Chordoid glioma of the third ventricle: a report of two cases, one with ultrastructural findings.

Chordoid glioma, which generally occurs in adults, is a rare CNS tumor arising in the anterior part of the third ventricle. We report two cases of chordoid glioma of the third ventricle in a 42-year-old woman and a 51-year-old man, respectively. Both tumors showed essentially the same histological and immunohistochemical features; the tumors were composed of cords and nests of epithelioid, GFAP-immunoreactive cells in a mucinous stroma with lymphoplasmacytic infiltrates at the tumor periphery. Ultrastructural examination in one case revealed that the tumor cells were characterized by the presence of hemidesmosomes and associated focal basal lamina formation, intermediate junctions, microvilli and cilia, and intercellular microrosettes with microvilli. Of interest was that small blood vessels with fenestrated endothelial cells were present in the stroma. In the brain, the presence of fenestrated endothelial cells is a feature of the circumventricular organs (except the subcommissural organ), among which the organum vasculosum of the lamina terminalis is located in the anterior part of the third ventricular floor that is lined by specialized ependymal cells known as tanycytes. These findings further strengthen the hypothesis that chordoid glioma may represent a peculiar clinicopathological subtype of ependymoma (chordoid ependymoma) originating from the lamina terminalis area.

Subependymal giant cell astrocytoma (SEGA): Is it an astrocytoma? Morphological, immunohistochemical and ultrastructural study.

Subependymal giant-cell astrocytoma (SEGA) is a rare intra-ventricular low-grade tumor which frequently occurs as a manifestation of tuberous sclerosis complex. The histogenesis of SEGA is controversial and its astrocytic nature has been doubted. First studies suggested the astrocytic nature of SEGA while several recent reports demonstrate its glio-neuronal nature. In spite of this, in the recently revised WHO classification of the CNS tumors, SEGA has been still included in the group of astrocytomas. We studied nine tuberous sclerosis complex-associated SEGAs. Patients were 1-18 years old. Eight patients (89%) had a solitary lesion located in the lateral ventricle close to of the head of the caudate nucleus, the remaining patient (11%) had two tumors, one located close to the head of the left caudate nucleus and the other in the central part of the right lateral ventricle. Histologically, tumors were composed of three types of cells: spindle, gemistocytic and ganglion-like. Four tumors (44%) had a prominent vascularization and three (33%) showed an angiocentric pattern. Calcifications were observed in six cases (66%). By immunohistochemistry, the majority of the tumors were GFAP- (9; 100%), neurofilament- (8, 89%), neuron-specific enolase- (9, 100%), and synaptophysin- (8; 89%) positive. Ultrastructural studies were performed on four cases. In all four there were glial cell processes filled with intermediate filaments. In one case dense core putative neurosecretory granules were appreciable. Our results emphasize the glio-neuronal nature of SEGA. We suggest moving it into the group of mixed glio-neuronal tumors under the denomination of subependymal giant cell tumor.

Ultrastructural evidence of ependymal differentiation in a genetically proven atypical teratoid/rhabdoid tumor.

INTRODUCTION: We describe a case of genetically proven atypical teratoid/rhabdoid tumor (ATRT), showing ultrastructural evidence of ependymal differentiation. Such differentiation has not been reported so far in ATRT. CONCLUSION: This finding supports the concept that ATRTs as the majority of central nervous system embryonal tumors may derive from an immature and pluripotent neuroectodermal cell capable of differentiating along multiple lineages.

Three-dimensional reconstructive analysis of intracytoplasmic lumina found in ependymomas.

Three-dimensional reconstructive analyses revealed that the intracytoplasmic lumina found in ependymomas were actually formed by subsidence of an extracellular membrane, resembling a volcano. This finding was compatible with cytologic and electron microscopic findings. In addition, there were many tiny thorns resembling a holly leaf on the extracellular membrane, such that cilia and microvilli on the cellular membrane discontinued cell-to-cell tight junctions.

Ultrastructural study of neuronal and related tumors in the ventricles.

Intraventricular tumors may arise from a variety of cells in the region. There are some difficulties in diagnosing these tumors because of their histologically similar appearance. We analyzed intraventricular tumors, including central neurocytoma, oligodendroglioma, cerebral neuroblastoma, and cerebellar neuroblastoma, the neuronal characters of which were established based on their ultrastructural findings, except for oligodendroglioma. Central neurocytoma and cerebellar neuroblastoma showed synaptic formation, and cerebral neuroblastoma possessed immature neurites. Oligodendroglioma showed similar structures to that of a normal oligodendrocyte. Furthermore, we review the literature and evaluate the usefulness of analyzing ultrastructures.

Medulloblastoma demonstrating multipotent differentiation: case report.

We report a 6-year-old boy who presented with a medulloblastoma demonstrating classic, myoblastic, neuronal, glial, and melanotic differentiation and manifesting as severe morning headache. Magnetic resonance imaging revealed a mass lesion with cystic components in the cerebellar vermis. He underwent suboccipital craniotomy and total resection of the tumor. The specimen consisted of three morphologically distinct components. The first component consisted of densely packed cells with round-to-oval highly hyperchromatic nuclei surrounded by scanty cytoplasm. Immunohistochemical staining revealed diffuse expression of neurofilament protein and focal expression of desmin and myoglobin. The second component consisted of long spindle-shaped cells with elongated nuclei and eosinophilic cytoplasm. Immunohistochemical staining revealed diffuse expression of neurofilament protein, desmin, and myoglobin. The third component consisted of cells with small, densely hyperchromatic nuclei and scanty cytoplasm in a fine fibrillary background. Mature ganglion cells and melanotic tumor cells were also observed. Immunohistochemical staining revealed diffuse expression of synaptophysin and neurofilament protein, and focal expression of glial fibrillary acidic protein, S-100 protein, desmin, and myoglobin. The diagnosis was medulloblastoma with myoblastic, neuronal, astrocytic, and melanotic differentiation. Medulloblastoma demonstrating multipotent differentiation is rare, but the features observed in this case support the idea that medulloblastoma originates from multipotent stem cells.

Rosette-forming glioneuronal tumor of the fourth ventricle. Two cases report and literature review. / Tumor glioneuronal formador de rosetas del IV ventrículo. Presentación de 2casos y revisión de la literatura.

Rosette-forming glioneuronal tumor of the fourth ventricle is a primary central nervous system tumor introduced in the group of glioneuronal tumors in the WHO classification of 2007. Initially it was described around the fourth ventricle, but recently have been published cases in different locations. We present 2cases of this rare tumor, both surgically treated. The first in a 41 year old man with typical symptoms of posterior fossa injury. The second in an 18 year old woman, with incidental finding of posterior fossa injury that was also surgically treated. We present pre- and post-surgical magnetic resonance images, histological pictures of this tumor and we make a review of the literature.

Chordoid Glioma of Third Ventricle With an Epidermoid Cyst: Coexistence or Common Histogenesis?

Chordoid glioma (CG) is a World Health Organization classified grade II tumor located exclusively in the region of anterior third ventricle. Association of CG with other lesions is extremely rare. We report a case of CG in a 45-year-old male coexisting with an epidermoid cyst in the third ventricle. Ultrastructural examination of the CG revealed microvilli, junctional complexes, and intermediate filaments within the cytoplasm suggesting origin from specialized ependyma. The association of the 2 lesions appears coincidental as convincing evidence for a common histogenesis was not found.

Woman aged 24 years with fourth ventricular mass.

April 2005. A woman aged 24 years presented with symptoms related to a tumor in the fourth ventricle. Cytologically, the tumor was biphasic with areas typical of a classic ependymoma, including rosettes, and other areas containing grossly atypical giant cells. Many tumor cells were GFAP-positive and ultrastructural examination revealed microvilli and cilia. The histopathologic abnormalities place this tumor among the ependymomas. Its focal giant cell phenotype is very rare, but has been reported in 4 intracranial or filum ependymomas.

Central neurocytoma: report of two cases.

INTRODUCTION: Central neurocytomas are rare neuroectodermal tumors believed to arise from the subependymal matrix of the lateral ventricles. CASE REPORTS: A 26-year-old woman and a 33-year-old man each had a large, heterogeneous, contrast enhancing mass in the lateral ventricles at the foramen of Monro causing bilateral hydrocephalus. The woman died after surgery, but the man is asymptomatic after three years. HISTOPATHOLOGY: Both tumors were composed of isomorphic rounded cells positive for synaptophysin, chromogranin and NSE, while some reacted for GFAP, vimentin and S-100 protein. Electron microscopy revealed neuropil-like tissue between cells, but synapses were rare.

Subependymal giant cell tumor of tuberose sclerosis. A light and ultrastructural study.

In a small number of cases of tuberose sclerosis, tumors develop in the cerebral subependymal region. Their exact nature has been the subject of debate. The cytology, histology and electron microscopy of a tumor which developed in a 16 year old male suffering from tuberose sclerosis are presented and the findings are discussed.

A pigmented choroid plexus carcinoma: histochemical and ultrastructural studies.

A large tumor of the left lateral ventricle in a 3 1/2 year old male was diagnostic of malignant choroid plexus papilloma (choroid plexus carcinoma) as observed histologically. Focal neoplastic epithelial cells contained yellow-brown pigment which was not entirely compatible with melanin by histochemical techniques. Ultrastructurally, the tumor had definite evidence of choroid plexus origin. The neoplastic cells contained electron-dense and lamellar bodies, as well as structures of intermediate type. Premelanosomes were not observed. Thus there was no evidence for neural crest melanin. It is suggested that the pigment is probably lipofuscin and melanin derived from lipofuscin by "melanization" through pseudoperoxidation.

Cytoskeletal immunohistochemistry of central neurocytomas.

Central neurocytomas are rare intraventricular tumors. Patients with such tumors have a favorable prognosis after surgical removal. These tumors may be misdiagnosed as neuroblastomas or gliomas, risking the complications of adjuvant therapy. Diagnosis of central neurocytoma requires that the tumor shows the ultrastructural features of mature neuronal differentiation, including the presence of synapses and dense-core and clear vesicles in addition to profiles of neuritic processes with microtubules. The cytoskeletal phenotype of central neurocytomas has not been previously characterized, but it may facilitate their definitive recognition when ultrastructural examination is not possible. Ten central neurocytomas were examined by immunohistochemistry for phosphorylation-dependent/independent neurofilament epitopes, neuron-associated class III beta-tubulin, microtubule-associated proteins (MAP2, tau), and glial fibrillary acidic protein (GFAP). The neuronal nature of all neoplasms was documented by immunoreactivity for synaptophysin in nine tumors and for phosphorylation-independent neurofilament-H/M in the remaining case. Electron microscopy in four cases showed synapses and dense core vesicles. All tumors were immunoreactive for class III beta-tubulin and MAP2, which were seen in cytoskeletal structures by immunoelectron microscopy. Two thirds of the cases were immunohistochemically positive for neurofilament epitopes. None of the tumor cells displayed GFAP immunoreactivity, although reactive astrocytes were present. These data suggest that central neurocytomas may be recognized by synaptophysin immunoreactivity and that the expression of cytoskeletal epitopes indicates that these tumors are well-differentiated neuronal neoplasms.

Choroid plexus neoplasms. Clinicopathologic and immunohistochemical studies.

Choroid plexus neoplasms account for less than 1% of all intracranial tumors, with papillomas (CPPs) more frequent than carcinomas (CPCs). Immunocytochemical characterization of these neoplasms has been limited. Glial fibrillary acidic protein (GFAP), S100 protein, and keratin have been variably demonstrated by others. Ten cases were identified at two hospitals over a 25-year period; six were children and four were adults. There were seven cases of CPP and three of CPC. Extracranial metastases occurred in one case of CPC and multiple local recurrences were common. Immunohistochemical examination was performed with polyclonal antibodies to keratin, alpha-fetoprotein (AFP), desmin, neurofilament, glial fibrillary acidic protein (GFAP), neuron-specific enolase (NSE), and S100 protein, and with monoclonal antibodies to vimentin, 45- to 54-kd cytokeratin (CKER), and carcinoembryonic antigen (CEA). Among the seven cases of CPP, five were positive for CKER, three for keratin, two for CEA, two for NSE, and five for S100. Three cases of CPC were positive for CEA, three for CKER, and two for keratin. With one exception, when a neoplasm was positive for CEA and S100 it was also positive for CKER. Positivity for CEA in this group was associated with a more aggressive histologic pattern and heralded a worse prognosis. S100 immunoreactivity appeared to predominate in well-differentiated neoplasms. Keratin and CKER were found in both CPP and CPC, but may be useful in the distinction from ependymomas. Statistical analysis resulted in the following classification rule: If the CEA stain is positive and the S100 stain is negative, then the tumor is malignant; otherwise, the tumor is benign.

Central neurocytomas. Critical evaluation of a small-cell neuronal tumor.

We report herein the clinical and pathological features of 20 patients with central neurocytomas. Investigations for various differentiation antigens and cell type-specific markers were performed by immunohistochemistry using paraffin-embedded tissue. In addition, the expression of L1 adhesion molecule and of the various N.CAM (neural cell adhesion molecule) isoforms were investigated by immunoblotting studies in two frozen specimens. Central neurocytomas are clinically characterized by their intraventricular localization, occurrence in young adults, and good prognosis. It rarely occurs in patients over 50, but such cases have a poor prognosis. Total surgical excision is the best treatment. Radiotherapy is appropriate if surgery is incomplete or contraindicated. Histologically, central neurocytomas display the following features: an oligo-like pattern, usually associated with large fibrillary rosettes or perivascular arrangement, and a rich endocrine-type vasculature. Central neurocytomas have a remarkably homogeneous antigenic profile. GFAP expression is only found in scattered reactive astrocytes, S100 protein in reactive astrocytes and rare tumor cells. Among the pan-neuroendocrine markers, central neurocytomas always express neuron-specific enolase; they frequently express synaptophysin but never chromogranin A. Synaptophysin is the most reliable immunohistological marker for central neurocytomas; however, immunoreactivity could be lost with long formalin fixation. In these cases, electron microscopy is used to support the neuronal nature of the tumor cells. The expression of L1 adhesion molecule and the isoform 180 of N.CAM, indicates that central neurocytomas are formed by cells committed to neuronal phenotype. Nevertheless, advanced neuronal differentiation may be absent, as suggested by the persistence of embryonic N.CAM, the nonexpression of neurofilament proteins, and the absence of mature synapses in numerous cases. Central neurocytomas and neuroblastomas share some biochemical properties, but their respective clinicopathological features and biological behavior are dramatically different.

Differentiated cerebral neuroblastoma: a tumor in need of discovery.

A tumor with the clinical and light microscopic appearance of an oligodendroglioma that occurred in the lateral ventricles of a 25-year-old man is described. On further study this tumor proved to have the ultrastructural features typical of neuroendocrine tumors, and the presence of neuron-specific enolase was demonstrated by immunoperoxidase staining. This unusual presentation of a neuroendocrine tumor, which was entirely amitotic and free of atypia, raises important questions concerning both the true incidence of such cerebral differentiated neuroblastomas and their biologic behavior. The importance of electron microscopy and immunostaining techniques, which should be used more frequently to uncover additional cases of this tumor, is stressed.

Cerebral malignant tumors with ependymal and choroidal differentiation in two siblings.

Two siblings in a family without a history of phacomatosis or cerebral tumors developed malignant tumors in the posterior fossa at age 28 months and in the left cerebral hemisphere at age 15 months, respectively. Dual ependymal and choroid plexus epithelium differentiation was established by histological, ultrastructural, and immunocytochemical studies. The development of this rare tumor in siblings suggests an inherited predisposition, a common environmental insult, or both.

Intraventricular solitary fibrous tumor: an unusual tumor with radiological, ultrastructural, and immunohistochemical evaluation: case report.

OBJECTIVE AND IMPORTANCE: Intracranial solitary fibrous tumors have been described previously, but intraventricular solitary fibrous tumors are extremely rare. We present what is, to our knowledge, the first reported case of solitary fibrous tumor in the third ventricle. CLINICAL PRESENTATION: A 63-year-old man presented with weakness of his lower extremities and headaches. Computed tomography and magnetic resonance imaging of the brain revealed an enhancing mass in the posterior part of the third ventricle. INTERVENTION: The tumor originated from the wall of the left internal cerebral vein and extended to the posterior part of the third ventricle. Nearly total excision was performed via an infratentorial-supracerebellar approach. CONCLUSION: The differential diagnosis of intracranial solitary fibrous tumors includes fibroblastic meningioma, meningeal hemangiopericytoma, neurofibroma, and schwannoma. The differential diagnosis in the present case was greatly helped by the immunohistochemical and ultrastructural findings, along with a disease-free 3.5-year follow-up. These findings are presented with reference to previous reports.

Fourth ventricle central neurocytoma: case report.

OBJECTIVE AND IMPORTANCE: Central neurocytomas (CNs) are typically located in the lateral ventricle. Primary origins in the fourth ventricle are very rare. We discuss the clinical symptoms, imaging findings, and microscopic features of these rare tumors. CLINICAL PRESENTATION: We report a case of a fourth ventricle CN in a 35-year-old male patient with the initial symptoms of progressive headaches and blurred vision for more than 2 months. Computed tomography and magnetic resonance imaging of the brain revealed a slightly enhanced tumor in the fourth ventricle, with obstructive hydrocephalus. INTERVENTION: Total surgical removal of the tumor was performed. The tumor was initially diagnosed as an oligodendroglioma. The final definitive diagnosis as a CN was made after special immunohistochemical studies. CONCLUSION: CNs located in the fourth ventricle are extremely rare. Immunohistochemical stains and transmission electron microscopy can provide useful diagnostic information. Total tumor excision is associated with favorable prognoses. Postoperative radiotherapy may be considered for cases of subtotal excision, anaplastic histological variants, or recurrent tumors.