Lipomatous differentiation in ependymomas: a report of three cases and comparison with similar changes reported in other central nervous system neoplasms of neuroectodermal origin

Giant cell glioblastoma with lipogenic differentiation in a patient with neurofibromatosis type 1: A case report

A 45-year-old woman with neurofibromatosis type 1 (NF1) developed a tumor in the left frontal lobe that showed features of giant cell glioblastoma (GC-GB). In addition to the typical GC-GB features, the tumor showed lipogenic differentiation, with many atypical lipoblasts and mature adipocytes. Tumor cells, including the lipogenic cells, were immunoreactive for GFAP, S-100 protein, ATRX, and p53. They were negative for IDH1-R132H, BRAF V600E, synaptophysin, NeuN, p16, mismatch repair proteins, and CD34. The patient is free from recurrence at approximately two years postoperatively. This is the fifth reported case of NF1-associated GC-GB (the second adult case). NF1 gene mutation might have played a role in the pathogenesis of lipogenic differentiation of GC-GB. The differential diagnosis of lipidized GC-GB from gliosarcoma or anaplastic pleomorphic xanthoastrocytoma is briefly discussed.

C11orf95-RELA, YAP1-MAMLD1, and YAP1-FAM118B Fusion Negative Anaplastic Ependymoma with Lipogenic Differentiation

Lipogenic differentiation in ependymoma is an infrequent occurrence with very few reported cases. The grading was done solely based on the histomorphology and molecular subtyping was not described in such ependymomas. New molecular classification divided ependymomas in nine different subgroups, of which supratentorial location tumor usually exhibits C11orf95-RELA, YAP1-MAMLD1, and YAP1-FAM118B fusion proteins. A 46-year-old female presented with headache and right-sided parapresis. Radilogy revealed a large intraxial left parietooccipital mass lesion, which histologically and immuohistochemically confirmed as anaplastic ependymoma with extensive lipogenic changes. The ependymal origin of the tumor was corroborated by the immunohistochemistry and ultrastructural studies. Molecular studies for C11orf95-RELA, YAP1-MAMLD1, and YAP1-FAM118B fusion proteins were negative. This is the first documentation of fusion negative supratentorial anaplastic ependymoma with lipogenic differentiation. This novel finding needs further reinforcement by similar studies to identify its impact on the disease outcome.

[Lipomatous ependymomas of the posterior fossa. An infrequent and little-known subtype. A case report and review of the literature]

Ependymomas are well defined glial tumours composed of uniform small cells with round nuclei in a fibrillar matrix. They have characteristic perivascular acellular areas (pseudorosettes) and, in some cases, ependymal rosettes. The three most well-known histological phenotypes are papillary, clear-cell and tanycytic. The WHO classification includes rare cases of ependymoma with lipomatous metaplasia. Lipomatous ependymomas of the posterior fossa are extremely rare; we only found 7reports of cases in adults. They usually arise in the fourth ventricle and may extend into the cerebellum, when they often show extensive vacuolization, pushing the nucleus to the periphery and giving rise to a signet-ring cell appearance. Radiologically, there are few findings characteristic of these tumours. Immunohistochemistry is essential to differentiate this subtype from other more common lesions, such as metastatic adenocarcinoma, especially from breast, intestine and kidney.

Sarcomatous Change of Cerebellopontine Angle Ependymoma Following Radiosurgery: A Case Report

Sarcomatous change in ependymal tumors is rare and has been poorly described. We report on a cerebellopontine angle lesion that demonstrated rapid progression two years after radiosurgery in a 73-year-old female patient. Histopathological diagnosis at clinical progression showed an ependymoma with sarcomatous change (“ependymosarcoma”) that was believed to be due to radiation. The patient underwent a complex tumor resection without complications using an exhaustive multi-modal neuromonitoring paradigm throughout the dissection and resection of the tumor. Given the limited available data on these rare tumors, we review their presentation, imaging, and histopathology in the context of the previous literature, and also discuss the management of these lesions in the cerebellopontine angle.

Supratentorial Extraventricular Ependymomas: Imaging Features and the Added Value of Apparent Diffusion Coefficient

OBJECTIVE

To improve the understanding and the diagnosis of intracranial ependymal tumors.

METHODS

The clinical, radiological and prognostic features of 48 supratentorial extraventricular ependymomas and 74 intraventricular ependymomas were summarized and compared.

RESULTS

Supratentorial extraventricular ependymomas, most often located in the frontal lobe (33.3%) and classified as grade III (75.0%), had relatively large eccentric cysts (3.07 ± 2.03 cm), significant enhancement (84.8%), low apparent diffusion coefficient (ADC) values, and associated with higher mortality (41.3%). The majority of intraventricular lesions occurred in the fourth ventricle (86.5%) and classified as grade II (78.4%), had relatively small and multiple cystic changes (1.04 ± 0.87 cm), slight or moderate enhancement (76.9%), high ADC values and associated with lower mortality (20.7%). There were few significant differences between grade II and grade III tumors in these 2 groups, respectively. Young age, high grade and low ADC values are worse prognostic indicators for patients with supratentorial extraventricular ependymomas, but not for those with intraventricular ependymomas.

CONCLUSIONS

Conventional radiological features, combined with clinical manifestations and quantitative information provided by diffusion-weighted imaging, may not only enhance the diagnosis and assist in determining prognosis but also provide a better pathophysiological understanding of intracranial ependymal tumors.

L1CAM Immunopositivity in Anaplastic Supratentorial Ependymomas: Correlation With Clinical and Histological Parameters

Supratentorial ependymomas (ST EPNs) are molecularly characterized, of which the RELA fusion positive tumors are the most common and aggressive subgroup. Moreover, histologically, anaplastic ST EPN (ST-AE) often mimic other central nervous system primary high-grade tumors resulting in a diagnostic dilemma. We aimed to study a cohort of ST-AE; evaluate the expression of two RELA fusion-associated markers—L1CAM and p65 (NF-κB); and correlate their expression with clinical and histological parameters. Cases of ST-AE diagnosed in our department from January 2011 to June 2016 (n = 72) were reviewed. A battery of immunohistochemical markers was employed. A total of 65 confirmed ST-AE were included in the study. Age ranged from 9 months to 60 years. There was a slight predominance in the pediatric population (57%). Male-to-female ratio was 1:1.16. Histomorphological features were varied and mimicked other high-grade tumors in several cases. L1CAM immunopositive tumors constituted 26% of cases and were predominantly seen in young children, in the frontoparietal location, and exhibited clear cell morphology with calcification. A consistent pattern of L1CAM immunopositivity was noted in paired primary and recurrent tumor samples. Our study portrays the varied clinical and histomorphological spectrum of ST-AE. The study emphasizes the association of L1CAM immunopositivity with a wide spectrum of histological parameters, literature on which is scant till date. Since ST EPN-RELA are tumors with aggressive behavior, such a correlation would be clinically relevant, particularly when there is limited access to molecular testing.

Pilocytic Astrocytoma with Adipocytic Differentiation: A Rare Histological Variation

Lipidization of the low-grade astrocytic tumor is a very rare phenomenon. We report a case of pilocytic astrocytoma with adipocytic differentiation involving the left cerebellar hemisphere and pontis in an 11-year-old boy. Till date, very few such cases have been reported in children. A young boy presented with a clinical picture suggestive of cerebellar dysfunction since 7 months. Imaging revealed a mass lesion involving the left cerebellar hemisphere measuring 4.5×4.1cm. Subtotal excision of the tumor was carried out. Microscopic features were typical of pilocytic astrocytoma but with extensive lipidization of tumor cells. Immunohistochemically, the tumor cells were immunoreactive to glial fibrillary acidic protein, S-100, and immunonegative to p53 and isocitrate dehydrogenase 1. Ki-67 labeling index was 1%. The patient had an uneventful postoperative period and is doing well on follow-up. An extensive review of prior work was carried out to elucidate the clinicopathologic significance of this entity, if any, with special reference to the pediatric age group.

Clinicopathological and imaging features of lipoastrocytoma: Case report

Lipidized tumors of the central nervous system are very uncommon, with only a few cases described. We report a case of a 25-year-old woman with a tumor involving the left premotor area. She underwent gross total excision. Histologically, the tumor was composed of glial fibrillary acidic protein-positive glial cells with areas of lipidization. A diagnosis of lipoastrocytoma was rendered. At three-year follow-up she was doing well, supporting the presumed favorable prognosis of these uncommon tumors. Absence of xanthochromic appearance, mitotic activity, necrosis and poor reticulin activity are the differentiating features from the pleomorphic xanthoastrocytoma. We highlighted that these tumors involve the adult and pediatric population and distribute in both supratentorial and infratentorial compartments as well as in the spinal cord.

Lipomatous/Extensively Vacuolated Ependymoma with Signet-Ring Cell-Like Appearance: Analysis of a Case with Extensive Literature Review

"Lipomatous" and "extensively vacuolated" are descriptive captions that have been used to portray a curious subset of ependymomas distinctively bearing cells with a large vacuole pushing the nucleus to the periphery and, thus, simulating a signet-ring cell appearance. Here, we would like to report the first ependymoma of this kind in a Latin American institution. A 16-year-old boy experienced cephalea during three months. Magnetic resonance imaging scans showed a left paraventricular tumour which corresponded to anaplastic ependymoma. Intriguingly, it was also composed of cells with single or multiple hollow cytoplasmic vacuoles sometimes giving a signet-ring cell-like configuration. Immunolabeling of these showed membrane positivity for GFAP, PS100, and CD99, while Ki-67 expression was null. Ultrastructural examination of retrieved paraffin-embedded tissue showed the presence of scarce microlumina filled with microvilli but failed to demonstrate any content in such optically empty vacuoles as only scant granulofibrillary debris was observed. A schism prevails at present regarding these unusual morphological variants, being either "lipomatous" or "vacuolated" based mainly on the EMA immunoprofile. This, however, is a misappropriate approaching. Could it be that perhaps we are dealing with the same histopathological entity or it may simply happen that fixation and artefacts cannot allow for their proper identification?

Spinal Intradural, Extramedullary Ependymoma with Astrocytoma Component: A Case Report and Review of the Literature

Ependymomas are common spinal lesions, with the vast majority arising in an intramedullary location. Several cases have been described in the literature of ependymomas in an intradural, extramedullary location. The authors present a case of a 56-year-old female who presented with several weeks of lower back pain and weakness. MRI revealed an intradural, extramedullary enhancing mass at L1-L2. The mass was successfully resected surgically. Pathologic evaluation revealed a low grade glioma with components of both ependymoma and pilocytic astrocytoma with MUTYH G382D mutation. Extramedullary ependymomas are very rare tumors. To the authors' knowledge, this is the first case of ependymoma/astrocytoma collision tumors described in an extramedullary location.

Lipoastrocytoma: A rare case report and review of literature

Lipoastrocytoma is an extremely rare tumor, with only a few cases described. We report a case of a low-grade astrocytoma occupying the right cortical lobe in the parafalcine location. The patient was admitted with headache, vomiting and altered sensorium for duration of 1 year. MRI revealed a large heterogeneous enhancing mass in the right fronto-parieto-temporal lobe with intratumoral fat along with cystic changes and calcification (correlated with CT) showing mass effect in the third ventricle. A gross total excision of the tumor was performed. Histologically, the tumor showed glial cells that contained lipid droplets coalescing into a single large droplet, similar in appeareance to adipocytes. Immunohistocemically, tumor cells strongly expressed GFAP and S-100 protein. Ki-67 labelling index was low. The patient remained in good neurological condition at 3 months follow-up. This case represents a rare variant of low-grade astrocytoma that is designated as lipoastrocytoma.

Cerebellar Liponeurocytoma

Cerebellar liponeurocytoma is a rare neoplasm with distinctive morphologic features. It typically involves the cerebellar hemispheres of middle-aged to older adults. The tumor is composed of a uniform population of neurocytic cells possessing round to oval nuclei and pale to clear cytoplasm. A variable degree of lipidization of the tumor cells is present, lending a resemblance to mature adipose tissue. Immunohistochemistry serves to confirm the neurocytic differentiation of the tumor cells. In the 2007 revision of the World Health Organization classification of central nervous system tumors, cerebellar liponeurocytoma was reclassified as a grade II neoplasm to reflect a higher recurrence rate than was previously appreciated.

Lipidized glioblastoma: pathological and molecular characteristics

We report a rare case of a 33-year-old man with a lipidized glioblastoma multiforme (GBM) in the right posterior frontal region. Histologically the tumor had all the typical features of a GBM but with the rare observation of lipidized differentiation. There were multiple mitoses, extensive vascular proliferation, focal necrosis and the tumor cells had abundant xanthomatous cytoplasm and marked nuclear pleomorphism. The tumor showed immunoreactivity with GFAP. The O(6) - methylguanine methyltransferase (MGMT) promoter was methylated and there were no isocitrate dehydrogenase (IDH)1 and IDH2 mutations. To the best of our knowledge, this is the first time MGMT promoter status and IDH mutation assessment have been reported in a case of lipidized GBM.

Rare histological variants in ependymomas: histopathological analysis of 13 cases

Ependymomas are rare brain tumors representing about 3% of all intra-cerebral and spinal neoplasms. The WHO classification recognizes various rare histological ependymoma variants (i.e., lipidized ependymoma, giant cell ependymoma, etc.). However, a detailed analysis of a larger series of such cases is still lacking. We analyzed 13 case of ependymoma presenting unusual histological features. The data analysis of our series and its comparison to the cases published in literature did not reveal any close association between these features and the clinical parameters (such as age or localization). Moreover, some of these features can be found combined in individual tumors, suggesting that these variants may represent a spectrum of differentiation rather than true specific entities. However, awareness on these rare histological patterns in ependymomas is necessary in the differential diagnosis with other primary or secondary brain tumors.

Unclassified glioneuronal tumor with advanced lipidization

Lipidization is observed only occasionally in primary neuroectodermal tumors of the central nervous system. It may reflect lipomatous transformation of tumor cells into xanthomatous and/or adipocyte-like cells. We report a unique case of mixed glioneuronal tumor with marked lipomatous changes in a young patient with intractable epilepsy. MRI revealed a well-circumscribed lesion in the right temporal lobe. Histopathological findings showed the pleomorphic tumor with numerous cells containing large lipid droplets, resembling mature adipocytes, that were arranged in clusters or scattered within the neoplastic tissue. The tumor was composed of both glial and neuronal elements. Some tumor cells displayed features intermediate between glial and neuronal cells. The reticulin fibers were limited to blood vessels. Mitotic figures, vascular proliferation, and necrosis were absent, and MIB-1 labeling index was less than 1%. Diffuse immunoreactivity for GFAP and S100-protein was observed. In some heavily lipidized cells, the lipid droplets were surrounded by a cytoplasmic rim of GFAP immunoreactivity. Numerous cells exhibited immunostaining for NSE and synaptophysin. This is the first documented case of glioneuronal tumor with extensive lipomatous transformation, which might be considered as a heavily lipidized unclassified pleomorphic glioneuronal tumor or a variant of lipoganglioglioma with marked pleomorphism and severe lipidization.

Glycogen-rich pleomorphic xanthoastrocytoma with clear-cell features: confirmatory report of a rare variant with implications for differential diagnosis

Central nervous system space-occupying lesions with clear-cell features encompass a nosologically heterogeneous array, ranging from reactive histiocytic proliferations to neuroepithelial or meningothelial neoplasms of various grades and to metastases. In the face of such differential diagnostic breadth, recognizing cytoplasmic lucency as part of the morphological spectrum of some low grade gliomas will directly have an impact on patient care. We describe a prevailing clear-cell change in an epileptogenic left temporal pleomorphic xanthoastrocytoma surgically resected from a 36-year-old man. Mostly subarachnoid and focally calcified, the tumor was composed of fascicles of moderately atypical spindle cells with optically lucent cytoplasm that tended to intermingle with a desmoplastic mesh of reticulin fibers. Immunohistochemically, coexpression of S100 protein, vimentin, GFAP, and CD34 was noted. Conversely, neither punctate staining for EMA nor positivity for CD68 was seen. Mitotic activity was absent, and the MIB1 labeling index was 2-3% on average. Diastase-sensitive PAS-positive granula indicated clear-cell change to proceed from glycogen storage. Electron microscopy showed tumor cell cytoplasm to be largely obliterated by non-lysosomal-bound pools of glycogen, while hardly any fat vacuole was encountered. Neither ependymal-derived organelles nor annular lamellae suggesting oligodendroglial differentiation were detected. The latter differential diagnosis was further invalidated by lack of codeletion of chromosomal regions 1p36 and 19q13 on molecular genetic testing. By significantly interfering with pattern recognition as an implicit approach in histopathology, clear-cell change in pleomorphic xanthoastrocytoma is likely to suspend its status as a "classic", and to prompt more deductive differential diagnostic strategies to exclude look-alikes, especially clear-cell ependymoma and oligodendroglioma.

Lipoglioblastoma: a lipidized glioma radiologically and histologically mimicking adipose tissue

BACKGROUND

We report the case of a man with glioblastoma containing a component radiologically and histologically mimicking adipose tissue.

CASE DESCRIPTION

A 48-year-old man recently complaining of headaches and difficulty with speech presented with a cystic peripherally enhancing left temporoparietal mass with focal intrinsically (precontrast) bright nodules in fluid attenuated inversion recovery and T1-weighted images similar to adipose tissue. Histologically, the enhancing component was classic glioblastoma, whereas the bright nodules comprised tumor cells that in aggregate closely resembled adipose tissue.

CONCLUSIONS

The case illustrates the extent to which lipidized central nervous system tumors of glial origin, or components thereof, can radiologically and histologically resemble adipose tissue. However, immunohistochemical staining and electron microscopy can eliminate diagnostic confusion.

A clinicopathological, immunohistochemical and neuroradiological study of eight patients with central neurocytoma

Central neurocytomas are low-grade tumors of neuronal origin located in the lateral ventricle that present predominantly with raised intracranial pressure. In this retrospective study, we investigated the clinical, radiological, histopathological and immunohistochemical features of eight patients (seven males and one female; age range 16-61 years; mean=35.1 years) with neurocytoma. Raised intracranial pressure was the most common presenting feature. In addition, one patient presented with marked visual deterioration and one presented with a visual field defect. All lesions were located in the lateral ventricle (right lateral ventricle: four patients, left lateral ventricle: three patients, both ventricles: one patients). Radiology showed marked intratumoral calcification in two patients. Total microsurgical excision was achieved in seven patients. Histopathology showed sheets of monotonously small-to-medium-sized neoplastic cells with uniform round-to-oval nuclei and inconspicuous nucleoli. Immunohistochemistry was positive for synaptophysin and neuron-specific enolase (NSE) in all tumors, and glial fibrillary acidic protein was focally positive in two patients. One patient had lipomatous differentiation within the tumor. No recurrence was noted in any of our patients until the last follow-up; however, there were two deaths in our series.

Lipoastrocytoma: Case report and review of the literature

Lipoastrocytoma is an extremely rare tumor, with only six cases described. We report the case of an astrocytoma involving the upper part of the cerebellar-pontine angle and the right portion of the clivus starting from the brainstem with a diffuse lipomatous component in a 39 year-old man. The patient was admitted with headache of 1 year's duration and diplopia over the previous 3 months. MRI revealed a ponto-cerebellar lesion that showed irregular enhancement after contrast administration. Subtotal excision of the tumor was accomplished. Adjuvant chemotherapy and radiation therapy were not administered. Histologically the tumor showed the classical histology of low-grade astrocytoma and a portion of the lesion was composed of lipid-laden cells. Immunohistochemistry for glial fibrillary acid and S-100 proteins clearly demonstrated the glial nature of these cells. Ki-67/Mib-1 labeling index was low (2%). The patient remains in good neurological conditions after 10 months. Our case has a benign postoperative behavior, also after subtotal excision, with restrictions due to the short follow-up. It is important to record each new case of this rare tumor to produce a better characterization of this lesion.

Glioblastoma with adipocyte-like tumor cell differentiation--histological and molecular features of a rare differentiation pattern

We report on three adult patients with primary glioblastomas showing prominent adipocytic (lipomatous) differentiation, hence referred to as "glioblastomas with adipocyte-like tumor cell differentiation." Histologically, the tumors demonstrated typical features of glioblastoma but additionally contained areas consisting of glial fibrillary acidic protein (GFAP)-positive astrocytic tumor cells resembling adipocytes, that is, containing large intracellular lipid vacuoles. Comparative genomic hybridization (CGH) and focused molecular genetic analyses demonstrated gains of chromosomes 7, losses of chromosomes 9 and 10, as well as homozygous deletion of p14(ARF) in one of the tumors. The second tumor showed gains of chromosomes 3, 4, 8q and 12 as well as losses of chromosomes 10, 13, 15q, 19 and 22. In addition, this tumor carried homozygous deletions of CDKN2A and p14(ARF) as well as point mutations in the TP53 and PTEN genes. The third tumor also had a mutation in the PTEN gene. None of the tumors demonstrated EGFR, CDK4 or MDM2 amplification. Taken together, our results define a rare glioblastoma differentiation pattern and indicate that glioblastomas with adipocyte-like tumor cell differentiation share common molecular genetic features with other primary glioblastomas.

Ependymal tumors

Ependymomas represent a heterogeneous group of glial tumors whose biological behavior depends on various histological, molecular, and clinical variables. The scope of this chapter is to review the clinical and histo-logical features as well as the molecular genetics of ependymomas with special emphasis on their influence on tumor recurrence and prognosis. Furthermore, potential molecular targets for therapy are outlined.

A 32-year-old man with a fourth ventricular mass

Lipoastrocytomas are rare and only four cases have been reported previously. Our case is in the fourth ventricle of a 32 year-old man.Many areas showed tumor cells with a signet-ring appearance and focally formed perivascular arrangements. Eosinophilic granular bodies were frequent. There was strong positive immunoreactivity to GFAP and S-100 protein, even in those vacuolated tumor cells.The proliferation index was less than 10%. Ultrastructural studies showed that the signet-ring cells had large lipid droplets as well as intermediate filaments. Ultrastructural features characteristic of ependymomas were not seen. These findings confirm that the vacuoles were lipid droplets in astrocytic tumor cells. The features noted are suggestive of a probable better prognosis in this variant of low-grade astrocytoma.

Giant cell ependymoma of the cervical spinal cord: case report and review of the literature

Ependymomas account for 2-6% of all central nervous system neoplasms. They develop from the ependymal cells that line the ventricular cavities of the brain and the central canal of the spinal cord, as well as from ependymal clusters in the filum terminale. Giant cell ependymoma (GCE) is a rare subtype, with few cases reported, mostly in the brain. We describe the case of a cervical spinal cord ependymoma with pleomorphic giant cells and focal calcifications occurring in a 25-year-old woman. Magnetic resonance imaging revealed a large multicystic and partially enhancing intramedullary tumour extending from C2 to C5. Intraoperative analysis of frozen section tissue fragments suggested a malignant tumour; however, an obvious cleavage plane was present around most of the mass, and a macroscopically complete tumour removal could be achieved. Subsequently, paraffin sections and immunohistochemical investigations revealed unequivocal evidence of a GCE with focal calcifications. This case, the second giant-cell ependymoma to be described in the spinal cord and the first with focal calcifications, highlights the features of GCE and the discrepancy between the worrisome histological appearance, the surgical findings and the clinical relatively good prognosis.

Immunohistochemistry of gliosarcoma with liposarcomatous differentiation

A case of gliosarcoma composed of glioblastoma and liposarcoma is presented. A 70-year-old Japanese man was admitted to hospital because of dysarthria and aphasia. Magnetic resonance imaging indicated a brain tumor located in the temporal-parietal area of the left hemisphere. He rejected any therapy and died of respiratory failure. At autopsy the tumor was well-demarcated with firm consistency and myxoid appearance, accompanied by necrosis and hemorrhage. Microscopically the tumor consisted of both glial and sarcomatous components, compatible with a gliosarcoma. Lipoblast-like tumor cells were identified in the sarcomatous area. Glial component was observed in the periphery and was diffusely positive for CD56 and S100 protein and focally for glial fibrillary acidic protein. Only a small number of tumor cells in the sarcomatous area expressed neurogenic markers. Lipoblast-like tumor cells were positive for S100 protein but negative for any other neurogenic markers. A significant number of tumor cells were positive for retinoblastoma protein (pRB) in the glial area, whereas only a few of them were positive in the sarcomatous area, indicating alteration of pRB in sarcomatous component. The present tumor is a rare gliosarcoma with liposarcomatous differentiation; alteration of pRB may play a role in sarcomatous transformation of glial component.

Ependymal tumors with sarcomatous change ("ependymosarcoma"): a clinicopathologic and molecular cytogenetic study

Gliosarcomas are uncommon primary tumors of the central nervous system defined as exhibiting both glial and sarcomatous components. Sarcomatous change occurring in ependymal tumors is rare. We identified 11 such examples. There were 6 female and 5 male patients (median age, 18 y; range, 2 to 63). The tumors were located in the parieto-occipital (n=2), temporal (n=1), parietal (n=1), frontal (n=1), and occipital lobes (n=1), as well as the lateral ventricles (n=2), insula (n=1), cerebellopontine angle (n=1), and fourth ventricle/cerebellopontine angle (n=1). At presentation, the sarcomatous component was noted in 6 (of 10) cases and the ependymal element was grade III in 7 and grade II in 3 tumors, respectively. The sarcomatous component consisted of a reticulin rich, glial fibrillary acidic protein-negative fibrosarcoma (n=5) or pleomorphic spindle cell sarcoma (n=3), and 2 examples with heterologous elements: osseous and cartilaginous (n=1) and osseous only (n=1). The single case involving the fourth ventricle/left cerebellopontine angle consisted of subependymoma and fibrosarcoma components in roughly equal proportions at presentation. Fluorescence in situ hybridization studies performed with probes targeting the NF2 gene and other members of the protein 4.1 gene family demonstrated similar alterations in the ependymal and sarcomatous components in the cases tested, including polysomies/polyploidy (n=3), gains of 1q (n=3), deletions of 22q (n=2) and 6q (n=1), and monosomy 18 (n=1). There was no evidence of MDM2 or CCND1 amplification in any of the cases tested. On follow-up, 5 patients expired 4 months to 18 years after initial resection and 4 to 11 months after development of the sarcomatous component (mean, 7.6 mo); 1 patient is alive at 5 years with recurrent disease, and 1 is alive without recurrence 12 years after initial gross total resection followed by radiation therapy. Although rare, ependymal neoplasms must be included among the gliomas prone to undergo sarcomatous change and we propose the term "ependymosarcoma" for these tumors.

Ependymoma and intraparenchymal calcifying pseudoneoplasm of the neural axis: incidental collision or unique reactive phenomenon?

The so-called "calcifying pseudoneoplasm of the neural axis" is a rare tumefactive lesion presumed to be reactive in nature. To our knowledge, association with a true neoplasm has not been previously reported. We recently encountered the case of a 67-year-old woman who underwent resection of an incidentally discovered cerebellar cystic mass with a distinct, calcified component. Histology demonstrated a partially ossified, lobulated, chondrocalcific lesion surrounded by chronic inflammation, spindle to epithelioid cells, and occasional multinucleated giant cells-all features of calcifying pseudoneoplasm of the neural axis. A low-grade ependymoma associated with marked piloid gliosis was found contiguous to the lesion. The unique combination of an ependymoma with marked reactive gliosis and a calcifying pseudoneoplasm supports the reactive nature of the latter.

Highly cystic brain tumor: rare histological features in an ependymoma

Ependymoma is a slowly growing tumor appearing mostly in children and young adults. Several histological patterns are described. We report a case with unusual microscopic features, composed mostly of multiple cysts. Ultrastructural and immunohistochemical examination confirmed the diagnosis. Neuropathologists should be aware of this particular change which can generate some diagnostic difficulties.

Concomitant Conus Medullaris Ependymoma and Filum Terminale Lipoma: Case Report

OBJECTIVE:

Ependymomas of the conus medullaris-cauda equina-filum terminale region are typically solitary lesions. In this report, we describe the clinical presentation, radiographic findings, operative details, and pathological features of a patient with a conus medullaris ependymoma and a filum terminale lipoma.

CLINICAL PRESENTATION:

A 40-year-old woman presented with increasing low back pain and bowel and bladder dysfunction. Magnetic resonance imaging revealed a partially cystic enhancing lesion at the conus medullaris and a T1-weighted hyperintense mass within the filum terminale.

INTERVENTION:

An L2-L3 laminotomy/laminoplasty was performed for gross total resection of the mass. Histopathological examination demonstrated a conus medullaris ependymoma and filum terminale lipoma. The patient experienced complete resolution of her preoperative symptoms.

CONCLUSION:

Spinal cord ependymomas are almost exclusively single lesions and their coexistence with other pathological entities is rare. In this report, we describe a patient with a concomitant conus medullaris ependymoma and filum terminale lipoma.

Signet-ring cell ependymoma with intratumoral hemorrhage in the medulla oblongata

We report a case of signet-ring cell ependymoma of the medulla oblongata. The patient presented with acute paralysis of the soft palate and absent gag reflex resulting in respiratory distress after accidental inhalation of water. MRI revealed a large intra-axial mass with foci of intratumoral hemorrhage in the medulla oblongata. A subtotal resection was performed as histopathological findings on the frozen section were consistent with metastatic carcinoma. However, the final paraffin section showed an ependymoma with signet-ring cells. A total removal was then performed with preservation of the lower cranial nerves. Postoperatively, the patient made a slow but steady recovery, and was able to swallow both water and food within 3 months. Signet-ring cell ependymoma must be included in the differential diagnosis of metastatic carcinoma to the central nervous system.

[Intramedullary lipomatous ependymoma: case report]

A 51 year-old man was admitted to our hospital with poor general health and neurological disturbances with paresthesia, dysuria and defecation disorder. Neuroimaging showed a syringomyelia cyst from C1 to conus medullaris, together with a intramedullar tumoral mass in T6-T7. Histological examination of the surgical specimen led to the diagnosis of lipomatous ependymoma.

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.

Cerebellar liponeurocytoma: Morphological, immunohistochemical, and ultrastructural study of a relapsed case

Cerebellar liponeurocytoma is a rare and newly identified neoplasm found in adults which is reputed to be benign. Its salient morphological characteristics are advanced neuronal/neurocytic differentiation, the presence of lipomatous areas, low mitotic rate, and the absence of necrosis, pleomorphism and vascular hyperplasia. Reported is a case of relapsing liponeurocytoma which occurred 3 and a half years after the radical excision of the primary lesion. Histopathological aggressive features (mitoses and a high proliferation index as evaluated by MIB-1) were shown in the primary lesion and recurrence of the tumor. We suggest that liponeurocytoma is an uncertain malignant potential lesion when mitoses are present and the MIB-1 positive cells are more than 10%.

Fourth ventricle neurocytoma with lipomatous and ependymal differentiation

We report the case of a 4-year-old girl with a fourth ventricle tumor diagnosed as a cerebellar liponeurocytoma which recurred, showing ependymal differentiation, 14 months after surgery. Magnetic resonance imaging at initial presentation revealed a large mass in the fourth ventricle, and histology showed a neoplasm characterized by a combination of well-differentiated neurocytes and cells resembling adipocytes. The tumor recurrence was histologically identical to the original tumor in some regions, but with fewer adipose-like cells, while other areas presented an endocrine architecture with oligo-like or pleiomorphic cells, and rosette-like arrangements of tumoral cells were seen around the thin vessels, with features similar to cellular ependymoma. The cells in the liponeurocytoma areas expressed synaptophysin, chromogranin A, and epithelial membrane antigen. Glial fibrillary acidic protein was expressed in some dispersed tumoral cells, in lipidized tumoral cells, and in reactive astrocytes. Cytokeratin was focally expressed in the ependymal region of the recurrence. The immunophenotype of our case, with glial, ependymal, and neuronal or neuroendocrine markers, suggest a neurocytoma with lipomatous and ependymal differentiation. This tumor resembled those derived from circumventricular organs. Its localization in the area postrema region led us to hypothesize that it may be derived from this circumventricular organ.

Cerebellar liponeurocytoma/lipidized medulloblastoma

Cerebellar liponeurocytoma that has been recently identified as a distinct entity by the World Health Organization is characterized by areas of lipomatous differentiation and apparently by a favorable prognosis. In this paper, we described a case of 49-year-old female showing progressive clinical course inspite of a low labeling/mitotic index. We also review the relevant literature. Although, basically all reported cases share a similar histological pattern, i.e. focal accumulations of adiposities in an otherwise typical small cell tumor like central neurocytoma, some clinical properties such as (age, proliferative potential, therapy and survival) are not uniform. The exact biological behavior of this special variant tumor is established. Yet, this needs further confirmation on a large number of cases with longer follow-up periods.

Problematic differential diagnosis between cerebellar liponeurocytoma and anaplastic oligodendroglioma

A cerebellar tumour, first diagnosed as an anaplastic oligodendroglioma, received radiation therapy (45 Gy) following gross total resection. The second histological study revealed a liponeurocytoma, a benign tumour not requiring adjuvant therapy. This case emphasizes the importance of considering this diagnosis to prevent unnecessary irradiation of such rumours.

Emerging Tumor Entities and Variants of CNS Neoplasms

Since the appearance in 2000 of the World Health Organization (WHO) classification for central nervous system (CNS) neoplasms, numerous descriptions of new entities or variants have appeared in the literature. In the group of neuronal and mixed glioneuronal neoplasms are lesions with distinctive morphological features that are still not included in a precise classification, including extraventricular neurocytoma, papillary glioneuronal tumor, rosette-forming glioneuronal of the fourth ventricle, glioneuronal with neuropil-like rosette, and DNT-like tumor of the septum pellucidum. The glioneuronal tumor with neuropil-like rosette and oligodendroglioma with neurocytic differentiation represent morphological variants of genetically proven diffuse gliomas. The lipoastrocytoma and the pilomixoid astrocytoma enlarge the group of astrocytic lesions. Rare, low-grade gliomas of the spinal cord with extensive leptomeningeal dissemination associated with unusual neuroimaging are described. The chordoid glioma of the third ventricle and the papillary tumor of the pineal region seem to be correlated by a common histogenesis from the specialized ependyma of the subcommissural organ. An embryonal tumor with neuropil and true rosettes combining features of neuroblastoma and ependymoblastoma is discussed. These new, recently described lesions indicate that the complex morphologic spectrum of CNS tumors is far from being completely delineated.

Giant cell ependymoma of the spinal cord. Case report and review of the literature

Several rare histological variants of ependymoma have been described. The authors report on a patient in whom cervical spinal cord astrocytoma was originally diagnosed after evaluation of a limited biopsy specimen. More abundant tissue obtained during gross-total resection included areas of well-differentiated ependymoma. The histological features of the tumor were extremely unusual, with a major component of pleomorphic giant cells. Its histological, immunohistochemical, and electron microscopic features, however, were consistent with ependymoma. Only two cases of terminal filum and two of supratentorial giant cell variant of ependymoma have been reported. To the authors' knowledge, this represents the first case of giant cell ependymoma of the spinal cord. The clinical significance is the potential for misdiagnosis with anaplastic (gemistocytic) astrocytoma, especially in cases in whom limited biopsy samples have been obtained.

Highly anaplastic extraventricular ependymoma arising in an adult, mimicking metastatic adenocarcinoma with heavy stromal inflammation and emperiporesis

We report a case of extraventricular ependymoma arising in a 50-year-old woman that took an aggressive clinical course with recurrence three times. The initial tumor was a well-circumscribed nodule in the right temporal white matter measuring 2 cm in diameter. It showed variegated histological findings mimicking metastatic adenocarcinoma: an epithelioid arrangement of highly pleomorphic cells with pseudopapillary structures and perivascular pseudorosettes, and bizarre multinucleated giant cells with occasional emperiporesis surrounded by abundant mononuclear inflammatory cells, as well as a focal small area of conventional ependymoma. Emperiporesis and abundant mononuclear cell infiltration were not previously described in an ependymoma. The recurrent tumors predominantly showed an epithelioid pattern with frequent formation of astroblastoma-like pseudopapillary structures. Neoplastic cells were markedly atypical and had characteristic intracytoplasmic eosinophilic inclusion bodies. Much of the cells in both the initial and recurrent tumors showed a positive immunostaining for glial fibrillary acidic protein (GFAP) with accentuation to the cytoplasmic processes of the pseudorosettes and pseudopapillary structures. Epithelial membrane antigen (EMA) highlighted the epithelial differentiation of the tumor cells, while cytokeratin was completely negative. Although this tumor might be classified to at least WHO grade III from the histology and aggressive behavior, the exact grading is still controversial because of the rarity of such cases.