and MRS features of CNC.

MATERIALS AND METHODS

Eight patients with CNC were reviewed. Three patients underwent presurgical in vivo single-voxel MRS at short echo time (TE, 35 ms) and multi-voxel MR spectroscopic imaging at long TE (144 ms). The surgically resected tumor specimen of one of these patients was also studied ex vivo using high-resolution magic angle spinning (HRMAS) nuclear magnetic resonance.

RESULTS

All eight tumors were located in the lateral ventricles. In six patients, CNC extended into the third ventricle, and in two patients the tumor showed further contiguous intraventricular dissemination into the fourth ventricle. In all three patients who underwent MRS, a characteristic metabolite peak was detected at 3.55 parts per million (ppm) at both long and short TE. HRMAS confirmed the presence of elevated glycine (Gly) at 3.55 ppm, without increase in the concentration of myo-inositol found at the same chemical shift. Elevated choline (at 3.2 ppm) was also seen in all three patients.

CONCLUSION

On MRS, CNCs have a typical appearance with a metabolite peak at 3.55 ppm due to increased Gly, and this feature may be helpful in presurgical diagnosis. Although they are rare benign intraventricular tumors, in atypical cases, CNCs can show extensive intraventricular dissemination into the fourth ventricle.

Recurrent cytogenetic aberrations in central neurocytomas and their biological relevance

Central neurocytomas are rare central nervous system neoplasms. Since the first description, approximately 500 cases of these tumors have been published to date. Nevertheless, only a limited number of genetic studies on these tumors have been reported. Here we investigated 20 "typical" central neurocytomas using array-based comparative genomic hybridization (array-CGH) with the GenoSensor Array 300. The functional significance of detected chromosomal aberrations harboring potent candidate genes was also examined at the mRNA expression level. Each tumor examined displayed DNA copy-number aberrations (CNAs), and mean number of CNAs per tumor was 38.1 +/- 7.1 (range 19-53). Frequent gains were mapped at 2p24.1-22.1, 10q23.3-26.3, 11q23-25, and 18q21.3-qter. Frequent losses were identified at 1pter-36.3, 1p34.3, 6q13-21, 12q23-qter, 17p13.3, 17q11-23, and 20pter-12.3. There were 10 gained and 23 lost single DNA clones affecting >or=40% of samples tested. mRNA expression levels of 24 selected candidate genes harbored in these imbalanced clones were analyzed. MYCN, PTEN, and OR5BF1 were strongly overexpressed, whereas BIN1, SNRPN, and HRAS were found to be strongly underrepresented at the transcriptional level. Thus these data support that MYCN oncogene gain/overexpression accompanied by reduced expression of BIN1 tumor suppressor may contribute to central neurocytoma tumorigenesis.

Central neurocytoma: two case reports and review of the literature

Central neurocytomas are low grade tumours usually located in the lateral ventricles next to Monro foramina. This paper reviews the literature on central neurocytomas observed in the last few years and discusses their clinical, histopathological, immunohistochemical and genetic characteristics. Important correlations between therapeutic strategies and biological findings as well as new genetic discoveries are also discussed. Two illustrative cases in which the authors report preliminary results about molecular analysis of some genetic markers are described.

Neurocytoma: a comprehensive review

Central neurocytomas (CN) are uncommon tumors of the central nervous system, most descriptions of which available in the literature are in the form of isolated case reports and small series. Owing to this rare incidence, diagnosis and management of this neoplasm remain controversial. Usually, these tumors affect lateral ventricles of young adults and display characteristic neuroimaging and histomorphologic findings. Neurocytomas often mimic oligodendrogliomas when confirmation of diagnosis rests on immunohistochemistry, ultrastructure, and genetic studies. Extraventricular neurocytomas, situated entirely within the brain parenchyma and spinal cord, have also been reported. Typically, CN are associated with a favorable outcome although cases with more aggressive clinical course with recurrences are not unknown. MIB-1 labeling index (LI) of >2% often heralds poor prognosis and tumour recurrence. Safe maximal resection is presently considered the ideal therapeutic option, with best long-term prognosis in terms of local control and survival. The role of adjuvant radiotherapy apparently seems to benefit patients with incomplete resection and in atypical neurocytoma. Utility of other therapeutic regimen, however, remains shrouded in controversy. Epidemiology, histogenesis, clinical profile, histology, neuroimaging and therapeutic modalities of neurocytomas have been comprehensively reviewed, with special emphasis on CN and extraventricular neurocytomas and their atypical counterparts.

Atypical extraventricular neurocytoma

Extraventricular neurocytoma (EVN) is a rare brain tumor that poses diagnostic difficulty. Described herein is a case of atypical EVN arising in a 54-year-old woman. A well-circumscribed lesion (3.0 x 3.0 x 3.0 cm) in the right parietal lobe showed diffuse proliferation of monotonous tumor cells with perinuclear clearing within a delicate fibrillary matrix similar to neuropil. Tumor also showed vascular proliferation and high mitotic activity. Immunohistochemically, these tumor cells were strongly positive for synaptophysin both in the neuropil and in the perinuclear cytoplasm, and were negative for glial fibrillary acidic protein and Olig2. Ki-67 labeling index was 13.0% in the most stained areas, but accumulation of p53 was not observed. These findings were compatible with those of EVN with histological atypia. EVN should be considered as a candidate in the differential diagnosis of parenchymal brain tumor, especially oligodendroglioma. The important features are the delicate fibrillary matrix similar to neuropil, diffuse and strong immunoreactivity for synaptophysin, and negative immunoreactivity for Olig2. High proliferative activity without accumulation of p53 suggests that other factors are involved in oncogenesis of atypical EVN.

Molecular cytogenetic analysis in the study of brain tumors: findings and applications

Classic cytogenetics has evolved from black and white to technicolor images of chromosomes as a result of advances in fluorescence in situ hybridization (FISH) techniques, and is now called molecular cytogenetics. Improvements in the quality and diversity of probes suitable for FISH, coupled with advances in computerized image analysis, now permit the genome or tissue of interest to be analyzed in detail on a glass slide. It is evident that the growing list of options for cytogenetic analysis has improved the understanding of chromosomal changes in disease initiation, progression, and response to treatment. The contributions of classic and molecular cytogenetics to the study of brain tumors have provided scientists and clinicians alike with new avenues for investigation. In this review the authors summarize the contributions of molecular cytogenetics to the study of brain tumors, encompassing the findings of classic cytogenetics, interphase- and metaphase-based FISH studies, spectral karyotyping, and metaphase- and array-based comparative genomic hybridization. In addition, this review also details the role of molecular cytogenetic techniques in other aspects of understanding the pathogenesis of brain tumors, including xenograft, cancer stem cell, and telomere length studies.

Central neurocytoma: a review

Central neurocytomas are rare intraventricular neoplasms of the central nervous system, compromising 0.25-0.5% of brain tumors. The diagnosis and management of these tumors remains controversial since most clinical series are small. Typically, patients with central neurocytomas have a favorable prognosis, but in some cases the clinical course is more aggressive. Although histological features of anaplasia do not predict biologic behavior, proliferation markers including MIB-1 might be more useful in predicting relapse. The most important therapeutic modality is surgery, and a safe maximal resection confers the best long-term outcome. In cases of a subtotal resection,'standard external beam radiation can be added or radiation can be delayed until tumor progression occurs. Smaller residual tumor volumes or recurrences can be treated with more conformal radiation or focused radiosurgery. Re-operation for recurrence should be considered if the procedure can be safely performed. Chemotherapy may be useful for recurrent central neurocytomas that cannot be resected and have been radiated, although long-term responses have not been reported for chemotherapy. Overall, this paper reviews the findings of the larger studies and highlights some of the important case reports that contribute to the current management of central neurocytomas.

Epidemiology and pathology of intraventricular tumors

Tumors that primarily or exclusively involve the ventricular system constitute a rare and heterogeneous group. Certain histologic tumor types predominantly occur in children, whereas others are more common in adults. Tumor location provides additional clues to correct diagnosis. When used in conjunction with clinical and radiologic data, histopathologic features can distinguish among this wide range of possibilities to provide the correct diagnosis for optimal patient management.

Genetic differences between neurocytoma and dysembryoplastic neuroepithelial tumor and oligodendroglial tumors

OBJECT

Because of their histological similarities, it is occasionally difficult to differentiate neurocytoma and dysembryoplastic neuroepithelial tumor (DNT) from oligodendroglial tumors. This study was conducted to investigate genetic differences among these tumor types in terms of loss of heterozygosity on chromosomes 1p and 19q, and p53 gene mutation.

METHODS

A total of 24 tumors were analyzed, consisting of eight central neurocytomas, three DNTs, seven oligodendrogliomas, four oligoastrocytomas, and two undetermined extraventricular tumors with neurocytoma features (ETNFs). Allelic loss was determined using microsatellite markers that cover the common deletions on chromosomes 1p and 19q in oligodendrogliomas. A p53 gene mutation was identified using polymerase chain reaction-single-strand conformation polymorphism analysis and subsequent direct sequencing. Immunohistochemical studies with synaptophysin and electron microscopy investigations were also conducted. Allelic loss on 1p and 19q was detected in six oligodendrogliomas (86%) and in three oligoastrocytomas (75%), but in none of the central neurocytomas or DNTs. A p53 missense mutation was detected at codon 161 (GCC-->ACC, Ala-->Thr) in only one oligoastrocytoma without allelic loss. Synaptophysin was expressed in all central neurocytomas and DNTs, in three oligodendrogliomas (43%), and in three oligoastrocytomas (75%). Of the ETNFs, one demonstrated synaptophysin expression and neural ultrastructures but lacked genetic alterations, whereas the other showed allelic loss on 1p and 19q but was negative immunohistochemically and ultrastructurally. The former was diagnosed as a potential intraparenchymal neurocytoma and the latter as an oligodendroglioma.

CONCLUSIONS

Despite histological similarities, central neurocytomas and DNTs are genetically distinct from oligodendroglial tumors. Examination for allelic loss on 1p and 19q and for p53 mutation can be useful for making this distinction.

Central neurocytoma: long-term follow-up of a paediatric case

In order to gain a better understanding of the clinical and histological features of central neurocytoma and the role of radiotherapy in the treatment of these tumours, we present an unusual paediatric case and review the pertinent literature. Most patients present in the second and third decade of life, rarely in the teenage years and exceptionally in children. Our patient was treated by a combined surgical and radiation therapy treatment for a central neurocytoma at the age of 7 years, but the tumour had been diagnosed when she was 3 years old. At a 38-year follow-up, she is well with no evidence of tumour progression. This patient seems to be the youngest histologically proven case of central neurocytoma and with the longest recorded survival.

Central neurocytomas are genetically distinct from oligodendrogliomas and neuroblastomas

AIMS

Central neurocytoma is a rare central nervous system tumour typically found in the lateral ventricles and at the septum pellucidum. Histologically, it resembles oligodendrogliomas and yet ultrastructurally, it shows neuronal differentiation. Its molecular oncogenesis is not known. The aim of this study was to examine whether major genetic events found in oligodendrogliomas and neuronal tumours, namely allelic deletions of chromosomes 1p and 19q and N-myc amplification, can be found in central neurocytomas. As there was one report describing gain of chromosome 7 in central neurocytomas, we also examined epidermal growth factor receptor (EGFR) amplification, as the EGFR gene is located at chromosome 7p.

METHODS AND RESULTS

Nine central neurocytomas and matched blood samples were examined for loss of heterozygosity (LOH) of 1p and 19q13.2-13.4 with 23 finely mapped microsatellite markers. N-myc amplification was studied by fluorescence in-situ hybridization using paraffin-embedded sections. EGFR amplification was tested for by differential PCR. Six of nine (67%) tumours showed LOH at one or more loci at 1p and 5/9 (56%) of cases showed LOH at 19q. However, common regions of deletion cannot be identified. The majority of informative markers are retained at 1p (84%) and 19q (86%). Only one tumour showed amplification of N-myc and none of the cases showed amplification of EGFR.

CONCLUSION

Central neurocytomas are genetically distinct from oligodendrogliomas, and chromosomes 1p and 19q probably do not play an important role in their pathogenesis. N-myc and EGFR amplification are rare.

Detection of chromosomal imbalances in central neurocytomas by using comparative genomic hybridization

OBJECT

Central neurocytomas are rare neuronal tumors commonly found in the intraventricular regions. Little is known about the tumorigenesis of these neoplasms. The aim of this study was to provide an overview of genetic imbalances in central neurocytomas.

METHODS

In this study, comparative genomic hybridization was used to identify DNA sequence copy number changes (losses and gains) in a series of 10 central neurocytomas. Tumor DNA and normal reference DNA were differentially labeled and allowed to cohybridize to normal metaphase chromosomes. After hybridization and fluorescent staining of the bound DNA, regions of gain or of loss of DNA sequences were detected as changes in the tumor/normal fluorescence intensity ratio along the target metaphase chromosomes. A gain of DNA sequence was detected in chromosomes 2p, 10q, and 18q. A protooncogene, Bcl2, which maps to 18q21, was evaluated by immunohistochemical analysis to determine its role in the formation of central neurocytomas.

CONCLUSIONS

In this study the authors identified recurrent genetic changes on chromosomes 2p, 10q, and 18q in central neurocytomas and highlighted chromosomal regions for additional mapping and cloning of candidate genes that are important in the development of central neurocytomas.

So-called malignant and extra-ventricular neurocytomas: reality or wrong diagnosis? A critical review about two overdiagnosed cases

Central neurocytoma (CN) is described as a rare intra-ventricular benign neuronal tumor of the brain. Two primary tumors first diagnosed as malignant and extra-ventricular neurocytomas are reported here. Histologically, the tumor of the first patient, a forty-one-year-old man, consisted of monotonous cells with round nuclei, but no fibrillar background. The second tumor, in a nineteen-year-old girl, showed areas of moderately pleomorphic round cells, with numerous rosettes and ganglion cell differentiation, in an abundant fibrillary network. Both presented calcifications. Mitoses were more frequent in recurrences and spinal locations than in the primaries. All tumors stained strongly for synaptophysin, and GFAP was partly positive in the first case only. Patients received post-surgical radiotherapy and were still alive eight and six years, respectively, after initial surgery. The interpretation of atypical cases, such as ours is not easy: the diagnoses finally retained were oligodendroglioma in the first case and ganglioneuroblastoma in the second case. Furthermore, neurocytomas atypical either by their unusual topographical or histological presentation or by their poor prognosis, have been frequently entitled in this way on synaptophysin positivity. So, we were prompted to reassess the entity of CN, seventeen years after the first description, to re-appreciate the reality of anatomo-clinical variants and to discuss the value of synaptophysin positivity in these tumors. In conclusion, it seems preferable to individualize true classical CN, which has a favorable outcome, from so-called extra-ventricular, atypical and anaplastic, clinically malignant neurocytomas for which complementary treatment is required.

Central neurocytoma: morphological, flow cytometric, polymerase chain reaction, fluorescence in situ hybridization, and karyotypic analyses. Case report

The results of cytogenetic and molecular genetic analysis of a central neurocytoma are presented. Central neurocytomas are intriguing neoplasms that exhibit primarily neuronal, but also glial characteristics, which indicate an origin from a pluripotential neuroglial precursor. The authors describe an intraventricular neurocytoma in an 11-year-old boy that showed anaplastic features with widespread necrosis and mitoses, as well as extensive calcification and foci that exhibited marked neuronal differentiation with clusters of ganglion cells. Immunohistochemical examination showed prominent synaptophysin and neurofilament positivity and focal glial fibrillary acidic protein positivity. Electron microscopy revealed abundant neuritic processes with microtubules and dense core granules as well as mature ganglion cells. Flow cytometry studies revealed increased S (7.8%) and G2M (9.7%) phase components. Molecular and cytogenetic studies were undertaken to assess whether there were similarities to two other tumor types that exhibit neuronal differentiation, the neuroblastoma and medulloblastoma. Polymerase chain reaction and fluorescence in situ hybridization (FISH) analysis revealed no evidence of amplification of the MYCN oncogene or chromosome 1p deletion, which are common in neuroblastomas. Chromosomal analysis by G banding revealed a complex karyotype, with counts in the near-diploidy range (45-48). Two chromosomes 1 appeared normal on G banding and FISH analysis, with p58 signals present on the distal p arm of both chromosomes 1; however, three additional copies of distal 1q were present in rearrangements with 4 and 7. Although the histological findings indicate a kinship to the neuroblastoma and medulloblastoma, the central neurocytoma appears to have a different karyotypic profile, although more cases need to be assessed using molecular genetic analysis.