Malignant progression of an extraventricular neurocytoma arising from the VIIIth cranial nerve: A case report and literature review.

A rare case of extraventricular neurocytoma (EVN) arising from the VIIIth cranial nerve in a 34-year-old woman is reported. The patient had a 20-year history of hearing loss and facial palsy. Computed tomography showed a 3-cm enhancing lesion in the left cerebellopontine angle (CPA). At operation, the tumor was seen to originate from the cochlear and vestibular nerves. The tumor was subtotally resected. Histologically, the tumor consisted of uniform cells with oval to round nuclei and scant cytoplasm. Immunohistochemically, the tumor cells were positive for synaptophysin, but negative for glial fibrillary acid protein and S-100 protein. The Ki-67 labeling index was 0%. Twelve years after the operation, magnetic resonance imaging (MRI) showed tumor recurrence at the left CPA. The tumor was subtotally resected, and radiation therapy was given. Histologically, the tumor consisted of round cells with mild atypia and one mitosis/20 high-power fields (HPF). Immunohistochemically, tumor cells showed the same findings as the first operation sample, except for the Ki-67 labeling index (3%). Twelve years after the second operation, MRI showed a second tumor recurrence at the left CPA and surroundings of the brain stem. The tumor was subtotally resected. Histologically, the tumor consisted of anaplastic short spindle cells and five mitoses/10 HPF. The immunohistochemical findings were almost the same as the earlier operation samples. However, the Ki-67 labeling index was 20%. In addition, tumor cells from the third specimen were more strongly and more diffusely positive for GAB1 (growth factor receptor-bound protein 2-associated binding protein 1) compared to those of the earlier specimens. Electron microscopy showed the presence of numerous cell processes with a dense core and clear vesicles and microtubules. GAB1 immunostaining also indicated that malignant progression might be associated with the sonic hedgehog signaling pathways. To the best of our knowledge, this is the first report of an EVN arising from the VIIIth cranial nerve with malignant progression.

Cerebellar Liponeurocytoma, an Unusual Tumor of the Central Nervous System--Ultrastructural Examination.

Cerebellar liponeurocytoma is a rare tumor of the central nervous system which shows neuronal and variable astrocytic differentiation, along with foci of lipomatous differentiation. It is usually located in the cerebellum, and may be mistaken for medulloblastoma with lipidized cells or lipomatous ependymoma. Histopathological examination, supplemented by immunohistochemistry and electron microscopy, is required to distinguish between these entities. This 35-year-old male presented with vomiting and headache for three months, followed by gait imbalance. Neurological examination showed positive cerebellar signs with ataxic gait. Magnetic resonance imaging showed a lesion measuring 4.4 cm× 4.3 cm× 3.9 cm involving the cerebellum. The patient underwent midline suboccipital craniotomy to excise the tumor. Histopathological examination showed a circumscribed, cellular tumor composed of round to polygonal cells with moderate cytoplasm and minimal pleomorphism. Clear intracytoplasmic vacuoles were seen within the tumor cells. These tumor cells were immunopositive for synaptophysin, NSE, and MAP-2, confirming their neurocytic origin. On ultrastructural examination, lipid vacuoles as well as dense-core neurosecretory granules were identified within these neurocytic cells, confirming the diagnosis of liponeurocytoma. No cilia, microvilli, or gap junctions were identified in the tumor cells, ruling out the possibility of lipomatous ependymoma. The differentiation of liponeurocytoma from its morphological mimics is imperative, as their treatment differs drastically. The role of electron microscopy is extremely important in this differential diagnosis.

Clinicopathologic features of intracranial central neurocytomas in 2 dogs.

BACKGROUND: In humans, central neurocytomas are rare and typically benign intracranial tumors found within the lateral ventricles, although extraventricular variants have been reported. Intracranial central neurocytomas have not been previously recognized in domestic animals. OBJECTIVES: To describe the clinicopathologic features of canine intracranial central neurocytomas. ANIMALS: Two dogs with spontaneous intracranial and intraventricular neoplasms. RESULTS: Both dogs experienced seizures, rapid neurological deterioration, and death from tumor-associated complications within 5 days of the onset of clinical signs, and had neoplastic masses within the lateral ventricles. A brain MRI was performed in 1 dog, which revealed a T1-isointense, heterogeneously T2 and FLAIR hyperintense, and markedly and heterogeneously contrast-enhancing mass lesions within both lateral ventricles. Histologically, the neoplasms resembled oligodendrogliomas. The diagnosis of central neurocytoma was supported by documenting expression of multiple neuronal markers, including neuron-specific enolase, synaptophysin, neural-cell adhesion molecule, and neuronal nuclear antigen within the tumors, and ultrastructural evidence of neuronal differentiation of neoplastic cells. CONCLUSIONS AND CLINICAL IMPORTANCE: Central neurocytoma should be a differential diagnosis for dogs with intraventricular brain masses. Morphologic differentiation of central neurocytoma from other intraventricular neoplasms, such as ependymoma or oligdendroglioma, can be difficult, and definitive diagnosis often requires immunohistochemical or ultrastructural confirmation of the neural origin of the neoplasm.

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.

Central neurocytoma: report of two cases

INTRODUÇÃO: Neurocitoma central é um tumor neuroectodérmico raro, geralmente localizado nos ventrículos laterais. RELATO DE CASOS: Uma mulher de 26 anos e um homem de 33 anos apresentaram-se com hipertensão intracraniana. Exames de imagem revelaram tumor intraventricular heterogêneo, que impregnava por contraste, ocupando os ventrículos laterais e causando hidrocefalia. A mulher faleceu no pós-operatório e o homem está livre de recidiva após três anos. HISTOPATOLOGIA: Ambos os tumores eram sólidos, com células arredondadas, lembrando oligodendroglia, positivas para sinaptofisina, cromogranina e NSE e algumas para GFAP, vimentina e proteína S-100. Microscopia eletrônica mostrou neurópilo entre os corpos celulares, mas sinapses eram raras.

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.

Central neurocytoma expressing characteristics of ependymal differentiation: electron microscopic findings of two cases.

We describe two cases of central neurocytoma in the lateral ventricle. Ultrastructural examination showed occasional cilia mixed in with sparse dense core vesicles and thin tumor cell processes containing parallel microtubules. These central neurocytomas revealed evidence of ependymal differentiation. We propose that central neurocytoma originates from multiple differentiation from the germinal matrix cell layer.

Cerebellar central liponeurocytoma.

Cerebellar liponeurocytoma is a rare, benign neuroepithelial tumor that occurs exclusively in the cerebellum of adults. Its salient histological features include advanced neuronal/neurocytic differentiation, focal vacuolated cells resembling mature adipose cells, low mitotic activity, and lack of endothelial proliferation and/or necrosis. The morphological appearance of this neoplasm can be confused with that of oligodendroglioma, neurocytoma, ependymoma, medulloblastoma, hemangioblastoma, metastatic renal cell carcinoma, and other clear cell carcinomas. Its full biological potential and histological features, however, have not been fully exploited due to the rarity of this tumor. The authors describe a case with clinical, imaging, histological, immunohistochemical, and ultrastructural features.

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.

Cerebellar liponeurocytoma: immunohistochemical and ultrastructural study of a case.

The clinical, histopathological, and ultrastructural features of a cerebellar liponeurocytoma are reported. The tumor, a 3-cm mass localized in the right cerebellar hemisphere, was resected from a 61-year-old man clinically presenting with symptoms of intracranial hypertension. The lesion was composed of small, in some areas closely packed, medulloblastoma-like cells with prominent areas of lipidization phenomena. Moreover, mitoses, cellular atypia, and numerous vascular structures were focally observed. Glial and neuronal differentiation was immunohistochemically noted (glial fibrillary acidic protein, synaptophysin, neurofilaments, and neuron-specific enolase positivity). The p53 oncoprotein was detected in the majority of neoplastic cells and a moderate proliferation activity, evaluated by Mib-1 antibody, was focally appreciated. Ultrastructural study did not show evident neuritic processes, synapses, or dense core neuroendocrine granules. This cerebellar tumor previously called lipidized medulloblastoma and recently renamed cerebellar liponeurocytoma is considered an adult neoplasm with excellent prognosis histologically presenting prominent lipidized areas and, at the immunohistochemical and ultrastructural level, both glial and neuronal differentiation. The present study provides the first description of a less differentiated and histologically more aggressive form of this unusual tumor.

The biochemical analysis of neurotransmitters in central neurocytomas.

Central neurocytomas are rare benign intraventricular tumours composed of small round synaptophysin-positive cells, suggesting a neuronal origin of these tumour cells. Although past electron microscopic studies demonstrated synaptic vesicles in the synapse of central neurocytomas, the kinds of neurotransmitters in central neurocytomas have never been identified. In this study we analyzed neurotransmitters in an attempt to clarify the tumorigenesis of central neurocytomas. We studied frozen central neurocytoma specimens from four patients. The tissue levels of glutamate and GABA (gamma-aminobutyric acid) in the tumours were determined by gas chromatography-mass spectrometry (GC-MS) using a selected ion monitoring method. The tissue levels of acetylcholine, choline, catecholamines and metabolites of catecholamines in the tumours were measured by high-performance liquid chromatography combined with electrochemical detection. Choline was found in extremely high concentration in all central neurocytomas when compared with levels in controls. In one central neurocytoma, GABA was found in extremely high concentration compared with controls. In all central neurocytomas, glutamate was found in lower or identical concentrations compared with controls. In all central neurocytomas and controls, dopamine and catecholamine concentrations were extremely low. These results indicated that the histogenesis of central neurocytomas begins with the subependymal stem cells, which have the potential to differentiate into cholinergic or GABA neurons.

Intraventricular neurocytoma with prominent myelin figures.

A case is reported of intraventricular neurocytoma that had characteristic light microscopic findings of neurocytoma with prominent intracytoplasmic concentric lamellar structures mimicking myelin sheaths. On routine H&E-stained sections, this tumor showed intracytoplasmic vesicular bleb-like structures having eosinophilic cores that were consistent with ultrastructural concentric lamellar structures. Immunohistochemically, this tumor was immunoreactive for synaptophysin and neurofilament, but negative for antibody to glial fibriallary acidic protein. Electron microscopic findings fulfilled the criteria for neurocytoma, with the presence of neurosecretory granules and neurotubules. These findings may suggest dual differentiation of this tumor into neurocytes and oligodendrocytes.

Ultrastructural characterization of central neurocytomas using collagen gel culture.

Central neurocytoma is a rare brain tumor with neuronal differentiation. Cultured central neurocytoma cells are poorly described because of the tumor's scarcity. Two central neurocytomas were cultured using a monolayer culture for first few passages, and then a portion of each specimen was cultured in a collagen gel. Immunostaining for synaptophysin or glial fibrillary acidic protein performed on the primary culture revealed the presence of cells expressing synaptophysin and cells expressing glial fibrillary acidic protein. Cells expressing synaptophysin tended to disappear in passage 2, whereas the cells expressing glial fibrillary acidic protein remained. Ultrastructurally, samples in passage 5 obtained from the collagen gel cultures revealed neuron-like cells with prominent nucleoli, cell processes containing dense core vesicles and clear vesicles, and synapse-like structures. By contrast, samples obtained from passage 5 of monolayer cultures failed to reveal ultrastructural neuronal characteristics. These results suggest that spatial cell growth and the presence of collagen, i.e., extracellular matrix, may be necessary to retain neuronal differentiation in a central neurocytoma.

[Central neurocytoma]. / Neurocitoma central.

INTRODUCTION: A central neurocytoma (CN) is a rare tumor, of neuronal origin, well-differentiated and found intraventricularly. It mainly affects young adults. Firm diagnosis is made on immunohistochemical (IHQ) and ultrastructural studies, since on optic microscopy it is similar in appearance to an oligodendroglioma or to an ependymoma. PATIENTS AND METHODS: We studied 4 cases, three after surgical resection and one on autopsy. The average age was 29, ranging from 3 to 63. Both sexes were equally affected. In all cases IHQ techniques were used (GFAP, neurofilament, synaptophysin and specific neuronal enolase) and they were studied by electron microscopy. RESULTS: IHQ was negative for GFAP and neurofilament, but intensely positive for synaptophysin and specific neuronal enolase. On ultrastructural study there were few neurofilaments, microtubules and dense central granules typical of neural differentiation. CONCLUSIONS: The findings in our cases lead to diagnosis of NC and confirm that this tumor is a distinct clinicopathological entity.

Neurocytoma/rhabdomyoma (myoneurocytoma) of the cerebellum.

An unusual case of cerebellar neurocytoma with rhabdomyomatous differentiation in a 6-year-old boy is reported. Immunocytochemical and ultrastructural features of the tumour were studied. Abortive synapse formation, the presence of clear vesicles and synaptophysin immunoreactivity of the tumour cells indicated its intermediate neuronal differentiation, while the presence of myoblasts and myotubes and immunolabelling by desmin confirmed the rhabdomyomatous differentiation. In addition, the mesenchymal cells variably expressed neurofilament protein and glial fibrillary acidic protein, suggesting inductive interaction between the neuroectodermal and ectomesenchymal elements and persistence of the pleuripotential nature of the cells along the rhombic area of the brain stem.

Central neurocytoma: an immunohistochemical, ultrastructural and cell culture study.

To clarify the histogenesis and differentiation potential of central neurocytoma, a pathological investigation of seven tumors from three patients was conducted using immunohistochemistry and ultrastructural analysis in addition to systematic in vitro studies. Six tumors were studied immunohistochemically and five were examined ultrastructurally. All cases that were immunostained were positive for synaptophysin in nuclear-free neuropil islands. In five tumors, a few tumor cells, in addition to reactive astrocytes, were positive for glial fibrillary acidic protein (GFAP). Vimentin staining was also positive in a few tumor cells of five specimens. Neurofilament staining was always negative. All cases for which ultrastructure was examined showed various synaptic abnormalities. Cultured cells were subdivided into three distinct tumor cell types: neuronal cells which stained for neurofilament proteins with neurosecretory granules; small flat undifferentiated cells with a high nuclear-cytoplasmic ratio and scant cytoplasmic organelles; and small round or multipolar astrocytic cells with 10-nm intermediate filaments which stained for GFAP. Our tissue culture studies disclosed that cultured neurocytoma cells form a cellular mosaic similar to subependymal plate layers that are composed of mitotically active cells, neurons and glia.

Pseudopapillary neurocytoma of temporal lobe with glial differentiation.

We present a case of cerebral neurocytoma with unusual pseudopapillary pattern, which was a predominant feature in the tumor and was characterized histologically by hyalinized vascular cores surrounded by a single or multilayered small round cells. Vascular hyalinization was also evident in the linear arborizing capillary networks in the cellular mass of the tumor. Immunohistochemically, the tumor cells were strongly positive for synaptophysin and neuron-specific enolase except some cells lining the pseudopapillae, which showed immunoreactivity for glial fibrillary acidic protein, vimentin and S-100 protein. Ultrastructural examination revealed neuritic process of the tumor cells with occasional synaptic structures and neurosecretory granules. This report suggests that neurocytoma should be included in the differential diagnosis of papillary tumors in the central nervous system.

Ultrastructural characteristics of central neurocytoma in cell culture.

The study was performed to determine the ultrastructural characteristics of central neurocytoma and its features in primary cell culture. Fresh tissue from three tumors was mechanically and enzymatically dissociated into individual cells, which were cultured onto poly-L-lysine precoated Aclar coverslips in the media. The tumor cells attached to the surface of the coverslips within 12 to 24 h and delicate cytoplasmic processes developed within 2 to 3 days. Electron microscopic examination of the cultured tumor cells and the tumor tissue supported neuronal origin. Combined tissue culture and electron microscopic study provides a rapid, reliable, and reproducible means for the diagnosis of central neurocytoma.