Intramedullary gangliogliomas: histopathologic and molecular features of 25 cases

Gangliogliomas are uncommon glioneuronal tumors, which usually arise in the cerebral hemispheres and occasionally in the brain stem. Gangliogliomas occurring in the spinal cord are extremely rare. In this study, we analyzed the clinical, histopathologic, and molecular features of 25 spinal gangliogliomas. The cases included in our series affected mostly children and young adults (15 males and 10 females; mean age, 20 years; median age, 14 years; age range, 1-72 years) and were predominantly localized in the cervical and thoracic spine. From the clinical point of view (detailed follow-up available for 9 pediatric cases; mean follow-up: 2 years 10 months; range, 3 months to 5 years 10 months), most patients showed stable disease after subtotal resection. Radiotherapy was rarely used as adjuvant treatment. Histologically, gangliogliomas (WHO grade I) (21 cases) showed features largely similar to their supratentorial counterparts. Anaplastic gangliogliomas (World Health Organization grade III) (4 cases) showed features of anaplasia (including high cellularity and increased mitotic and proliferation activity). From a molecular point of view, only 2 tumors (2/19, 11%) harbored a BRAF(V600E) mutation. In conclusion, although spinal gangliogliomas display histologic and clinical features similar to their supratentorial counterparts, they show a relatively low frequency of BRAF(V600E) mutations, alteration otherwise common in hemispheric and brain stem gangliogliomas.

Glioneuronal Tumor With Neuropil-like Islands (GTNI): A Report of 8 Cases With Chromosome 1p/19q Deletion Analysis

Glioneuronal tumor with neuropil-like islands (GTNI) is a rare neoplasm harboring circumscribed loci of neuronal differentiation and diffusely infiltrating astroglial and oligodendrocytelike components. We report 8 previously unpublished examples of GTNI, specifically studied for chromosome 1p and 19q allelic losses. All tumors showed characteristic histologic features and immunoprofile. One primary tumor displayed frankly malignant histology with frequent mitoses, microvascular proliferation, and necrosis. This tumor progressed within months of the initial resection. Three other tumors (2 low-grade and 1 showing only focal microvascular proliferation) recurred at 2 years, 3 years, and 1 year, respectively. All cases were evaluated for 1p/19q allelic losses by standard polymerase chain reaction-based loss of heterozygosity assays. No evidence of 1p/19q losses was found in 7 of 8 tumors. One tumor demonstrated small interstitial deletions at 1p36 (at D1S1612 and D1S513, but not at D1S548 or D1S1592) and a small interstitial deletion at 19q13 (at D19S219 and D19S412, but not at PLA2G4C). The lack of large, whole-arm 1p/19q losses (such as those found in oligodendroglial tumors), aberrant p53 expression, and the predominance of astroglial components may indicate a biologic relationship of the GTNI to diffuse astrocytoma. Although GTNI shares some morphologic features with recently reported cases of oligodendroglioma with neurocytic differentiation, the 2 tumors appear different at the molecular genetic level.

Glioneuronal phenotype in a diencephalic pilomyxoid astrocytoma

We report the presence of divergent populations of cells in a hypothalamic/chiasmatic pilomyxoid astrocytoma of an 11-month-old male, exhibiting differential immunohistochemical localizations for glial fibrillary acidic protein (GFAP) and synaptophysin. The tumor cells were negative for Neu-N and neurofilament protein. Ultrastructurally, the tumor comprised 2 cell types, one with features attributable to a neuronal phenotype alongside cells exhibiting an overt astroglial phenotype. This composite organization was confirmed by confocal microscopy, which revealed 2 distinct, albeit tightly interwoven, populations of GFAP and synaptophysin-labeled tumor cells. Our results indicate that a subset of the so-called pilomyxoid astrocytomas of the hypothalamic/chiasmatic region may represent phenotypically mixed glioneuronal neoplasms distinct from the pilocytic astrocytomas.

Desmoplastic noninfantile ganglioglioma: report of a case

Desmoplastic infantile ganglioglioma is a rare superficial supratentorial tumor that occurs within the first two years of life. Despite the worrisome radiological and histological appearance, the tumors are often curable following gross total resection. Tumors with similar characteristics are exceedingly rare in the noninfantile population. We present a six-year-old boy with seizures, weakness, and unsteady gait. Radiographic imaging confirmed a very large, solid and cystic mass in the right temporal-parietal region. Pathological examination demonstrated a tumor with severe desmoplasia identical to those reported as "desmoplastic infantile ganglioglioma." This case adds to the limited data available for desmoplastic gangliogliomas in the noninfantile population. It is not clear, yet likely, that the noninfantile form of this neoplasm is biologically similar to the infantile form. It is also unclear whether the desmoplastic noninfantile ganglioglioma has characteristics similar to classical ganglioglioma. This rare case highlights the remarkable versatility of glioneuronal tumors in children.

Desmoplastic infantile ganglioglioma with high proliferation index: report of a case

Desmoplastic infantile ganglioglioma (DIG) is an uncommon neuroepithelial tumor associated with epilepsy, mostly occurring in the first 2 years of life. Most DIGs carry good prognosis after complete resection, even when a primitive cellular element is present. However a few examples of DIG with histologic anaplasia have recently been reported, and one demonstrated an unusual aggressive behavior. The authors describe herein a DIG with high Ki-67 proliferation index (30%) in a 10-month-old male infant with epilepsy, but with an excellent prognosis after total tumor resection.

Desmoplastic infantile ganglioglioma: a potentially malignant tumor?

Desmoplastic infantile ganglioglioma is a rare intracranial tumor of early childhood with a usually excellent prognosis despite malignant features both radiologically and histologically. We present the case of a desmoplastic infantile ganglioglioma with histologically highly anaplastic features and both intracerebral and pial metastases. After partial resection the tumor was rapidly progressive and new metastases appeared. A combination of vincristine and carboplatinum was used according to the Low Grade Glioma Protocol of the International Society of Pediatric Oncology, with a temporary good response. When histologically characterized by highly anaplastic features, it seems the biologic behavior of this tumor remains uncertain. The aggressive behavior and the responsiveness to chemotherapy in this case may challenge the belief in the benign nature of these rare tumors.

A rosette-forming glioneuronal tumor of the fourth ventricle: infratentorial form of dysembryoplastic neuroepithelial tumor?

Eleven cases of a distinctive tumor of the posterior fossa are described. The patients (age range 12-59 years) presented with headache and/or ataxia. Neuroimaging revealed a relatively discrete, focally enhancing mass(es) primarily involving the aqueduct, fourth ventricle, and cerebellar vermis. Hydrocephalus was present in seven cases, and two lesions were multicentric. In two cases a significant increase in tumor size was documented. Gross total or subtotal resections were achieved in 10 cases. One patient underwent biopsy alone and another received postoperative irradiation. Histologically, two components were identified in all cases. One consisted of neurocytes forming neurocytic and/or perivascular pseudorosettes in a fibrillary, partly microcystic matrix. The second, astrocytic component resembled pilocytic astrocytoma in 10 cases and consisted of fibrillated spindle cells with oval nuclei associated with occasional Rosenthal fibers, granular bodies, glomeruloid capillaries, and microcalcifications. Regionally, this component was more diffuse and patternless, consisting of sheets of round to oval, oligodendrocyte-like cells. Rare ganglion cells were seen in four cases. The rosettes were consistently synaptophysin and MAP-2 immunoreactive, whereas the spindle cells were positive for S-100 protein and glial fibrillary acidic protein. Overall, atypia was minimal; no mitoses were found, and Ki67 labeling indices were low. Ultrastructurally, the neurocytic cells featured processes containing microtubules and occasional dense core granules. Mature synapses were found in one of the four cases studied. Although the histologic features of this unique tumor superficially resemble those of dysembryoplastic neuroepithelial tumor, rosette formation by neuronal cells, the frequent presence of a pilocytic astrocytoma component, and the growing nature of the lesion argue against that diagnosis, as does occasional multifocality.

Immunophenotype of pleomorphic xanthoastrocytoma

Pleomorphic xanthoastrocytoma (PXA) is an uncommon tumor, often seizure-associated and occurring in the temporal lobe of young adults. Although its cells are considered astrocytic in nature, recent studies suggest the presence of neuronal differentiation and a possible relationship to glioneuronal neoplasms. We immunostained 40 cases of PXA, including two composite PXA-gangliogliomas (PXA-GG), with a panel of glial (glial fibrillary acidic protein, S-100 protein) and neuronal markers (class III beta-tubulin, synaptophysin, neurofilament proteins, MAP2, and chromogranin A). Conventional PXAs demonstrated immunoreactivity for glial fibrillary acidic protein (100% of cases), S-100 protein (100%), class III beta-tubulin (73%), synaptophysin (38%), NF proteins (18 and 8%), and MAP2 (8%). Chromogranin A stain was absent in all conventional PXA cases. Neoplastic ganglion cells in both PXA-GGs stained with class III beta-tubulin, synaptophysin, and chromogranin A. Ultrastructural studies, performed in nine cases, demonstrated neuronal features including microtubules, dense core granules, and/or clear vesicles largely limited to cell processes (two PXAs) and in the cytoplasm (PXA component of one PXA-GG). Although the essential nature of PXA is clearly and uniformly glial, the significance of the limited neuronal differentiation is unclear, as it is the relationship between conventional PXA and PXA-GG. We found no evidence that the former is a precursor of the latter.

Anaplastic ganglioglioma with sarcomatous component: an immunohistochemical study and molecular analysis of p53 tumor suppressor gene

The present case report describes a case of ganglioglioma with a distinct sarcomatous component in the left temporal lobe of a 59-year-old Japanese man. Neoplastic neuroglial tissue contained both benign and anaplastic glial components with a MIB-1 labeling index of 0.1% and 12.0%, respectively. Sarcomatous tissue adjacent to the anaplastic glial tissue was dominated by pleomorphic fibroblastic cells with a MIB-1 labeling index of 10.8%. They were immunoreactive for smooth muscle actin, type IV collagen, and alpha 1 antitrypsin, but not for desmin and CD34. Interestingly, some of the sarcomatous cells were double-positive for smooth muscle actin and GFAP. The p53 protein had accumulated in the anaplastic astrocytes and sarcomatous cells, but direct DNA sequencing of PCR products failed to detect any mutation in the p53 gene (from exon 4 to exon 10).

Cytologic features of desmoplastic infantile ganglioglioma: a report of two cases

BACKGROUND

Desmoplastic infantile ganglioglioma (DIG) is a rare intracranial tumor of infancy, characterized by solid and cystic components, voluminous size and supratentorial location. Although its histologic features have been reported, there has been no cytologic description of the tumor. Cytologic findings on imprint and aspirated material from two cases of histologically verified DIG are discussed.

CASES

A 12-month-old male with cutis marmorata telangiectatica congenita and a 44-month-old female with episodes of spasm were referred to our center. Radiologic examination revealed a large, cystic, supratentorial mass in both patients. The mass was surgically removed, and histology revealed prominent desmoplasia with a mixture of astroglial and neuronal cells. Cytologic findings on imprint material and the needle aspirates taken from the cystic area of the tumor revealed a few isolated or sheetlike arrangements of small cells positive for glial fibrillary acidic protein and a few large cells with abundant cytoplasm and prominent nucleoli, positive for neuronal marker.

CONCLUSION

Although distinction between ganglioglioma and DIG may be difficult by cytology alone, with the characteristic clinical presentation and radiologic findings, the possibility of DIG should be kept in mind when the specimens contain both astroglial and neuronal elements.

Ex vivo pediatric brain tumors express Fas (CD95) and FasL (CD95L) and are resistant to apoptosis induction

Fas (APO-1/CD95/TNFRSF6) is a member of the tumor necrosis/nerve growth factor receptor family that signals apoptotic cell death in sensitive cells. Expression of Fas and its agonistic ligand (FasL/TNFSF6) was investigated in ex vivo pediatric brain tumor specimens of various histologic types. Fas expression was identified in all of the 18 tumors analyzed by flow cytometry and immunohistochemistry. FasL expression was identified in most of the 13 tumors analyzed by both Western analysis and immunohistochemistry. Nine of these tumor specimens were treated with either the agonistic anti-Fas antibody (APO-1) in combination with protein A or FasL in short-term cytotoxicity assays. Sensitivity to apoptosis induced by the topoisomerase II inhibitor, etoposide, was also assessed. Despite the presence of Fas, all the specimens analyzed demonstrated a high degree of resistance to Fas-mediated apoptosis. These 9 specimens also showed a high degree of resistance to etoposide. Only 2 of the 9 specimens were susceptible to etoposide-induced cell death, whereas only 3 were sensitive to Fas-mediated apoptosis. One brain tumor was sensitive to both Fas ligation and etoposide treatment. This contrasted with the high degree of susceptibility to both etoposide- and Fas-induced apoptosis observed in the reference Jurkat cell line. The results suggest that Fas expression may be a general feature of tumors of the CNS and that a significant degree of resistance to Fas-mediated apoptosis may exist in ex vivo pediatric brain tumor specimens.

Glioneuronal tumor with neuropil-like islands

Mixed glioneuronal neoplasms are relatively uncommon tumors in the central nervous system. Recently, an unusual glioneuronal tumor arising in adults marked histologically by neuropil-like islands was described. We present a similar case arising in a 23-year-old woman who presented with headaches and seizures and on imaging studies was noted to have a frontal-temporal lobe mass. The patient underwent partial resection of the tumor, which histologically resembled anaplastic astrocytoma, and received a course of radiation therapy and chemotherapy. Increasing seizure frequency and expanding size on neuroimaging prompted a re-excision of the tumor. The second resection was marked by islands of tissue resembling gray matter with slightly atypical neuronal and glial cells situated in the white matter. These islands stained positively with synaptophysin and did not stain with glial fibrillary acid protein. Mild vascular proliferation and moderate nuclear pleomorphism also characterized the tumor. Areas of necrosis were not noted. A MIB-1 labeling index of 18.1% was noted. P53 immunoreactivity was observed in approximately 40% of tumor cell nuclei. This lesion is felt to represent a clinically aggressive glioneuronal neoplasm with an unusual and distinctive histologic phenotype. HUM PATHOL 31:1435-1438.

Class III beta-tubulin immunoreactive intranuclear inclusions in human ependymomas and gangliogliomas

We have observed intranuclear inclusion bodies immunoreactive for the cytoskeletal protein class III beta tubulin (C3betaT) in neurons and ependymal cells of post-mortem human brain. The relationship of these inclusions, detected by light microscopy, to the intranuclear rodlets described by the classical microscopists is unknown. The present study was conducted to determine whether these proteinaceous inclusions (C3betaT-NIIs) exist in the neoplastic counterparts of these cell types. Immunohistochemical staining for C3betaT revealed intensely stained, predominantly rod-shaped intranuclear inclusions in a variable proportion of tumor cells in five of ten ependymomas. In addition, C3betaT-NIIs were encountered in less than 1% of neuronal cells in two of five gangliogliomas. This study represents the first report of tubulin-containing intranuclear inclusions in brain tumors. The functional significance of these inclusions in normal human brain and in cerebral neuroepithelial neoplasms remains to be determined.

Desmoplastic infantile ganglioglioma

We present the clinical, anatomic, and laboratory findings in a 4-month-old child with desmosplastic infantile ganglioglioma. Microtubule-associated protein-2 (AP18) and neuron-specific B-tubulin (TUJ-1) were more sensitive in detecting immature neural elements than synaptophysin. Despite the immature neuroblastic component, focal intermediate proliferation indices, microinvasion, presence of secondary features (extension into Virchow Robin spaces, perineuronal satellitosis), and subtotal resection, the child has done well, with striking improvement of the magnetic resonance imaging (MRI) image, head size improvement, no tumor recurrence, and minimal neurological deficits.

Evidence for developmental precursor lesions in epilepsy-associated glioneuronal tumors

The etiology and pathogenesis of epilepsy-associated local lesions remain largely unknown. Histopathologically, the most frequent lesions comprise gangliogliomas and glioneuronal malformations, i.e., hamartias or hamartomas, with a preferred location in the temporal lobe of young patients. A characteristic histopathological admixture of glial and neuronal elements, the focal appearance and the benign clinical behaviour suggest a malformative nature. So far, no molecular genetic alterations specifically involved in the pathogenesis of these glioneuronal lesions have been identified. However, immunohistochemical analysis revealed distinct distribution patterns of oncofetal antigens. The embryonic form of the neural cell adhesion molecule is present within glioneuronal hamartias, indicating an early migrational disorder. Recently, we have observed immunoreactivity for the stem cell marker CD34 in the majority of gangliogliomas and glioneuronal hamartomas. Based on these findings, we propose a common origin of gangliogliomas and glioneuronal hamartomas from a bipotent precursor that undergoes abnormal glioneuronal development.

Mixed dysembryoplastic neuroepithelial tumor and ganglioglioma

We report a case of a 15-year-old girl with new onset seizures, who had a mixed dysembryoplastic neuroepithelial tumor (DNT) and ganglioglioma of the right parieto-occipital lobe. The tumor appeared well demarcated and exhibited a low T1 and a high T2 signal on magnetic resonance imaging. Architecturally it was in large part intracortical and multinodular, but also featured a leptomeningeal component. The former corresponded to DNT, a proliferation of oligodendroglia-like cells (OLCs) arranged in nodules, as well as comprising a diffuse internodular element featuring "floating neurons" in a mucoid matrix. The leptomeningeal portion of the lesion was a ganglioglioma consisting of large neurons and astrocytes in association with marked desmoplasia. Spatially, the two components abutted one another but appeared distinct. Immunohistochemistry showed the neurons of the ganglioglioma to be positive for class III beta-tubulin, synaptophysin, and chromogranin A, whereas the astrocytic cells stained only for glial fibrillary acidic protein. Most OLCs in the DNT were positive for S-100 protein. This apparently mixed lesion suggests that a close histogenetic relationship exists between DNT and ganglioglioma. We postulate that the pluripotential progenitor cells residing in the subpial granular layer may have given rise to the cortical DNT and to the leptomeningeal ganglioglioma. To our knowledge, this is the first detailed histological, immunochemical and ultrastructural report of a mixed DNT and ganglioglioma.

Pleomorphic xanthoastrocytoma with gangliogliomatous component

We describe a composite glio-neuronal tumor comprising pleomorphic xanthoastrocytoma (PXA) and ganglioglioma identified in a left temporal biopsy. The 32-year-old male patient underwent surgery following a clinical history of persistent headaches of 6 years' duration. Immunohistochemical double labeling with antibodies to synaptophysin, beta-tubulin isotype III, GFAP and CD44H demonstrated neoplastic neurons and astrocytes in the ganglioglioma, while coexpression of glial and neuronal markers was found in a subset of PXA tumor cells variously showing giant cell or spindle cell morphology. There were gradual transitions between the two neoplastic populations. These findings raise the possibility of ganglioglioma having evolved by differentiation of bipotential PXA tumor cells along astrocytic and neuronal lineages. The PXA may, therefore, be closely related to desmoplastic neuroepithelial tumors of infancy, a group of neoplasms of presumed embryonal origin.

The clinical significance of extracellular matrix in gangliogliomas

Based on in vitro studies which demonstrate that collagen IV and laminin inhibit the proliferation and invasiveness of glioma cells, we investigated the clinical significance of these extracellular matrix proteins (ECM) in patients with gangliogliomas, tumors in which ECM is often a prominent feature. Our study compared the relative presence and deposition pattern of collagen IV and laminin in 19 gangliogliomas and in 18 gliomas without ganglion cell differentiation (8 low-grade astrocytomas, 7 anaplastic astrocytomas, and 3 anaplastic mixed gliomas). We also examined whether the presence of collagen IV and laminin correlated with other features often observed in gangliogliomas, including perivascular lymphocytic inflammation, granular bodies, microcalcification, and subarachnoid extension, and whether any of these features were associated with the patient's clinical course. Significant deposition of collagen IV and laminin was found in 9 gangliogliomas (47%), but in none of the other gliomas. The presence of these extracellular proteins in gangliogliomas correlated with both perivascular inflammation (P = 0.003), and involvement of the leptomeninges by tumor (P = 0.008). The duration of symptoms prior to surgical resection was significantly longer for patients whose tumors showed extracellular deposition of collagen IV and laminin than for patients whose tumors lacked deposition of these proteins (mean 13.7 vs 5.1 years; P = 0.02). In addition, the duration of symptoms was significantly longer for patients whose tumors exhibited perivascular inflammation than for patients whose tumors displayed little or no perivascular inflammation (mean 14.8 vs 4.8 years; P = 0.01). These findings suggests that collagen IV and laminin and perivascular inflammation are related to the indolent behavior of gangliogliomas.

Rapid growth of an optic nerve ganglioglioma in a patient with neurofibromatosis 1

BACKGROUND

Optic nerve gangliogliomas are extremely rate tumors of the central nervous system composed of elements of glial and neuronal origin. The clinical and biologic behavior of gangliogliomas depends on the glial component. Pilocytic gangliogliomas generally have a low growth rate and good ultimate prognosis. No definitive relation has yet been established between gangliogliomas and neurofibromatosis type 1.

METHODS

The authors describe the clinical, histologic, and immunohistochemical features of an optic nerve ganglioglioma with several atypical findings. A review of the literature is provided.

RESULTS

An optic nerve glioma was diagnosed in a 16-year-old patient who had signs of neurofibromatosis type 1; the atypical clinical course involved a rapid progression of symptoms with a significant increase in tumor size. The tumor was removed surgically and found to be a ganglioglioma composed of pilocytic glial cells (immunoperoxidase-positive for glial fibrillary acid protein) and neurons (immunoperoxidase-positive for neuron specific enolase, synaptophysin, and neurofilament). A focal astrocytic area showed increased cellularity, several mitotic figures, and an elevated labeling index with Ki-67 immunoperoxidase staining.

CONCLUSION

Optic nerve gangliogliomas are rare tumors that cannot be distinguished clinically from pilocytic astrocytomas. Although these tumors usually grow slowly, careful follow-up is advised. The atypical histologic features are considered to be a manifestation of rapid local growth rather than a harbinger of malignant behavior. The authors' findings suggest that gangliogliomas may be included in the diagnostic criteria for neurofibromatosis type 1.

Cortical architectural abnormalities and MIB1 immunoreactivity in gangliogliomas: a study of 60 patients with intracranial tumors

Gangliogliomas are generally low grade neoplasms composed of mixtures of neoplastic glial and neuronal elements whose origin and exact nature are still controversial. We studied a series of 60 intracranial gangliogliomas looking for coexistent cortical architectural abnormalities (cortical dysplasia, microdysgenesis) and to determine if tumor behavior correlates with MIB1 (marker of cellular proliferation) labeling. The patients included 34 males and 26 females who ranged in age from 6 months to 55 years (mean 20 years). Thirty-eight tumors (63%) were located in the temporal lobe and 6 (10%) in the frontal lobe. Fifty-four patients (90%) presented with seizures (most with intractable epilepsy) and the duration of seizures ranged from 1 to 38 years (mean 14 years). In all cases, the predominant glioma component resembled a low grade fibrillary astrocytoma. In 14 tumors (23%), an oligodendroglial component was present. In one case, the glial component resembled an anaplastic astrocytoma. The tumors were characterized variously by perivascular chronic inflammation (N = 45, 75%), vascular proliferation (N = 36, 60%), granular bodies (N = 54, 90%), binucleated neurons (N = 36, 60%), calcification (N = 28, 47%), and cystic degeneration (N = 26, 43%). Meningeal involvement by tumor was observed in five (8%) cases. In 38 patients, sufficient tissue was resected to evaluate for the presence of concomitant cortical architectural abnormalities. Cortical architectural abnormalities were identified near to but clearly separate from the tumor in 19 (50%) patients. Only four patients including the anaplastic tumor died with tumor progression. MIB1 indices (positive tumor cells/1,000 tumor cells counted) in 54 cases ranged from 0 to 10.2 (mean 1.1 +/- 1.0).(ABSTRACT TRUNCATED AT 250 WORDS)

Ganglioglioma of the brain stem: neurological dysfunction of 16-year duration

An autopsy case of a brain stem ganglioglioma in a 38-year-old male patient with neurological dysfunction of 16-year duration is reported. Immunohistochemical investigation of the tumor was performed using a panel of antibodies against neurofilament protein (NFP), synaptophysin (SY 38), beta-tubulin (TUJ1), neuron specific enolase (NSE), and glial fibrillary acidic protein (GFAP). The value of these markers in the establishment of the diagnosis, as well as the general features, the prognosis and the therapeutic approach of the gangliogliomas are discussed.

Cytoplasmic inclusions of astrocytic elements of glial tumors: special reference to round granulated body and eosinophilic hyaline droplets

Round granulated body (RGB) and eosinophilic hyaline droplets (EHDs) have been described as cytoplasmic inclusions of certain astrocytic tumors. In the previous literature, however, these inclusions have been described using various terms or regarded as nosologically the same entity. Light microscopically, RGB appeared as a round discrete body filled with fine uniform granules, while EHDs demonstrated a cluster of bright eosinophilic, round objects of various size. They could be clearly distinguished even by conventional histochemical staining such as the Masson trichrome stain and the phosphotungstic acid hematoxylin preparation. Both RGB and EHDs expressed positive immunoreactions for glial fibrillary acidic protein, several lysosomal markers, and some stress-response proteins. The ultrastructural appearances of these inclusions were distinct, however, one common feature was that they consisted of aggregations of numerous membrane-bound electron-dense bodies. Thus, both inclusions appear to be produced by neoplastic astrocytes and are possibly related to the lysosomal system. We examined the presence of RGB and EHDs in 138 astrocytic tumors. Both inclusions occurred most frequently in pleomorphic xanthoastrocytomas, followed by gangliogliomas and pilocytic astrocytomas. Subependymal giant cell astrocytomas exhibited only RGBs. RGBs and EHDs were not seen in any abundance in glioblastomas, gliosarcomas, fibrillary astrocytomas, protoplasmic astrocytomas, or oligo-astrocytomas. Some glioblastomas, however, showed only EHDs in small numbers. Several anaplastic astrocytomas were associated with a large number of RGBs and/or EHDs, and they revealed only rare mitosis despite marked cellular pleomorphism. Although RGB and EHDs have different morphological features, the presence of these inclusions in abundance may represent either a degenerative change, a long-standing lesion, or an indolent growth of the astrocytic tumors.

An immunohistochemical study of peripheral neuroblastoma, ganglioneuroblastoma, anaplastic ganglioglioma, schwannoma and neurofibroma in cattle

Immunohistochemical analysis of five paraffin wax-embedded neoplasms was performed to elucidate the characteristics of bovine nervous-tissue tumours. In case 1 (peripheral neuroblastoma), the neoplastic tissue was characterized by the formation of true and Homer-Wright rosettes and the existence of neuron-specific enolase. The neoplastic cells were possibly more immature than those of common neuroblastomas, because similar features are observed in human malignant neuroepitheliomas. The neoplastic cells in case 2 (ganglioneuroblastoma) ranged from large cells with abundant neurofilaments to immature small cells, rarely with neurofilaments or glial fibrillary acidic protein (GFAP). Such expression suggests the presence of pluripotential cells. The neoplastic tissue in case 3 (anaplastic ganglioglioma) was strikingly polymorphous, and had five elements; neuronal, astrocytic, oligodendrocytic, spindle cell and small oval cell. The neoplastic neurocytes and astrocytes were, respectively, characterized by neurofilament and GFAP positivity. The neoplastic oligodendrocytes made a honeycomb appearance, and the neoplastic spindle cells and small oval cells were considered to be less differentiated. The tumours of cases 2 and 3, which contained poorly differentiated cells and revealed both neuronal and glial differentiation, may be specific to calves. In case 4 (schwannoma), almost all the neoplastic cells were positive for S100 protein, while S100-negative fibroblasts were present in many areas of case 5 (neurofibroma). These two tumours were readily distinguished histologically and immunohistochemically.