Anaplastic ependymomas: clinical features and tumour suppressor gene p53 analysis

Sudden Unexpected Death in a Child From an Anaplastic Ependymoma

Primary central nervous system tumors are an extremely rare cause of sudden, unexpected death in children as most patients develop symptoms because of increased intracranial pressure and seek medical attention. Rarely, a forensic pathologist may encounter a primary intracranial neoplasm in a pediatric decedent that was not suspected before death. Herein, we present a case of a supratentorial neuroepithelial tumor found at autopsy in a 3-year-old African American boy without any reported significant medical history. The tumor had significant mass effect and caused cerebral edema, which ultimately resulted in transtentorial herniation and death. The gross, histopathological, immunohistochemical, and ultrastructural findings were most consistent with an anaplastic ependymoma.

Prognostic value of Ki-67 (MIB-1) and p53 in ependymomas

To determine whether Ki-67 (MIB-1) and p53 have prognostic value in ependymomas, clinicopathologic study was undertaken in 29 patients with this tumor. The clinical course correlated well with the histological grade according to the World Health Organization (WHO) grading system, and it was the worst in patients with anaplastic ependymoma. The percent expression of MIB-1 and p53 correlated with the histological grade of malignancy. With regard to the subtypes of benign ependymoma, the clinical course was the worst in clear-cell ependymoma, which had a significantly higher expression of MIB-1 and p53 than the other subtypes. Tanycytic ependymoma showed the most benign clinical course and the lowest expression of MIB-1 and p53. Although the WHO grading generally tended to correlate with the clinical course of ependymomas, these two subtypes--clear-cell ependymoma and tanycytic ependymoma--exhibited biological properties different from those of other grade II ependymomas.

Giant cell ependymoma: a case report

Ependymomas account for 3-9% of all neuroepithelial tumors. A peculiar variant of ependymoma known as "giant cell ependymoma" ("GCE") is especially rarely reported, it may pose some difficulties for the diagnosing neuropathologist. Here we present a case of a giant cell ependymoma occuring in a 17-year-old patient with the history of 2-year recurrent headaches and a 1-month history of vision impairment. CT scanning demonstrated a mass in the left occipital lobe, arising from the occipital horn of the lateral ventricle. Histological, immunohistochemical and electron microscopic findings were consistent with high-grade ependymoma. Especially striking was the presence of bizzare pleomorphic giant cells which predominated in the tumor tissue. As a result the diagnosis of GCE was established. This type of neoplasm necessitates, at least in theory, differentiation with anaplastic oligodendroglioma, clear cell ependymoma, pleomorphic xanthoastrocytoma, giant cell glioblastoma, and subependymal giant cell astrocytoma. To date giant cell ependymomas (GCEs) were reported in seven cases in the literature. To the best of our knowledge this is the 8th case in the literature. In spite of apparently "worrisome" histology GCE seems to be a neoplasm with a relatively good prognosis.

Infratentorial giant cell ependymoma: a rare variant of ependymoma

We describe a giant cell ependymoma occurring in a 50-year-old man. The mass was located in the posterior aspect of the foramen magnum, extending from the cerebellar tonsil to the upper cervical spine. The tumor was a highly cellular neoplasm showing biphasic histology. Diffuse sheets of non-cohesive atypical giant cells, having eccentrically located single or multiple nuclei and plump eosinophilic cytoplasm, partly infiltrated the desmoplastic inflammatory stroma. Parts of perivascular pseudorosette-forming or pseudopapillary areas were composed of atypically elongated cells, which looked like conventional anaplastic ependymoma. There was a transitional area between two patterns. Numerous mitoses and focal necrosis were observed. Immunohistochemically, the tumor cells were immunoreactive for glial fibrillary acidic protein, vimentin, S-100 protein, and CD99. None of the tumor cells showed immunoreactivity for epithelial membrane antigen except for the intracytoplasmic lumen of a few vacuolated cells. Ultrastructurally, tumor cells were ependymal in nature; we noted cytoplasmic intermediate filaments and intercellular microrosettes with microvilli, cilia, and long zonula adherens. The features of this tumor, e.g. its superficial location, mixed giant cells, perivascular pseudorosettes or papillaries, complicated its differentiation from rhabdoid/papillary meningioma. However, immunohistochemistry and electron microscopy confirmed the diagnosis of ependymoma. The giant cell variant should be included in the subclassification of the ependymoma.

The expression of p73, p21 and MDM2 proteins in gliomas

p73 protein, a member of the p53 family protein, induce p21 and MDM2 transcription. In some carcinomas, the expression of p73 was higher in carcinoma than in normal tissue, and the overexpression was correlated to grade, stage or prognosis. However, either the expression of p73 protein or the relationship among p73, p21 and MDM2 proteins was not known well in glioma. In this study, we examined the expression of p73, p21 and MDM2 proteins immunohistochemically and analyzed the relationship among these three proteins in sixty surgical specimens of gliomas including 10 glioblastomas, 10 anaplastic astrocytomas, 6 diffuse astrocytomas, 8 pilocytic astrocytomas, 1 anaplastic ependymoma, 8 ependymomas, 9 anaplastic oligodendroglial tumors and 8 low grade oligodendroglial tumors. The p73 labelling index (LI)s and p21 LIs differed among the tumor types, but there was no difference in the MDM2 LIs among all of the tumor types. The mean p73 LI of ependymomas was significantly higher than in any other tumor type. The mean p2I LIs of ependymomas and pilocytic astrocytomas were significantly higher than in any other tumor type. There were no significant correlations among p73 LIs, p21 LIs, MDM2 LIs and MIB-1 LIs in all p73 immunopositive tumors. The present results suggest that p73 and p21 overexpression of ependymomas and p21 overexpression of pilocytic astrocytomas are one of the features of these tumors, and that p73 overexpression does not influence the expression manners of either p21 or MDM2 in gliomas.

Molecular evidence of apoptotic death in malignant brain tumors including glioblastoma multiforme: upregulation of calpain and caspase-3

Cell death in the core of human brain tumors is triggered by hypoxia and lack of nutrients, but the mode of cell death whether necrosis or apoptosis is not clearly defined. To identify the role of apoptosis in brain tumor cell death, we investigated macromolecular (RNA and protein) synthesis and activity in the central to peripheral region of benign [desmoplastic infantile ganglioglioma (DIG) and transitional meningioma (TMG)] and malignant [ependymoma (END), anaplastic astrocytoma (APA), and glioblastoma multiforme (GBM)] brain tumors derived from five patients who had not received previously radiotherapy or chemotherapy. Normal brain tissue (NBT) served as control. RT-PCR analysis of tumor tissues covering central to peripheral regions detected mRNA overexpression of pro-apoptotic gene bax in malignant tumors, indicating a commitment to apoptosis. The mRNA expression of calpain (a Ca(2+)-dependent cysteine protease) and calpastatin (endogenous calpain inhibitor) was altered resulting in an elevated calpain/calpastatin ratio. Calpain content and activity were increased, suggesting a role for calpain in cell death. In the mitochondria-dependent death pathway, caspase-9 and caspase-3 were also overexpressed in tumors. The increased caspase-3 activity cleaved poly(ADP-ribose) polymerase (PARP). Agarose gel electrophoresis detected a mixture of random and internucleosomal DNA fragmentation in malignant brain tumors. Overexpression of pro-apoptotic bax, upregulation of calpain and caspase-3, and occurrence of internucleosomal DNA fragmentation are now presented indicating that one mechanism of cell death in malignant brain tumors is apoptosis, and that enhancement of this process therapeutically may promote decreased tumor growth.

Immunohistochemical markers for prognosis of ependymal neoplasms

Intracranial ependymomas are the third most common primary brain tumor in children. Although clinical and histological criteria for ependymoma prognosis are recognized, studies have reported contradictory results. Prognostic significance based on immunohistochemistry of ependymomas has been reported in a few studies. One-hundred and twelve patients with intracranial ependymomas were examined retrospectively for immunoexpression of various tumor-associated antigens and apoptosis. The results demonstrated significant preponderance of expression of the tenascin, vascular endothelial growth factor protein (VEGF), epidermal growth factor (EGFR) and p53 protein in high-grade tumors. Also high-grade ependymomas revealed more prominent labeling indices (LI) for proliferative marker Ki-S1 and apoptotic index (AI), and lower LI for cyclin-dependent kinase inhibitors p27/Kipl and pl4ARF. For low-grade ependymomas the progression-free survival time (PFS) was found to be significantly shorter for Ki-S1 LI > 5%, and for tenascin, VEGF and EGFR positivity. For high-grade ependymomas PFS was found to be significantly reduced for p27 LI < 20%, p14ARF LI < 10%, for p53 positivity, and for AI < 1%. The CART modeling process exhibited five final groups of ependymoma patients (1) low-grade and tenascin-negative; (2) low-grade and tenascin-positive; (3) high-grade and p53-negative with p14 LI > 0%; (4) high-grade with combination of either p53 positivity and p14 LI > 10% or p53 negativity and p14 LI < 10%; (5) high-grade and p53-positive with pl4 LI < 10%. In summary, some immunohistochemical variables were found to be the strong predictors of ependymoma recurrence and they seem to be useful for assessing individual tumor prognosis in routinely processed biopsy specimens together with tumor grade. For histologically benign ependymomas immunohistochemical study should be focused on Ki-S1, tenascin, EGFR and VEGF evaluation, whereas p53 expression and number of p27, p14 and ISEL-positive nuclei will be of value in determining PFS from high-grade ependymomas.

Genetics of nervous system tumors

Genetic aberrations are being defined for the various glial tumors. Astrocytic tumors can evolve by two different pathways. The genetic aberrations now being defined for these two pathways are different and can be associated with the grade of malignancy. In oligodendrogliomas, the genetic lesions differ from the astrocytic tumors, and several markers have been linked to chemosensitivity response and survival. Genetic aberrations in ependymomas also differ from the astrocytic tumors or oligodendrogliomas. Although additional cases are needed to study the genetic aberrations, the abnormalities identified suggest that spinal cord tumors carry different markers than intracranial tumors and that the markers within the cranium may be different based on their location.

Gain of 1q and loss of 22 are the most common changes detected by comparative genomic hybridisation in paediatric ependymoma

Ependymomas are the third most common brain tumour in the paediatric population. Although cytogenetic and molecular analyses have pinpointed deletions of chromosomes 6q, 17, and 22 in a subset of tumours, definitive patterns of genetic aberrations have not been determined. In the present study, we analysed 40 ependymomas from paediatric patients for genomic loss or gain using comparative genomic hybridisation (CGH). Eighteen of the tumours (45%) had no detectable regions of imbalance. In the remaining cases, the most common copy number aberrations were loss of 22 (25% of tumours) and gain of 1q (20%). Three regions of high copy number amplification were noted at 1q24-31 (three cases), 8q21-23 (two cases), and 9p (one case). Although there was no association with the loss or gain of any chromosome arm or with benign versus anaplastic histologic characteristics, the incidence of gain of 7q and 9p and loss of 17 and 22 was significantly higher in recurrent versus primary tumours. This study has identified a number of chromosomal regions that may contain candidate genes involved in the development of different subgroups of ependymoma.

CDKN2A/p16 in ependymomas

Sixteen cases of ependymoma were studied for CDKN2A/p16 inactivation by immunohistochemistry using a p16 monoclonal antibody, by homozygous deletion (HD) assay and 5'CpG promoter methylation assay (methylation-specific PCR). Three out of 16 cases were p16 immuno-negative: two corresponded to grade II ependymomas and one to grade III. The latter ependymoma, characterized by a high Ki-67/MIB-1 LI, was the only one of the whole series to show CDKN2A HD. No promoter methylation was found in the two immuno-negative cases without CDKN2A HD. Alternative mechanisms, such as point mutations or alterations in p16 post-translational regulation, may be responsible for p16 inactivation. Since in our series just one out of eight anaplastic cases showed negative immunostaining and CDKN2A HD, p16/CDKN2A inactivation may not play an important role in the malignant transformation of ependymomas. Amplification of CCNDI and CDK4, p27/Kipl degradation and TP53 mutations were previously studied by other authors and were demonstrated not to correlate with anaplasia. Up to date, molecular genetic studies have not been useful in recognizing the anaplastic variant in ependymomas.

Recurrence of Infantile Supratentorial Ependymoma after 23-Year Remission following Surgical Removal and Radiation Therapy

We report on a patient with ependymoma who had a recurrence after long-term remission. The patient developed frontoparietal ependymoma at the age of one year and ten months. The tumor was radically removed and postoperative radiation therapy was performed. A calcified area adjacent to the area of surgical removal remained unchanged until the patient was 18 years old. The patient was healthy except for mild hemiparesis until an MRI scan performed when he was 25 years old showed regrowth of the tumor. The patient underwent surgery with additional radiation therapy and was discharged. The 23-year interval until tumor recurrence in this case is far beyond the so-called risk period of “Collins’ law”. Immunohistochemical study with MIB-1 and anti-p53 antibody showed a high proliferative potential of the primary and recurrent tumors and possible p53 mutation in the primary tumor. This is the first report to describe the detailed clinical course and histological features of a recurrent infantile ependymoma that progressed after Collins’ risk period. It seems that follow-up of ependymoma patients after initial treatment should be performed regularly for a longer period in cases showing radiological evidence of a residual lesion.

Genetics of brain tumors

Brain tumors are among the most common forms of cancer in children and account for most cancer-related deaths in this age group. The incidence of brain tumors appears to be increasing in children, while therapeutic advances have been modest. Few genetic studies exist on pediatric brain tumors, in part because tissue from low-grade and brain stem tumors is not readily available, and also because individual centers have relatively few cases. Genetic changes in infiltrating astrocytomas involve genes in the p53 and RB pathways, and show alterations that are similar to infiltrating astrocytomas in adults. The PTC gene is mutated in a subgroup of medulloblastomas, and may lead to increased proliferation in granule cells that normally express this receptor. Further studies are needed to identify genetic alterations in pilocytic and low-grade astrocytomas, which account for 40% of brain tumors in children.

Amplification and overexpression of mdm2 gene in ependymomas

Ependymomas rarely show p53 gene alteration, and the tumorigenic mechanism of ependymomas still remains to be elucidated. We investigated the amplification and overexpression of mdm2 gene, whose product (MDM2) is considered to be one of the major cellular regulators of p53-mediated growth control, in 26 specimens of ependymomas obtained from 20 patients. The majority of the ependymomatous samples (96%) showed at least focal immunopositivity for MDM2; however, only 8% of the samples were immunopositive for p53. mdm2 gene amplification was detected in 35% of the samples by differential polymerase chain reaction, all of which overexpressed MDM2. These results suggest that the amplification and/or overexpression of mdm2 may be one of the major molecular events occurring in the tumorigenesis of ependymomas.

Molecular genetic analysis of non-astrocytic gliomas

AIMS

Oligodendroglial tumours follow genetic pathways different from but overlapping with those of astrocytic tumours. The aim of this study was to examine whether major genetic events such as loss of chromosome 10 and p53 mutation found in astrocytic gliomas are also involved in the development and anaplastic transformation of non-astrocytic gliomas and to correlate the findings with histopathological subtypes of these tumours.

METHODS AND RESULTS

Sixty-one formalin-fixed, paraffin-embedded oligodendroglial and ependymal tumours (16 oligodendrogliomas, 12 anaplastic oligodendrogliomas, seven oligoastrocytomas, 24 ependymomas and two anaplastic ependymomas) were examined for allelic deletions on chromosome 10q23 and 10q25-26 regions, mutations of PTEN/MMAC1 and p53, MDM2 gene amplification and apoptosis. The frequencies of allelic deletions at marker D10S2491 (which mapped within PTEN/MMAC1) and between markers D10S209 and D10S587 (where DMBT1 was located) were found to be < 30% in both types of non-astrocytic gliomas. High frequency of allelic deletions was detected at marker D10S215 (80%) at the proximal 10q23 region in both oligodendroglial and ependymal tumours and between markers D10S216 (42%) and D10S169 (67%) at distal 10q25-26 region in oligodendroglial tumours. No mutations of PTEN/MMAC1 were found. p53 mutations were detected in three oligoastrocytomas and one ependymoma; three out of five mutations were found in exon 4. MDM2 gene amplification was found in one ependymoma harbouring wild-type p53. The apoptotic index was lower in p53-mutated tumours than in tumours with wild-type p53.

CONCLUSION

The telomeric end of chromosome 10q could be involved in the development and anaplastic transformation of oligodendroglial tumours. Mutations of PTEN/MMAC1 and p53, amplification of the MDM2 gene and allelic loss on chromosome 10q do not play a major part in the pathogenesis or anaplastic transformation of oligodendrogliomas and ependymal tumours.

p73 gene transcripts in human brain tumors: overexpression and altered splicing in ependymomas

The p73 gene encodes a protein that shares structural and functional homologies with the p53 tumor suppressor protein. The p73 gene is monoallelically expressed in normal tissue, maps to chromosome 1p36 and is deleted in human neuroblastoma cell lines. Alternative splicing of exon 13 in p73 transcripts generates two isoforms, p73alpha and p73beta, that differ in their carboxy-terminus and in their ability to form homotypic interactions. In this study, we investigated, in 129 human central nervous system tumors of various histological types, the levels of p73 transcripts and the splicing characteristics of p73 mRNA. Whereas p73 mRNA content was consistently low in most tumoral types, especially in meningiomas, some glioblastomas, medulloblastomas and metastases exhibited elevated p73 mRNA content. However, ependymomas expressed consistently high amounts of p73 mRNA, significantly different from the other tumoral types. Whereas the short (p73beta) isoform accounted for 20-25% of the total p73 mRNA in most of the tumors, these splicing characteristics were altered in ependymomas (only 9% of p73beta) and in neurinomas (up to 53% of p73beta). These observations suggest tissular or tumoral differences in the control of p73 gene transcription and alternative splicing, and raise the problem of the role of p73 isoforms in the control of tumor growth, particularly in ependymomas.

Intracranial ependymomas: a review

Ependymomas are rare neuroectodermal tumors arising from ependymal cells of the ventricular system, choroid plexus, filum terminale, and central canal of the spinal cord (1,2). This review focuses on intracranial ependymomas with special emphasis on pathology, etiology, cytogenetic characteristics, and adjuvant radiation therapy. Recent advances in neurosurgical technique, radiation therapy, and molecular biology have affected management of these tumors and have the potential to increase long-term cure rates. The role of highly advanced radiation therapy techniques such as stereotactic radiosurgery will need to be better defined.

Multiple radiation-induced intracranial lesions after treatment for pituitary adenoma. Case report

This 53-year-old man presented with a syncopal episode 31 years after undergoing craniotomy and external-beam radiation for a pituitary macroadenoma. A gadolinium-enhanced magnetic resonance (MR) image of the brain demonstrated a 2.5-cm enhancing mass in the right caudate region that had not been seen on previous studies. A stereotactically guided biopsy procedure was performed to obtain specimens from the mass, which were consistent with ependymoma. The MR image also revealed two additional lesions that appeared to be within the radiation fields: a right temporal meningioma and a left frontal cavernous malformation. A review of the literature found three previous reports in which ependymomas presented after radiation therapy.

The molecular biology of ependymomas

Intracranial ependymomas are the third most common primary brain tumor in the pediatric population. Although an anaplastic variant is recognized, numerous studies examining the prognostic implications of histological features, such as necrosis, endothelial proliferation and mitoses, have yielded contradictory results. In order to improve outcome prediction in affected patients and to refine therapeutic decision-making, there is a strong need for identifying relevant biological correlates of tumor behavior. The molecular biology of tumors is a rapidly expanding field and includes investigations into cytogenetics, oncogenes, growth factors, growth factor receptors, hormonal receptors, proliferation markers, apoptosis, cell cycle genes and cell adhesion molecules, as well as factors potentially related to therapeutic resistance, such as the multidrug resistance gene. The molecular biology of astrocytic tumors in adults has been the subject of many studies; however, relatively few studies have been focused on ependymomas. Herein we review potential oncological markers in ependymomas that have been identified to date and highlight the limitations of our current knowledge as a basis for defining areas for future investigation.