Cases reported "Brain Neoplasms"

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1/28. Dysembryoplastic neuroepithelial tumor (DNT): an ultrastructural study of six cases.

    We report six cases od DNT with a detailed ultrastructural characteristics. The patient age ranged from 7 to 16 years (mean 12), the location was temporal in three cases and frontal, temporooccipital and parietooccipital in each of one remaining cases. The predominant clinical feature in each case was history of episodes of intractable seizures. Histopathologically, the neoplasms were multinodular, each nodule was well-circumscribed and was composed of glioneuronal elements embedded in the variable amount of myxoid matrix. The oligodendroglial-like cells (OLC) predominated in the nodules with some accompanying mature neurons. The nodules were frequently surrounded by small calcifications which could be found also within the tumors. OLCs were immunoreactive for S-100 protein and neurons had the expression of synaptophysin and neurofilament proteins. Ultrastructurally, each tumor consisted of three major elements: neoplastic cells (OLC), elongated processes forming neuropil-like structure and expanded "mucoid" extracellular space: the latter gave an impression of cellular elements floating within it. Neoplastic cells had round, oval or elongated nuclei, no discernible nucleoli and a relatively narrow rim of the cytoplasm. Some nuclei were irregular and invaginated and pseudoinclusions were observed; a part of cytoplasm sequestered within pseudoinclusions often appeared degenerated with large blabs and electron-lucent vesicles, some of these contained in turn semicircular profiles of unknown significance. The second element consisted of innumerable cellular processes. Some of these were elongated and formed stacks connected by symmetrical symmetric or asymmetric adhesive plaque junctions. The others had shorter "neck" containing microtubules, these extended into bullous extensions. Dense-cored vesicles were occasionally observed, in both cytoplasm of neoplastic cells and within processes. In one cell, cross-sectioned annulate lamellae were found. In cytoplasm of a few cells, unusual inclusions reminiscent ribosome-lamellae complexes were observed. These were cylindrical resembling "laboratory tubes" with a cone-like endings. At higher power, walls of the "tubes" resolved into layered structures composed of several laminae; between laminae, ribosome-like structures were visible.
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2/28. ganglioglioma with a tanycytic ependymoma as the glial component.

    We studied a cystic ganglioglioma (GG) located in the right frontal lobe of the brain. Interestingly, the fibrillary spindle glial cells were often arranged in a fascicular pattern, and the generally uniform, round-to-oval delicate nuclei appeared to resemble those of ependymoma; and the neoplastic neurons often contained neurofibrillary tangles (NFTs). The glial component was positive for glial fibrillary acidic protein and occasionally contained granular or microvesicular structures positive for epithelial membrane antigen. Ultrastructural investigation revealed that the glial cells were ependymal in nature; intracytoplasmic lumina and intercellular microrosettes lined with cilia and microvilli, as well as long zonulae adherentes, were evident. In addition, chromogranin a-positive granular staining, neurosecretory-granule-like structures, and parallel arrays of microtubules were sometimes associated with the blood vessels. We considered the present case to be an unusual example of GG with an ependymoma, more precisely a tanycytic ependymoma, as the glial component; to our knowledge, the existence of ependymoma as the main glial component of this particular tumor has not been described before. The occurrence of NFTs, which has been reported in several cases of GG, was an additional, unusual feature.
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3/28. Distinctive pleomorphic xanthoastrocytoma-like tumor with exclusive abortive or aberrant neuronal differentiation and repeated recurrence--case report.

    A 9-year-old girl with a 1-month history of generalized seizure presented with a distinctive tumor resembling pleomorphic xanthoastrocytoma. Neuroimagings showed a right frontotemporal lobe tumor. Histological examination of the resected tumor indicated similarity to pleomorphic xanthoastrocytoma without staining for glial fibrillary acidic protein. The neuronal immunoreactivity and ultrastructural features showed two discrepancies: Numerous cytoplasmic processes containing rich structures suspected to be microtubules and neurofilaments were present, but neurofilament protein 70 kd/200 kd staining was negative; and many tumor cells showed synaptophysin staining, but no synaptic structures or vesicles were observed. She suffered recurrence 14 months after the first surgery. The specimen from the second operation revealed no malignant transformation with a MIB-1 labeling index of 1.9%. Only 2 months after the second operation, there was a second recurrence. Irradiation was administered (60.2 Gy). Twenty-eight months later, no tumor progression was seen. This tumor was an unconventional type with "abortive" or "aberrant" neuronal differentiation or an extreme variant of pleomorphic xanthoastrocytoma.
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4/28. Pineal parenchymal tumor with marked retinoblastic differentiation: case report.

    A 53-year-old woman was found to have a tumor in the pineal region. Histologically, Homer-Wright rosettes were sporadically distributed in a diffuse proliferation of round tumor cells that were immunoreactive for synaptophysin and chromogranin. A few perivascular pseudorosettes were also present, and the perivascular tumor cells were immunoreactive for glial fibrillary acidic protein and vimentin. By electron microscopy, well-developed junctions and pronounced interdigitation of abutting plasma membranes were noted in many tumor cells, as well as abundant intracytoplasmic microtubules. These findings indicated that the tumor was a pineal parenchymal tumor accompanied by an extraordinary epithelial-like differentiation, suggesting retinoblastic photoreceptor cell differentiation.
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5/28. Atypical extraventricular neurocytoma with oligodendroglioma-like spread and an unusual pattern of chromosome 1p and 19q loss.

    An insular cortex tumor in a 54-year-old woman showed unequivocal neurocytic features, including open nuclei, distinct nucleoli, and strong synaptophysin immunoreactivity. Ultrastructurally, there were neuritic-type processes with microtubules and hillock-like attachments, and there were dense-core granules. Atypical features were mitotic activity, prominent vasculature, and small foci of necrosis. Peripherally, there was oligodendroglia-like histology with single-cell infiltration of white matter and perineuronal spread in cortex. fluorescence in situ hybridization analysis with chromosome 1 and 19 probes showed 3 copies of 1q and 2 copies of 1p and showed 2 copies of 19q and 4 copies of 19p. This yielded a 1p-19q loss of heterozygosity pattern similar to that seen in oligodendrogliomas, although the actual chromosomal abnormality is distinct. This tumor, best classified as an atypical neurocytoma with oligodendroglia-like spread, supports suggestions of a close histogenic relationship between oligodendroglial and neurocytic tumors. This case also illustrates the limitations of relying exclusively on loss of heterozygosity analysis for tumor classification.
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6/28. Cerebral neurocytoma. A new subset of benign neuronal tumors of the cerebrum.

    Three cases of patients with unusual neuronal tumors in the cerebral hemisphere are reported. All were associated with long-standing epileptic seizures. Computed tomography disclosed low-density lesions without contrast enhancement, which were interpreted as either arachnoid cysts or a cerebral infarction at initial diagnosis. magnetic resonance imaging scans, however, revealed the lesions to be solid tumors. At surgery, the tumors were found to be relatively well demarcated, soft, and gelatinous. Histologically, all tumors were composed of small uniform stellate cells, which proliferated in a loose myxoid fibrillary matrix and resembled either oligodendroglial or astrocytic tumors. Ultrastructurally, however, all tumors showed neuronal differentiation, including numerous clear and occasional dense-core vesicles, microtubules, and a number of synapses. A review of the literature uncovered no other such cases, and therefore it was decided to classify these tumors as a distinct group of benign neuronal tumors, designated as "cerebral" neurocytoma compared with "intraventricular" neurocytoma. Related nosologic problems of neuronal tumors of the central nervous system and their possible histogenesis are also discussed.
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7/28. Pineocytoma with neuronal differentiation--case report.

    The authors describe a case of pineocytoma studied by light and electron microscopy and the immunoperoxidase method. The tumor consisted of two types of cells bearing either chromatin-rich or pale nuclei. These cells were arranged in rosettes and contained pale, eosinophilic material at the center, or in lobular patterns with thin connective tissue and a few blood vessels. Bodian silver staining disclosed a delicate tangle of argyrophilic fibers and processes with small, club-like terminations. These findings are characteristic of pineocytoma. On ultrastructural examination, the tumor cells were found to be closely packed, in clumps separated by numerous fine or expanded, interlacing processes, some of which contained microtubules. A few dense core vesicles and clusters of clear vesicles similar to synaptic vesicles were seen, the latter being aggregated around desmosome-like thickenings in the cellular membrane, suggestive of a synaptic complex. Some tumor cells were positive for neuron-specific enolase and S-100 protein. Only a few cells positive for glial fibrillary acidic protein were distributed in the tumor tissue, but it was not ascertained if they were tumor cells or normal, pre-existing astrocytes. The tumor was diagnosed as a pineocytoma with neuronal differentiation.
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8/28. Central neurocytoma--case report.

    The authors present a case of central neurocytoma in a 34-year-old female who had experienced intermittent headaches over a 10-year period. On computed tomographic (CT) scans and magnetic resonance images, the tumor appeared as a large, calcified mass occupying both lateral ventricles. A right parieto-occipital craniotomy was performed and the tumor was totally removed. While the light microscopic findings suggested a diagnosis of oligodendroglioma, electron microscopic examination demonstrated clear vesicles, microtubules, and synaptic structures within the abundant cytoplasmic processes of the tumor cells. Immunohistochemical examination showed the tumor cells to be strongly positive for neuron-specific enolase, sparsely positive for S-100 protein, and negative for glial fibrillary acidic protein. The final histological diagnosis was central neurocytoma. The postoperative course was uneventful and no further treatment was administered. She has no neurological deficits and CT has shown no evidence of recurrence during the 2 years since her surgery. Central neurocytoma is a rare tumor arising in the lateral ventricle, and the diagnosis is mainly based on electron microscopic findings. Since central neurocytoma appears to have a good prognosis following total removal alone, it is very important to distinguish between this and other ventricular tumors.
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9/28. Neuroblastic differentiation of metastases of medulloblastoma to extracranial lymph node: an ultrastructural study.

    Extracranial metastases of a poorly differentiated medulloblastoma in a 12-year-old girl were studied by thin section transmission electron microscopy and immunohistochemistry. The primary tumor did not show any differentiation as revealed by immunohistochemistry. On the contrary, the metastatic tumor cells and their processes disclosed features of neuroblastic differentiation when examined ultrastructurally: microtubules, dense core vesicles, and abortive synaptic ribbons. Several dystrophic neurites containing altered subcellular organelles were also found. Furthermore, few processes contained concentric arrays of paired membranes. This report is the first to clearly show the neuronal differentiation of extracranial metastases of poorly differentiated medulloblastoma. We speculate that metastases of medulloblastomas outside the neuraxis behave analogously to medulloblastoma explants cultured in vivo.
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10/28. ependymoma: ultrastructural studies of two cases.

    Several unusual ultrastructural findings in two ependymomas are reported. In case 1, a grade I ependymoma of the fourth ventricle, there were rosettes, perivascular pseudorosettes, and tumor cells having unusual intracytoplasmic vacuoles by light microscopy. Ultrastructurally, these vacuoles were frequently microrosettes as well as scattered, degenerated cytoplasmic processes of tumor cells. The lumina of some of the microrosettes were bordered by abnormally long and malformed zonulae adherentiae. In case 2, a recurrent grade III ependymoma of the third ventricle, there were rosettes and perivascular pseudorosettes as well as more cellular and anaplastic areas by light microscopy. Ultrastructurally, the cytoplasmic processes of tumor cells in perivascular pseudorosettes contained frequent dense-core vesicles and occasional parallel arrays of microtubules. These structures do not occur in normal mammalian ependymal cells but do occur in the ependymal tanycyte, a related cell that is plentiful in the walls of the third ventricle. Thus some of the tumor cells of this third ventricle ependymoma appear to have differentiated as tanycytes.
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