An electron microscopic study of meningiomas

Alterations of oxidative phosphorylation in meningiomas and peripheral nerve sheath tumors

BACKGROUND

Changes in the mode of aerobic energy production are observed in many solid tumors, though the kinds of changes differ among tumor types. We investigated mitochondrial energy metabolism in meningiomas and peripheral nerve sheath tumors, taking into consideration the histologic heterogeneity of these tumors.

METHODS

Oxidative phosphorylation (OXPHOS) complexes and porin (a marker for mitochondrial mass) were analyzed by immunohistochemical staining of meningiomas (n = 76) and peripheral nerve sheath tumors (schwannomas: n = 10; neurofibromas: n = 4). The enzymatic activities of OXPHOS complexes and citrate synthase were determined by spectrophotometric measurement. Western blot analysis of OXPHOS complexes, porin, and mitochondrial transcription factor A was performed. Furthermore, mitochondrial DNA copy number was determined.

RESULTS

The tumors differed with regard to mitochondrial energy metabolism. Low levels of a subset of OXPHOS complexes were frequently observed in World Health Organization grade I meningiomas (percent of cases with a reduction; complex I: 63%; complex II: 67%; complex IV: 56%) and schwannomas (complex III: 40%, complex IV: 100%), whereas in neurofibromas a general reduction of all complexes was observed. In contrast, expression of complexes III and V was similar to that in normal brain tissue in the majority of tumors. Mitochondrial mass was comparable or higher in all tumors compared with normal brain tissue, whereas mitochondrial DNA copy number was reduced.

CONCLUSIONS

The reduction of OXPHOS complexes in meningiomas and peripheral nerve sheath tumors has potential therapeutic implications, since respiratory chain-deficient tumor cells might be selectively starved by inhibitors of glycolysis or by ketogenic diet.

Sellar-sphenoid sinus hemangioblastoma: case report

A very unusual case of sellar-sphenoid sinus hemangioblastoma without stigmata of von Hippel-Lindau disease is presented. Subtotal excision of tumor was done via an extended frontobasal approach. Diagnostic controversies between hemangioblastoma and angioblastic meningioma are discussed and the relevant literature reviewed.

Morphological and ultrastructural study of the histogenesis of meningeal granular cell tumors in rats

To clarify the cell of origin of granular cell tumors in the rat brain, light and/or electron microscopic examinations were performed on 40 cases of spontaneous meningeal tumors in Wistar (Jcl: Wistar) rats. The meningeal tumors were histologically subclassified into 3 types: meningothelial meningiomas (MMs), 3 cases; granular cell tumors (GCTs), 28 cases; and mixed forms (MIXs) of GCTs and MMs, 9 cases. Of these tumors, 2 MMs, 2 GCTs, and 3 MIXs were examined by transmission electron microscopy. Tumor cells of MMs were characterized by cytoplasmic intermediate filaments and prominent interdigitating cell processes often connected with cellular junctions without surrounding basal laminae. GCTs were composed of 2 cell types: granular cells with many dense bodies and filamentous cells with fine intermediate filaments. MIXs consisted of granular cells, filamentous cells, and intermediate cells. The tumor cells in GCTs and MIXs were apposed to each other and connected with cellular junctions. MIXs displayed a spectrum of cellular differentiation in that 2 MIXs had a close morphological resemblance to GCTs and the other one to MMs. These findings indicate there might be a histogenetic sequence among MMs, GCTs, and MIXs. The present study supports the suggestion that GCTs and MIXs may be variants of MMs from the meningeal arachnoid cell.

Exclusively intracranial cranial fasciitis in a child. Case report

The authors present a case of an intracranial tumor in a 7-year-old girl leading to increasing hemiparesis. The lesion arose from the dura and consisted of fibroblasts in a myxoid matrix. The diagnosis of cranial fasciitis was made. The histological, immunohistological, and ultrastructural features of the tumor are described and the differential diagnosis is discussed.

Extracranial meningioma in the parapharyngeal space

A case of extracranial meningioma in the parapharyngeal space is reported. A 24 year old woman presented with swelling and tenderness of the parapharyngeal region. A tumor was palpable in this region, and the tumor was surgically removed. Macroscopically the tumor occurred from the portion between the axis and atlas. Histologically the tumor cells, which had oval nuclei and a slightly eosinophilic cytoplasm, proliferated in fibrous connective tissues to form small nests. As the cell borders were not clear, the tumor structure appeared to be syncytium-like. Immunohistochemically the tumor cells were positive for anti-vimentin antibodies, anti-S-100 protein antibodies and anti-epithelial membrane antigen (EMA) antibodies in part. Electron microscopically the tumor cells had complex interdigitations of their adjacent plasma membranes. These were studded with many desmosomes. Bundles of intermediate filaments were visible in the cytoplasm. On the basis of the clinical, histological, immunohistochemical and electron microscopical features, the tumor was diagnosed as extracranial meningotheliomatous meningioma. The parapharyngeal space is an extremely rare location for extracranial meningioma, and our case is the first in Japan as far as we know.

Gangliosides in meningiomas: correlation of Glac2 to intermediary filament

Human meninges and 29 meningiomas were analyzed as to their glycosphingolipid composition. In the neutral fraction GSL, a mostly even distribution of mono-, di-, tri-and tetrahexoside was demonstrated. In the group of the gangliosides, Glac1 in one broad band in chromatograms occurred in almost all meningiomas; Glac2 was present in 84% of tumours. Members of the Gtn-family were only found in a small minority of tumours while various Gtet-gangliosides were detectable in nearly half of them. No constant pattern or patterns emerged and no correlation to either morphological subtype or malignancy grade could be established. Immunohistochemistry revealed focal presence of Glac2 in a pattern similar to that of vimentin expression. Semiquantitative evaluation showed good correlation between both parameters.

Fatty acid pattern of the different phosphoinositide fractions in human meningiomas

Previous studies showed no differences in the phospholipid content of human meningiomas compared to normal leptomeninges, but only a higher unsaturation degree in the individual phospholipid fractions of tumors. Inasmuch as phosphoinositides play a role in the membrane responsiveness to numerous effectors, we studied the fatty acid pattern of the different phosphoinositide fractions of 14 human meningiomas of different histological origin. The fatty acid analysis revealed remarkable differences among the histological types, and, above all, among the different phosphoinositide fractions of a single tumor class. The phosphoinositides derived from transitional meningiomas appeared to be the most saturated ones, because of their low arachidonic acid content. Furthermore, in all the meningiomas, long chain polyunsaturated fatty acids were present only in the phosphatidylinositol fractions and the polyphosphorylated compounds appeared to be significantly different from the corresponding monophosphorylated ones. The possible significance of the different fatty acid distribution in the three phosphoinositide classes is discussed.

Meningiomas differentiating to arachnoid trabecular cells: a proposal for histological subtype "arachnoid trabecular cell meningioma"

Three cases of meningiomas which had abundant small vacuoles in the tumor tissue are reported. By electron microscopy, the tumor cells exhibited long and thin processes, the tips of which were united by desmosomes. The tumor tissue was revealed to have wide extracellular spaces which corresponded to the vacuoles observed by light microscopy. In previous literature, various terms have been used when referring to this meningioma, such as microcystic meningioma or vacuolated meningioma. Since the ultrastructure of the tumor showed similarity to that of normal arachnoid trabecular cells, we propose to call the tumor "arachnoid trabecular cell meningioma" denoting its morphological nature clearly.

Primary intracerebral sarcoma in childhood: case report with electron-microscope study

A case of a primary intracerebral sarcoma is described in a 5-year-old girl. Histology and immunohistochemistry excluded the diagnosis of a leiomyosarcoma, a malignant haemangiopericytoma or a fibrosarcoma; electron-microscopical findings indicated that the origin of the sarcoma was in the pia mater.

Distribution of collagen type IV in brain tumors: an immunohistochemical study

One hundred-twenty seven human brain tumors were examined by an immunoperoxidase technique for the expression of collagen Type IV, a major constituent of basement membrane. The parenchymal components were negative for the marker protein in all tumors except for neurilemmomas which were positively stained. In every case, the antibody to collagen Type IV showed distinct staining of the vascular pattern. In gliomas, capillaries increased in number and the vascular staining increased in intensity. Fine branching capillaries and endothelial glomeruloid proliferations characteristic each of oligodendrogliomas and glioblastomas could be distinctly illustrated. In two ependymomas, marked capillary proliferation was noted in periventricular areas. Fibrillar staining was observed between the tumor cells in seven of 34 meningiomas. Pericapillary lamellar deposition of collagen Type IV suggests a vascular origin of psammoma bodies. In some malignant tumors, pial-glial membranes were disrupted and the Virchow-Robin spaces were filled with malignant cells. Collagen Type IV was absent around the stromal cells of hemangioblastomas, suggesting that these stromal cells were unrelated histogenetically with endothelial cells. Collage Type IV may be useful in the differential diagnosis between meningiomas and neurilemmomas.

Lipomatous meningioma--an uncommon tumor with distinct radiographic findings

A case of lipomatous (lipoblastic) meningioma is described. Atypical radiographic features of low density on computed tomography scanning and high intensity on T1-weighted magnetic resonance imaging corresponded to the presence of adipose tissue within the tumor. A review of the literature indicates few similar reported cases.

Attachment of vimentin filaments to desmosomal plaques in human meningiomal cells and arachnoidal tissue

Desmosomal proteins are co-expressed with intermediate-sized filaments (IF) of the cytokeratin type in epithelial cells, and these IF are firmly attached to the desmosomal plaque. In meningiomal and certain arachnoidal cells, however, vimentin IF are attached to desmosomal plaques. Meningiomas obtained after surgery, arachnoid "membranes", and arachnoid granulations at autopsy, as well as meningiomal cells grown in short-term culture have been examined by single and double immunofluorescence and immunoelectron microscopy using antibodies to desmoplakins, vimentin, cytokeratins, glial filament protein, neurofilament protein, and procollagen. In addition, two-dimensional gel electrophoresis of the cytoskeletal proteins has been performed. Using all of these techniques, vimentin was the only IF protein that was detected in significant amounts. The junctions morphologically resembling desmosomes of epithelial cells have been identified as true desmosomes by antibodies specific for desmoplakins and they provided the membrane attachment sites for the vimentin IF. These findings show that anchorage of IF to the cell surface at desmosomal plaques is not restricted to cytokeratin IF as in epithelial cells and desmin IF as in cardiac myocytes, suggesting that binding to desmosomes and hemidesmosomes is a more common feature of IF organization. The co-expression of desmosomal proteins and IF of the vimentin type only defines a new class of cell ("desmofibrocyte") and may also provide an important histodiagnostic criterion.

Meningioma of lung: first report with light and electron microscopic findings

This is the first report of a primary meningioma of the lung. The lesion was present at least 4 years prior to its operative removal. The 59-year-old patient is still healthy 2 1/2 years after operation. All examinations, including computed tomography, failed to detect another primary tumor. Light and electron microscopic findings are identical to those in endotheliomatous meningioma. The relations to the so-called minute pulmonary chemodectomas and the probable histogenesis are discussed.

Meningiomas. A light and electron microscopy study

A morphological and ultrastructural study was undertaken from a personal series of meningiomas. Especially the fine structure of the tumour has been described by the electron microscopic study of 16 meningotheliomatous and 4 fibroblastic meningiomas. In all cases, it was possible to distinguish certain cells with epithelial features such as desmosomes, microfilaments and interdigitating extensions. Also the cytological patterns of fibroblastic meningiomas usually were similar to the meningotheliomatous type, anyhow the intercellular space between the interdigitating extensions of adjacent cells was occupied by collagen-fibers. At present, it has been impossible to demonstrate the capability of the tumour cells to synthetize collagen. Since the tumour cells of both the meningiomas are substantially similar to the subarachnoid space meningocyte, it is concluded that the neoplasm rises from a cell with double potentiality for fibroblastic and epithelial differentiation.

Granulofilamentous inclusions in a meningioma

We have studied the histology, immunocytochemistry, and ultrastructure of a syncytial meningioma which contained the unusual feature of large eosinophilic intracytoplasmic inclusions. Electron microscopic examination revealed that these bodies were granular, osmiophilic masses, closely associated with cytoplasmic filaments of intermediate size. Desmosomal junctions with a somewhat abnormal morphology were also observed, and the possible relationship between the inclusions and the dense components of desmosomes is discussed. This tumor is also compared to other tumors of the central nervous system with hyaline and granulofilamentous inclusions.

The fine structure of meningiomas: an attempted classification

We examined 23 meningiomas by electron microscopy. In each case it was possible to distinguish certain cells with epithelial features (desmosomes, microfliaments, interdigitating extensions) and others with fibroblastic features (collagen fibers). Others cells of transitional form were also seen. The proportion of these cellular types is variable, making it possible to classify meningiomas into seven types of progressing gradually from a purely epithelial type to a purely fibroblastic one.-We found no important ultrastructural abnormalities in the cells. These case reports confirm the uniqueness of meningiomas, which are composed of variously shaped cells but have their origin from a single cellular type. This has double potentiality for fibroblastic and epithelial differentiation.

Extraneuraxial canine meningioma. A light and electron microscopic study

A tumor mass removed from the subcutaneous tissue of the shoulder of a dog had the light and electron microscopic features of extraneuraxial meningioma. The neoplasm probably arose from arachnoid cap cells displaced during embryogenesis.

Hemidesmosome-like intercellular specializations in human meningiomas

Desmosomes, gap junctions and tight junctions are intercellular specializations which have been described in human meningiomas. We report, in five of five meningiomas, including a pulmonary metastasis from a malignant intracranial meningioma, a fourth type of intercellular specialization which is similar to but not identical with the hemidesmosome of the epidermis. Idential intercellular specializations have been described between arachnoidal cells, but not between dural fibroblasts. The presence of the junction in human meningeal neoplasms of diverse histologic pattern supports the origin of the meningioma from arachnoidal epithelium. The consistent occurrence of these structures in a pulmonary metastasis as well as benign intracranial tumors suggests that they may be a useful morphologic marker in the differential diagnosis of putative extracranial metastatic meningiomas.

Malignant meningioma: ultrastructure and observations on histogenesis

A malignant meningioma was studied by light and electron microscopy. Histologically, the tumour was composed predominantly of spindle shaped cells arranged in interlacing bundles with numerous mitoses and much nuclear atypia. There were many necrotic foci as well as invasion of the cerebral cortex, dura mater and blood vessels. Ultrastructurally, the main findings included moderate plasma membrane interdigitation, many intracytoplasmic filaments, and junctional attachments of three kinds: desmosomes, hemidesmosomes, and zonulae adhaerentes. These subcellular features are suggestive of arachnoidal cell origin.

The angioblastic meningioma: a reappraisal of the nosological problem. Light-, electron-microscopic, tissue, and organ culture observations

The validity of the concept of the angioblastic meningioma, now in dispute, was reexamined by reviewing 79 meningeal and angioblastic tumors of the central nervous system and by comparing the fine structural characteristics and in vitro evolution of 2 typical meningiomas and 1 intracranial hemangiopericytoma. While most tumors show the consistent features of either hemangiopericytoma or hemangioblastoma, there exist transitional forms between these tumors and typical meningioma. There is also a greater degree of morphological overlap at the electron microscopic level than has been recognized up till now. In view of these findings the concept of the angioblastic meningioma deserves to be retained as a generic term to include craniospinal hemangiopericytomas and transitional forms between hemangiopericytoma, hemangioblastoma and classic meningioma. It is postulated that all these tumors share a common origin from polyblastic mesenchymal cells originating in or derived from the meninges.

Gap junctions between human meningioma cells maintained in organ culture

Intercellular junctions were commonly observed in a human syncitial meningioma maintained in organ culture for up to 44 days in vitro (DIV) using gelatin sponge foam matrices. The junctions were identified as one of three types: desmosomes; tight junctions; or gap junctions. Of the three types, gap junctions were frequently encountered and showed preservation of their characteristic ladder-like substructure. The results suggest that organ culture provides an environment that may facilitate correlation of the structure and function of gap junctions between coupled human meningioma cells.

Intracranial hemangiopericytoma: ultrastructural evidence of its leiomyoblastic differentiation

Two intracranial hemangiopericytomas revealed subcellular features of the neoplastic elements comparable to those observed in normal and neoplastic smooth muscle. These included intracytoplasmic and submembranous fusiform dense bodies associated with bundles of filaments, tapered configuration of cells with grouping of cytoplasmic organelles at nuclear poles and deposition of intercellular basal lamina-like material. These observations are consistent with the pericytic origin but opposed to the ofttimes postulated meningothelial derivation of the neoplasm.

The fine structure of so-called minute pulmonary chemodectomas

Electron microscopy was performed on several minute tumors of the type called chemodectomas, all from the lung of a single patient. The cells had a whorling pattern with extensive interdigitating cytoplasmic processes joined by desmosomes. Except for tangles of cytoplasmic fibrils, the tumor cells had few distinctive organelles. They had no endocrine-like granules and were not associated with nerves or basement membranes. The tumors had little resemblance to paragangliomas, but displayed a puzzling similarity to meningiomas. Our observations permit no definite conclusions as to the histogenesis of these lung tumors. Viewed in the light of recent physiologic studies, they cast doubt on the presence of special chemoreceptive paraganglia in the lung.

Multiple supratentorial hemangioblastomas. Case study and ultrastructural characteristics

✓ Multiple hemangioblastomas were found above the tentorium in a 62-year-old woman who first had a discrete 2.5 cm tumor removed from the superior aspect of the tentorium adjacent to the falx, and 2 years later developed two more intracranial mass lesions, one in the right parietal area, the other attached to the dura of the right frontal fossa. Histological examination of all three tumors showed precisely the same well-differentiated morphology of hemangioblastoma. Foci of extramedullary hematopoiesis were present within them. Electron microscopic examination of the last two lesions disclosed secretory granules within the tumor cells, indicative of erythropoietin production, as described previously in a hemangioblastoma. Collagen and endothelial cells were not present in quantities consistent with an angioblastic meningioma. The genesis of hemangioblastomas is discussed.

Intracerebral fibroma in an 11-month-old infant. Case report

✓ The authors report the successful surgical treatment of a primary intracerebral fibroma (fibroblastoma) in an 11-month-old boy. Related cases are also discussed.