Clonal telomeric fusions and chromosome instability in a subcutaneous sacrococcygeal myxopapillary ependymoma

Pediatric Extraspinal Sacrococcygeal Ependymoma: Report of Two Cases and Literature Review

Primary central nervous system (CNS) tumors represent the most common solid tumors in childhood. Ependymomas arise from ependymal cells lining the wall of ventricles or central canal of spinal cord and their occurrence outside the CNS is extremely rare, published in the literature as case reports or small case series. We present two cases of extra-CNS myxopapillary ependymomas treated at our institution in the past three years; both cases originate in the sacrococcygeal region and were initially misdiagnosed as epidermoid cyst and germ cell tumor, respectively. The first case, which arose in a 9-year-old girl, was treated with a surgical excision in two stages, due to the non-radical manner of the first operation; no recurrence was observed after two years of follow-up. The other case was a 12-year-old boy who was treated with a complete resection and showed no evidence of recurrence at one-year follow-up. In this paper, we report our experience in treating an extremely rare disease that lacks a standardized approach to diagnosis, treatment and follow-up; in addition, we perform a literature review of the past 35 years.

Surgical management of a rare myxopapillary ependymoma of the gluteal region: A case report

Background:

Ependymomas are rare tumors originating from neuroepithelial cells lining the wall of the ventricles or central canal of the spinal cord. While these tumors mainly occur within the central nervous system (CNS), there are occasional reports in children and young adult patients with a primary tumor occurrence outside of the CNS. Ependymomas of the sacrococcygeal region have been infrequently described in the literature with no standard of care established. We present a case report and review of the literature regarding this rare entity.

Case Description:

A 24-year-old woman presented with right gluteal pain worsened by sitting and a palpable soft tissue mass of the sacrococcygeal region. Magnetic resonance imaging revealed a 3.7 cm cystic mass centered in the right gluteal region. She underwent a biopsy at an outside institution, with histology revealing myxopapillary ependymoma. The patient was referred to our hospital and underwent an interdisciplinary neurosurgical and orthopedic oncology en bloc resection of the ependymoma, which intraoperatively appeared to originate from the coccygeal nerve.

Conclusion:

In the present report, the authors demonstrate that a myxopapillary ependymoma may present as an isolated gluteal mass attached to the coccygeal nerve, without frank CNS involvement. Furthermore, an interdisciplinary approach to surgical resection of this lesion appears to represent an effective treatment modality.

Neurogenic tumors of soft tissue

Neurogenic tumors are an uncommon yet important category of soft tissue tumors in children and adolescents because of their frequent association with various genetic syndromes. The heterogeneous cellular composition of the peripheral nerve and the wide metaplastic capacity of the neural crest and its derivatives generate a variety of neoplasms with neurogenic differentiation. This article reviews the clinicopathologic features and differential diagnosis of neurogenic tumors in the first two decades of life, and highlights use of selected ancillary methods for diagnosis.

Biological background of pediatric medulloblastoma and ependymoma: a review from a translational research perspective

Survival rates of pediatric brain tumor patients have significantly improved over the years due to developments in diagnostic techniques, neurosurgery, chemotherapy, radiotherapy, and supportive care. However, brain tumors are still an important cause of cancer-related deaths in children. Prognosis is still highly dependent on clinical characteristics, such as the age of the patient, tumor type, stage, and localization, but increased knowledge about the genetic and biological features of these tumors is being obtained and might be useful to further improve outcome for these patients. It has become clear that the deregulation of signaling pathways essential in brain development, for example, sonic hedgehog (SHH), Wnt, and Notch pathways, plays an important role in pathogenesis and biological behavior, especially for medulloblastomas. More recently, data have become available about the cells of origin of brain tumors and the possible existence of brain tumor stem cells. Newly developed array-based techniques for studying gene expression, protein expression, copy number aberrations, and epigenetic events have led to the identification of other potentially important biological abnormalities in pediatric medulloblastomas and ependymomas.

Myxopapillary Ependymoma and Fatty Filum in an Adult with Tethered Cord Syndrome: A Shared Embryological Lesion? Case Report

OBJECTIVE AND IMPORTANCE:

Myxopapillary ependymoma and fatty fila are traditionally thought to arise via completely different pathophysiologies. Recognition of these distinct pathologies in the same patient is important for appropriate treatment and prognosis.

CLINICAL PRESENTATION:

A 28-year-old woman presented with low back pain, bilateral leg radiculopathies, and mild leg weakness suggestive of tethered cord syndrome. Magnetic resonance imaging revealed lesions in the area of the conus medullaris consistent with a myxopapillary ependymoma and fatty filum.

INTERVENTION:

Under the surveillance of intraoperative electromyographic monitoring, the patient underwent an L4–S2 laminectomy for transection of the fatty filum and gross total resection of the mass. Histopathological examination confirmed the presence of these two distinct pathologies.

CONCLUSION:

We report an unusual case of a myxopapillary ependymoma coexisting with a fatty filum in an adult patient. To the best of our knowledge, this association has not yet been reported. This raises the interesting question of a possible associative or causative relationship between these distinct pathologies, which have traditionally been thought to arise from different mechanisms.

Structural genomic abnormalities of chromosomes 9 and 18 in myxopapillary ependymomas

Myxopapillary ependymomas (MPEs) are low-grade neuroepithelial tumors typically occurring in the conus-cauda equina-filum terminale region. Limited molecular and cytogenetic analysis of MPEs has not demonstrated consistent abnormalities. In an attempt to clarify the chromosomal status of these tumors and identify commonly aberrant regions in the genome we have combined 3 molecular/cyto/genetic methods to study 17 MPEs. Comparative genomic hybridization of 7/17 tumors identified concurrent gain on chromosomes 9 and 18 as the most frequent finding. The majority of the 17 tumors were also studied using microsatellite analysis with marker spanning the whole chromosomes 9 and 18 and interphase-FISH with centromeric probes for both chromosomes. Our combined results were consistent with concurrent gain in both chromosomes 9 and 18 in 11/17 cases, gain of either chromosome 9 or 18 and imbalance in the other chromosome in 3/17 tumors and allelic imbalances of chromosomes 9 or 18 in 3/17 and 1/17 tumors, respectively. Other abnormalities observed included gain of chromosomes 3, 4, 7, 8, 11, 13, 17q, 20, and X and loss of chromosomes 10 and 22. Our findings represent some steps towards understanding the molecular mechanisms involved in the development of MPE.

Subcutaneous myxopapillary ependymoma presenting as a childhood sacrococcygeal tumor: a case report

Subcutaneous myxopapillary ependymoma in a sacrococcygeal location is an uncommon lesion. We report such a case in a 16-mo-old female child, who presented with a sacrococcygeal mass since birth. The cytological picture was that of a malignant small round cell tumor and the diagnosis was missed on cytology, which was retrospectively confirmed on comparison with histology. Although rare, this lesion can be a potential diagnostic pitfall and needs to be distinguished from other malignant tumors occurring at this age and at a similar location, like sacrococcygeal teratoma with immature elements, primitive neuroectodermal tumor (PNET), and PNET with ependymal differentiation.

Complex cytogenetic abnormalities including telomeric associations and MEN1 mutation in a pediatric ependymoma

Ependymomas are neuroectodermal tumors of the brain and spinal cord. Some recurrent cytogenetic aberrations have been reported in these tumors, including alterations involving chromosomes 22, 6, and 11. However, consistent molecular alterations have not been identified in ependymal tumors. We studied a recurrent ependymoma in a 3-year-old patient by standard cytogenetic and molecular analysis of TP53 and MEN1 genes. In the present case, we found many of the cytogenetic features previously described as being recurrent in ependymomas, including unstable telomeric alterations. Furthermore, we detected a novel acquired heterozygous mutation in the MEN1 gene. The chromosomal instability produced by the telomeric alterations and the mutation in the MEN1 gene could be important events in the tumorigenesis of ependymomas.

Telomeric associations in cigarette smokers exposed to low levels of X-rays

Telomeric association (TA), i.e. fusion of chromosomes by their telomeres, predisposes a cell to genetic instability. Because of this we investigated the effect of X-rays exposure and cigarette smoking on the frequency of TA in peripheral blood lymphocytes of exposed individuals, in order to determine if TA can be a chromosomal marker in populations exposed to these carcinogens and if there is an synergistic effect between both agents. We found that the exposed groups show a greater percentage of TA when compared with the control group (P<0.001). However, although the percentage of metaphases with TA in the group with combined exposure (12.6%) was greater than in the others exposed groups (P<0.05), this value was less than the sum of the two individual effects (15.1%). Our results suggest that probably there is not an additive or synergistic effect between X-rays and smoking, and that TA may be a useful cytogenetic marker for evaluating populations exposed to mutagens.

Fluorescence in situ hybridization determination of 22q12-q13 deletion in two intracerebral ependymomas

The sole cytogenetic abnormalities encountered in two childhood anaplastic intracerebral ependymomas were an isodicentric chromosome 22 in one case and an unbalanced chromosome 22 translocation associated with a partial deletion in the other. Fluorescence in situ hybridization analysis showed that the common 22q arm loss did not involve the rhabdoid region but included the EWS and NF2 loci. These results, in conjunction with data in the literature, suggest that the most frequently recurrent genomic loss in ependymomas does not involve the proximal 22q11.2 chromosome region but is localized distally to the hSNF5/INI1 locus. A tumor-suppressor gene, independent of the NF2 gene, which seems to be exclusively involved in intramedullary spinal cord ependymomas, might be implicated in the genesis of these intracranial tumors.

Telomere instability in a human cancer cell line

Telomere maintenance is essential in immortal cancer cells to compensate for DNA lost from the ends of chromosomes, to prevent chromosome fusion, and to facilitate chromosome segregation. However, the high rate of fusion of chromosomes near telomeres, termed telomere association, in many cancer cell lines has led to the proposal that some cancer cells may not efficiently perform telomere maintenance. Deficient telomere maintenance could play an important role in cancer because telomere associations and nondisjunction have been demonstrated to be mechanisms for genomic instability. To investigate this possibility, we have analyzed the telomeres of the human squamous cell carcinoma cell line SQ-9G, which has telomere associations in approximately 75% of the cells in the population. The absence of detectable telomeric repeat sequences at the sites of these telomere associations suggests that they result from telomere loss. The analysis of telomere length by quantitative in situ hybridization demonstrated that, compared to the human squamous cell carcinoma cell line SCC-61 which has few telomere associations, SQ-9G has more extensive heterogeneity in telomere length and more telomeres without detectable telomeric repeat sequences. The dynamics of the changes in telomere length also demonstrated a higher rate of fluctuation in telomere length, both on individual telomeres and coordinately on all telomeres. These results demonstrate that telomere maintenance can play a role in the genomic instability seen in cancer cells.

Fine mapping of an apparently targeted latent human herpesvirus type 6 integration site in chromosome band 17p13.3

An unusually high level of latent HHV-6 infection has been documented in the peripheral blood and/or bone marrow cells of a small group of patients with predominantly malignant lymphoid disorders, and in at least one healthy individual. We have shown previously in peripheral blood mononuclear cells (PBMCs) of three patients, two with a history of lymphoma and one with multiple sclerosis, a specific target site for latent integration of the full-length HHV-6 viral genome on the distal short arm of chromosome 17, in band p13.3. Fluorescence in situ hybridization (FISH) procedures were used to map more precisely the location of the viral integration site in one of those patients, relative to two known oncogenes mapped previously, namely CRK, and the more telomeric ABR oncogene. It is shown that the HHV-6 integration site is located at least 1,000 kb telomeric of ABR, and is very likely to map close to or within the telomeric sequences of 17p. This finding is significant given that human telomeric-like repeats flank the terminal ends of the HHV-6 genome. Cytogenetic studies showed evidence of karyotype instability in the peripheral blood cells infected latently.