[Ultrastructural characteristics of gap junctions in human glial brain tumors]. / Ul'trastrukturnaya identifikatsiya shchelevykh kontaktov v glial'nykh opukholyakh golovnogo mozga cheloveka.

AIM: to conduct an electron microscopic study of intercellular communication in the samples of gemistocytic astrocytoma, oligodendroglioma, and glioblastoma. MATERIAL AND METHODS: Surgically resected tumor tissue fragments were fixed in 2.5% glutaraldehyde solution, afterfixed in 1% OsO4 solution, dehydrated, and embedded in epoxy resin. Ultrathin sections were examined using a Jem 1011 electron microscope (Jeol, Japan). RESULTS: Solitary and closely spaced gap junctions (GJs) formed by the thin processes that have the ultrastructure of an astroglial processes were identified in the astrocytoma samples. In this case, chemical synapses were noted to be completely absent in gemistocytic astrocytoma and glioblastoma. The identified GJs had a small length and deformed nexuses. The oligodendroglioma samples exhibited intact astroglial processes around the chemical synapses; however, interglial GJs were not found. CONCLUSION: The investigation showed the presence of intercellular GJs with some ultrastructural differences in the samples of low- and high-grade astroglial tumors. According to current data, astrocytomic GJs are able to create a stable self-sustaining network that promotes tumor progression and provides resistance to a therapeutic intervention. At the same time, the noticeable reduction in the number of GJs, which is most pronounced in the oligodendroglioma sample, can accelerate tumor cell migration into the surrounding parenchyma. The investigation of GJs should be, of course, continued using a group of a larger number of glial tumors to confirm the intercellular communication features revealed in this study.

Oligodendroglial cell proliferation arising in an ovarian mature cystic teratoma. Clinicopathological, inmunohistochemical, and ultrastructural study of a case that may represent an oligodendroglioma.

Ovarian mature cystic teratoma (OMCT) is an ovarian benign neoplasm with excellent prognosis presenting components of the three germinal layers. However, transformation into a malignant neoplasm is a rare event (so-called somatic transformation). In most of the cases, the malignant component expresses as epidermoid carcinoma, but occasionally central nervous system tumors occur. Some of the previously reported tumors are astrocytoma, glioblastoma, and ependymoma. Somatic transformation of OMCT into an oligodendroglioma is exceptional. We report a 19-year-old female with a left OMCT with an area of oligonedroglial cells proliferation characterized by immunohistochemical studies with positivity for GFAP and S100, with a low Ki67 index (5%). Additionally, electron microscopy revealed oligodendrocytes with parallel bundles of cytoplasmic intermediate filaments, confirming the oligodendroglial nature of the proliferation. The patient was treated only with left oophorectomy, and three and half years after surgery, there is no evidence of disease.

Anaplastic oligodendroglioma with ganglioglioma-like maturation.

Neuronal differentiation of oligodendroglioma has been demonstrated by immunohistochemical and ultrastructural examinations in recent studies. However, oligodendrogliomas displaying a complete neurocytic morphology or even gangliocytic differentiation are rare. We describe a case of anaplastic oligodendroglioma that was characterized by the presence of ganglion cells in a 40-year-old-male. Histologically, the tumor was mainly composed of classical oligodendroglioma cells. The most exceptional finding of this tumor was the presence of ganglion cells and intermediate-sized ganglioid cells. Immunohistochemical analysis revealed that these cells were positive for Olig2 and negative for glial fibrillary acid protein (GFAP). Synaptophysin and microtubule-associated protein 2 (MAP2) were mainly detected in the ganglion cells. Fluorescence in situ hybridization analysis (FISH) revealed the deletion of the 1p and 19q chromosome arms in both the oligodendroglioma cells and ganglion cells. The R132H mutated isocitrate dehydrogenase 1 (IDH1) protein was detected by immunohistochemistry and direct DNA sequencing. The morphological, immunohistochemical, and genetic features of the tumor suggested a diagnosis of anaplastic oligodendroglioma, and this tumor was considered to be a rare form of oligodendroglioma displaying ganglioglioma-like maturation. FISH and mutant IDH1 examinations are useful diagnostic tools for the differential diagnosis of this tumor, i.e., ganglioglioma with anaplastic oligodendroglial features.

Oligodendroglioma in an african lion (Panthera leo).

A 10-yr-old female lion (Panthera leo) presented for acute onset ataxia and weakness with a history of two seizure episodes 6 mo prior to presentation and a persistent head tilt for at least 6 mo. Gross necropsy findings included a gelatinous mass in the right cerebral hemisphere extending from the frontal to the occipital lobes. Histologically, the mass was composed of polygonal cells surrounding lakes of mucinous material. These cells had clear cytoplasm, ovoid basophilic nuclei, and inapparent cell processes. Immunoreactivity was positive for S100 and neuron-specific enolase but negative for glial fibrillary acid protein, myelin basic protein, neurofilament triplet, vimentin, and cytokeratin. All findings were consistent with an oligodendroglioma. A second neoplasm, a pulmonary adenoma, was also iidentified at necropsy.

Immunohistochemical and ultrastructural characterization of brain tumors in S100beta-v-erbB transgenic rats.

Transgenic rats expressing v-erbB (viral form of the EGF receptor) under transcriptional regulation by the S100beta promoter develop brain tumors (Ohgaki et al. J Neuropathol Experimental Neurol 65: 1111-1117, 2006). In the present study, we carried out detailed immunohistochemical and ultrastructural characterization of the brain tumors that developed in these rats. Of 49 homozygous transgenic rats between 16 and 94 weeks of age (mean, 59 weeks), 31 rats were autopsied because they showed severe neurological symptoms and/or became moribund. Among these, 30 rats had brain tumors, which were classified histologically as malignant glioma, anaplastic oligodendroglioma, and low-grade oligodendroglioma. Six transgenic rats developed two different histologic types of brain tumor, which were considered to be of multiclonal origin, because of the lack of histological transitions. All brain tumors contained neoplastic cells immunoreactive for S100 and GFAP. Diffuse immunoreactivity for Olig2 and Nkx2.2 was observed in neoplastic cells in all seven anaplastic oligodendrogliomas and in all three low-grade oligodendrogliomas analyzed, but in none of 26 malignant gliomas. Electron microscopy, carried out on four malignant gliomas and four anaplastic oligodendrogliomas, revealed the presence of intermediate filament bundles devoid of side arms, indicating glial differentiation. There was no evidence of cilia, microvilli, neurosecretory granules, synaptic structures or neurofilaments, excluding the possibility of ependymal or neuronal tumors. The present study thus provides additional evidence that the brain tumors developing in S100beta-v-erbB transgenic rats are of glial origin, with or without oligodendroglial differentiation. Reproducible development of three distinct histologic types of brain tumor in unique localizations may be explained by activation of the v-erbB transgene driven by the S100beta promoter in specific precursor cells during development of the brain. Thus, S100beta-v-erbB transgenic rats may be useful to study the histogenesis and molecular mechanisms of development of glial tumors due to disruption of the EGFR pathway.

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.

Neuronal features of oligodendrogliomas--an ultrastructural and immunohistochemical study.

AIMS: To assess neuronal differentiation in oligodendrogliomas (ODGs). METHODS AND RESULTS: An electron microscopic and immunohistochemical study of 41 consecutive cases was performed. In all cases, tumour cells with neuritic structures were identified ultrastructurally, including synapses and neurosecretory granules. For the immunohistochemical identification of synaptophysin, monoclonal antibody clones 27G12, Snp88 and SY38 and a polyclonal antibody were compared in optimized protocols on slides from a spectrum of tissues and 16 ODGs. 27G12 gave the best signal-to-noise ratio, while SY38 gave the poorest. When 27G12 was applied on all 41 ODGs, widespread immunoreactivity was obtained in 100%. Among three antibodies to chromogranin compared similarly, clone LK2H10 and a polyclonal antibody gave identical patterns of immunoreactivity, whereas clone DAK-A3 gave weaker reactions. When LK2H10 was applied on all tumours, staining was found in 12 (29%). All tumours but one stained strongly for glial fibrillary acidic protein and all for synapsin I. Fluorescence in situ hybridization analysis showed a concomitant 1p/19q deletion in 12/16 ODGs. CONCLUSIONS: Our study provides evidence for widespread neuronal differentiation in ODGs, suggesting that these tumours may be derived from progenitor cells with limited commitment. Antibody selection and protocol optimization are mandatory for reliable immunohistochemistry results.

Membrane vesicles shed by oligodendroglioma cells induce neuronal apoptosis.

In order to investigate the mechanism by which oligodendrogliomas cause neuronal damage, media conditioned by G26/24 oligodendroglioma cells, were fractionated into shed vesicles and vesicle-free supernatants, and added to primary cultures of rat fetal cortical neurons. After one night treatment with vesicles, a reproducible, dose-dependent, inhibitory effect on neurite outgrowth was already induced and, after 48-72 h of incubation, neuronal apoptosis was evident. Vesicle-free supernatants and vesicles shed by NIH-3T3 cells had no inhibitory effects on neurons. Western blot analyses showed that treated neurons expressed a decreased amount of neurofilament (NF), growth-associated protein (GAP-43) and microtubule-associated protein (MAP-2). Moreover procaspase-3 and -8 were activated while Bcl-2 expression was reduced. Vesicles were found positive for the proapoptotic molecule, Fas-ligand (Fas-L), and for the B isoform of Nogo protein, a myelin component with inhibitory effects on neurons. Nogo B involvement in the vesicle effects was analyzed both by testing the neutralizing capability of anti-Nogo antibodies and by removing the Nogo receptor from neurons by phospholipase C digestion. These treatments did not revert the vesicle effects. To test the role of Fas-L, vesicles were treated with functional anti-Fas-L monoclonals. Vesicle inhibitory and proapoptotic effects were reduced. Vesicles shed by ovarian carcinoma cells (OvCa), which are known to vehicle biologically active Fas-L, had similar effects on neurons to those of oligodendroglioma vesicles, and their inhibitory effects were also reduced by anti Fas-L antibodies. We therefore conclude that vesicles shed by G26/24 cells induce neuronal apoptosis at least partially by a Fas-L mediated mechanism.

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.

Biological characteristics of cultured cells derived from various types of human brain tumors.

We placed in culture brain tumors from 45 cases (7 cases of astrocytoma, 2 from oligodendrogliomas, 2 glioblastomas, 2 ependymomas, 13 meningiomas, 6 pituitary adenomas, 5 neurinomas, a malignant lymphoma, a choroid plexus papilloma, and 6 metastatic tumors) and succeeded in making a primary culture from 33, and maintained 17 in vitro over a considerable period of time (greater than three months). In the early period of the primary cultures, the astrocytoma cells had cytoplasmic processes which contacted each other, the oligodendroglioma cells were small and spindle-shaped, the glioblastoma cells were neoplastic with pleopmorphic features and possessed cytoplasmic processes, the ependymoma cells formed a rosette-like cell arrangement, the meningioma cells were spindle- or round-shaped cells and characterized as forming psammoma bodies, the pituitary adenoma cells were round- or oval-shaped cells and produced growth hormone (GH), adenocorticoid tropic hormone (ACTH), prolactin, or other hypophyseal hormones, the choroid plexus papilloma cells were round-or polygonal and showed a papillary cell arrangement, the neurinoma cells were spindle- or fibrous-shaped cells, and the malignant lymphoma cells were round and formed cell aggregates floating in the culture medium.

Immunohistochemical analysis of p18INK4C and p14ARF protein expression in 117 oligodendrogliomas: correlation with tumor grade and clinical outcome.

OBJECTIVE: To investigate immunoexpression of 2 cyclin-dependent kinase inhibitors, p18INK4C (p18) and p14ARF (p14), in oligodendrogliomas and to evaluate the possible association with tumor grade and clinical outcome. DESIGN: One hundred seventeen specially selected cases of cerebral oligodendrogliomas were studied retrospectively. Tumor specimens were immunohistochemically examined with antibodies to p18INK4C (118.2) and p14ARF (FL-132) proteins. A computerized color image analyzer was used to count immunostained nuclei. RESULTS: p18 nuclear immunoexpression was found in 57 (49%) of the oligodendrogliomas we studied. p18 immunoreactivity exhibited a clear tendency to elevate with increasing tumor grade, and the mean p18 labeling index was 9.7% for low-grade (World Health Organization [WHO] grade II) and 19.2% for high-grade (WHO III) tumors. p14-immunopositive nuclei were found in 87 (74%) tumors, and p14 immunoreactivity showed no correlation with oligodendroglioma histological malignancy. Survival times were significantly reduced for p18-positive tumors, and risk of death was independently associated with p18 expression (hazard ratio = 2.48; P =.01). There was no difference in survival times in patients with or without p14 immunoreactivity. CONCLUSIONS: p18 protein expression is closely associated with malignant oligodendrogliomas and worse clinical outcome. It seems unlikely that p14 immunohistochemistry will be of value in assessing individual prognosis for these tumors.

Phenotypic characteristics of GFAP-positive oligodendroglial tumours. Part II: ultrastructural study.

Five cases of anaplastic oligodendrogliomas containing numerous GFAP-positive cells have been analysed by electron microscopy to establish the fine structural characteristics of neoplastic cells. Ultrastructurally, all tumours have revealed monotonous appearance typical of oligodendrogliomas, however some structural variability, particularly with reference to astrocytic differentiation, has been observed. The majority of neoplastic cells have shown the fine structural features of oligodendrocytes, accompanied by various numbers of intermediate cytoplasmic filaments. These filaments have been usually distributed in the perinuclear, less often in the peripheral, parts of the cytoplasm. The cells exhibiting features common to both oligodendroglial and astroglial cells might be regarded as an intermediate morphological form between these two cell types. True neoplastic astrocytes could be encountered only sporadically. The present electron microscopic studysupports the opinion that GFAP-positive oligodendroglial tumours contain heterogeneous neoplastic cell populations with the transitional cell types between oligodendroglial and astroglial lineage.

Oligodendroglioma: HMB-45 positivity using catalyzed signal amplification method: an immunohistochemical (HMB-45, CD31, p53, Mib-1) and ultrastructural study.

Although melanin synthesis and the presence of melanosomes are exceptionally reported in nervous system tumors, there is no record of melanotic oligodendrogliomas in the literature. The purpose of the current study was to evaluate whether melanosomes are immunohistochemically and ultrastructurally detectable in nonmelanotic oligodendrogliomas and to verify whether these data are related to prognosis. Thirty surgical specimens (19 primary lesions and 11 recurrences) from 19 patients were examined. Median survival was 80 months. Immunohistochemical studies were performed using the monoclonal antibodies HMB-45, CD31. Mib-1, and p53. Using catalyzed signal amplification (CSA), HMB-45 positivity was noticed in 3 (10%) of the oligodendrogliomas being studied. No correlation with survival was found. Ultrastructural examination displayed the presence of melanosomelike structures. Tumor vascularization, estimated by means of CD31 antibody, was increased in 6 of 19 primary lesions but there was no significant correlation with survival. Nine of the19 primary lesions were p53 negative. In these cases, survival was longer than in p53-positive tumors (P = 0.0213). Proliferation rate, evaluated with Mib-1, was unrelated to survival, but proved greater in recurrences (10 of 11 cases) than in primary tumors (7 of 19 lesions; P = 0.007).

Oligodendroglioma with signet-ring cell morphology: a case report with an immunohistochemical and ultrastructural study.

A case of oligodendroglioma with signet-ring cell (SRC) morphology arising in the right thalamic region in a 12-year-old boy is described. Histopathologically, the tumor was a composite neoplasm consisting of typical oligodendroglioma and anaplastic components with aggregates of SRC. Immunohistochemically the SRC were negative for glial fibrillary acidic protein (GFAP) but surrounded by GFAP-positive anaplastic cells with high-grade nuclear features. Typical oligodendrogliomatous components were negative for GFAP. The Ki-67 labeling index evaluated with MIB-1 antibody was 1.3% in the SRC component, 9.2% in the GFAP-positive anaplastic cell component, and 0.8% in the typical oligodendrogliomatous component. Ultrastructurally, the cytoplasm of the SRC was filled with irregularly and widely dilated cisternae of rough endoplasmic reticulum containing granular material. Intermediate filaments and a small number of other organelles were distributed in the perinuclear and peripheral areas. Both the SRC and anaplastic cells had slender cytoplasmic processes, although those of the SRC were short and few in number. These findings are distinct from those of SRC hitherto described in oligodendrogliomas to date, and suggest that there is a morphological heterogeneity in SRC rarely seen in oligodendrogliomas and that some examples of SRC are related to the anaplastic cells with astrocytic features in their origin.

Oligodendroglioma with granular cells: a case report.

Oligodendrogliomas can display a spectrum of histologic and ultrastructural features. The authors describe a case of an oligodendroglioma composed almost exclusively of eosinophilic granular cells. By electron microscopy, the tumor cells had abundant lysosomes containing electron-dense pleomorphic material. Although eosinophilic granular cells can be seen focally in oligodendrogliomas, it is unusual for them to pre-dominate. By light microscopy alone, such an appearance raises a broad differential diagnosis that electron microscopy can help resolve. In addition, the ultrastructural similarities between this tumor and granular cell tumors in general support the idea that granular cell neoplasms are a phenotype expressed by a wide variety of cells.

Oligodendrogliomas. Part I: Patterns of growth, histological diagnosis, clinical and imaging correlations: a study of 153 cases.

The present study has attempted to demonstrate that the morphological spectrum of oligodendrogliomas includes tumors which are traditionally misinterpreted as 'diffuse fibrillary astrocytoma'. We have shown that these tumors are in fact made of isolated neoplastic oligodendrocytes which are entrapped in a fibrillary background composed of axons and fibrillary reactive gliosis. Analysis in a series of 153 'pure' supratentorial oligodendrogliomas composed of 'classical' or pseudo 'diffuse fibrillary oligodendrogliomas' diagnosed by imaging-based serial stereotactic biopsies showed that 2/3 of the tumors were exclusively made of isolated tumor cells (ITCs) (structure type III) and that only 1/3 of them exhibited both ITCs and solid tumor tissue components (structure type II). The tumor tissue destroys the brain parenchyma and contains new formed microblood vessels whereas ITCs do not destroy the parenchyma and are not associated with microangiogenesis. These fundamentally opposite morphological characteristics were reflected by the following findings: 1) contrast enhancement was observed in 64% of structure type II but was never seen in structure type III oligodendrogliomas. 2) a neurological deficit occurred in 57% of structure type II but in only 8% of structure type III oligodendrogliomas. 3) using the new grading system described in the companion paper to this study, we found that the biological behavior of oligodendrogliomas was also closely related to the patterns of tumor growth. From a synthesis of data gathered in this study it is suggested that emergence of microangiogenesis within a tumor which at first grows slowly with a structure type III pattern is a crucial event toward more aggressive behavior.

Signet-ring cell oligodendroglioma--report of two cases and discussion of the differential diagnosis.

Two cases of oligodendroglioma consisting largely of signet-ring cells were analyzed histopathologically, immunohistochemically and at the ultrastructural level. The signet-ring cells were negative for a panel of tumor lineage markers including glial fibrillary acidic protein, and were negative for Ki-67 (MIB-1 immunohistochemistry). In contrast with the abundance of lysosomal structures reportedly present in the so-called eosinophilic granular cells in oligodendrogliomas, degenerating mitochondria were mainly seen in the cytoplasm of the signet-ring cells. The differential diagnosis of the oligodendroglial signet-ring cell tumors occurring in children and in adults is discussed.

[Observation on oligodendroglioma with light, electron microscopy and immunohistochemistry].

OBJECTIVE: To investigate the ultrastructural and histological characteristics of oligodendroglioma (ODG). METHODS: By means of light microscopy and partially electron microscopy and immunohistochemistry, 65 cases of ODG were observed. RESULTS: According to WHO classification of the tumor, all 65 cases of ODG were graded in the degree of differentiation of tumor cells, showing 19 cases of Grade I, 32 cases of Grade II and 14 cases of Grade III. CONCLUSIONS: (1) The presence of glial filaments in tumor cells may be explained as a heterogeneity in differentiation. (2) Besides the degree of differentiation, some other criteria such as cellular density and mitotic activity are also closely related to the grading of ODG.