Subependymal giant-cell astrocytoma. Case report with ultrastructural study

Tuberous sclerosis: a syndrome of incomplete tumor suppression

Tuberous sclerosis (TS) is a congenital neurocutaneous syndrome (or phacomatosis) characterized by widespread development of hamartomas in multiple organs. For affected individuals, neurological and psychiatric complications are the most disabling and lethal features. Although the clinical phenotype of TS is complex, only three lesions characterize the neuropathological features of the disease: cortical tubers, subependymal nodules, and subependymal giant cell astrocytomas. The latter is a benign brain tumor of mixed neuronal and glial origin. Tuberous sclerosis is caused by loss-of-function mutations in one of two genes, TSC1 or TSC2. The normal cellular proteins encoded by these genes, hamartin and tuberin, respectively, form a heterodimer that suppresses cell growth in the central nervous system by dampening the phosphatidylinositol 3–kinase signal transduction pathway. The authors review the clinical and neuropathological features of TS as well as recent research into the molecular biology of this disease. Through this work, investigators are beginning to resolve the paradoxical findings that malignant cancers seldom arise in patients with TS, even though the signaling molecules involved are key mediators of cancer cell growth.

Intraventricular gliomas

Gliomas are the most common primary brain tumor in adults, and those within or relating to the ventricular surface represent a less common but important subcategory. The most common intraventricular gliomas include ependymomas, SEs, and SEGAs. Other less common varieties have been reported, including chordoid gliomas, glioblastoma multiforme, and mixed glial-neuronal tumors. Each type of intraventricular glioma is associated with its own unique constellation of epidemiologic, clinical, radiologic, and pathologic defining characteristics. Each tumor type has its own management considerations and nuances with unique prognostic indicators and outcomes. The outcome for certain intraventricular gliomas (especially ependymomas) remains relatively poor. Future advancements in surgical technique are likely to have only a modest impact on improvement of outcome. Translational research aiming to advance the knowledge of tumor biology into new targeted cellular and molecular therapies holds tremendous promise to improve the overall outcome. Additionally, more thorough delineation of prognostic factors as well as modifications and refinements to radiation and chemotherapy may help to improve the still significantly poor outcomes for patients harboring these lesions. Future cooperative intra- and interinstitutional efforts between scientists and clinicians will hopefully culminate in an improved outlook and eventual cure for patients with gliomas.

Subependymal giant cell astrocytoma--a clinicopathological study of 23 cases with special emphasis on histogenesis

Subependymal giant cell astrocytomas (SEGAs) are relatively rare tumors but occur commonly in the setting of the familial syndrome of tuberous sclerosis complex (TSC). In view of its varied morphology, i.e. resemblance to astrocytic and ganglion cells, its histogenesis remains controversial. We studied 23 cases of SEGA, 19 from our own institute and 4 from NIMHANS, Bangalore. These 19 cases of SEGAs were collected over a period of 23 years (1979 to 2001), and accounted for 0.16% of intracranial tumors and 0.51% of all gliomas reported at our center. The majority of patients presented with visual disturbances (19/23, 82.6%) in the form of decreased vision (60.8%) and blindness (21.7%), generalized tonic clonic seizures (43.4%) and focal motor seizures (4.37%). Age ranged from 4 to 37 years (mean 13.2 years) with male predominance (M:F 2.2:1), and the duration of symptoms varied from 1 month to 96 months (mean 17.2 months). Lateral ventricular involvement was the most common site (91.3%), followed by the third ventricle (8.6%). Nine patients (39.1%) had stigmata of tuberous sclerosis (6 at the time of diagnosis and 3 in the follow-up period). Two patients died due to surgical complications, while the rest were alive and well in the follow-up period ranging from 3 to 264 months (mean 37.1 months). Two patients experienced recurrences, one two years and another 22 years after surgery. Microscopic examination showed varied histology consisting of sweeping bundles of spindle cells, gemistocyte and ganglion-like cells with interspersed inflammatory cell component. The inflammatory cell component on special staining turned out to be an admixture of mast cells and T lymphocytes. Six cases showed areas of necrosis and/or mitosis, but were not indicative of aggressive nature of this tumor. Immunoreactivity for GFAP, NF, S-100, NSE and synaptophysin indicates that this is a hybrid tumor with glial and neuronal differentiation. None of the tumors was immunopositive for HMB-45. The significance of the presence of T lymphocytes and mast cells is not clear. It could be related to tumor immunology and may indicate a favorable prognosis.

A subependymal giant cell astrocytoma in a cat

A 6-year-old spayed female Domestic Shorthair cat presented with a 1 to 2-month history of blindness and altered behavior. At necropsy, a 1-cm-diameter, firm white mass was found arising from the subependymal region of the right lateral ventricular wall that protruded into and partially filled the lumen. Histologically, there was a well-demarcated, expansile paraventricular neoplasm composed of moderately pleomorphic cells within a richly fibrillar matrix arranged in interlacing streams and perivascular pseudorosette-like patterns. Neoplastic cells varied in morphology from small spindloid cells to larger polygonal cells with eccentric vesicular nuclei to neuronlike cells with vesicular nuclei and prominent nucleoli. The mitotic index was low. Immunohistochemically, neoplastic cells were positive for S-100 protein, glial fibrillary acidic protein, and neuron-specific enolase and negative for neurofilament protein. Ultrastructurally, the cells contained few to abundant bundles of intermediate filaments with variable numbers of mitochondria, endoplasmic reticulum, and ribosomes. These features are characteristic of subependymal giant cell astrocytoma (SEGA) in humans. To our knowledge, this is the first reported case of SEGA in domestic animals.

Tumours of the lateral ventricle. A retrospective review of 112 cases operated upon 1970-1997

Between the years 1970 and 1997, 112 patients with tumors of the lateral ventricle were operated on at the University of Ankara, School of Medicine, Department of Neurosurgery. Seventy-one patients (63.4%) were male and 41 patients (36.6%) female. Headache (35.7%), nausea and vomiting (22.3%) were the most common presenting complaints. Papilloedema (42.9%), motor and sensory loss (25%) were the most common findings at neurological examination. Complete tumor removal was accomplished in 38.4% of the patients. Histopathologically, the most commonly seen types of the tumor were ependymoma (25%) and astrocytoma (21.4%). Among the various approach, the anterior transcortical (53.6%) and the posterior transcortical (16%) were the most commonly used. Eleven patients were reoperated for tumor recurrence. After surgery, radiation therapy was also performed on fourty-two patients. The morbidity and mortality rates were considerably higher before 1976 when the use of microneurosurgical techniques was introduced. After this, our morbidity and mortality rates decreased dramatically. The overall surgical mortality rate was 7.1% before 1976; during the last 10 years (n:46), it was 6.5%. In this report, our choice of operative approaches and the results will be discussed.

Ultrastructural pathology of glial brain tumors revisited: a review

The ultrastructural pathology of primary brain tumors of glial origin is examined. These are divided into two major groups. The first category comprises astrocytoma with the variants: fibrillary, protoplasmic, gemistocytic, and anaplastic. These are biologically aggressive tumors of a relatively high proliferative potential and include a substantial proportion of cases that transform into the most malignant secondary glioblastoma. The second category, comprised of rather benign tumors of a limited proliferative capacity and a reasonable good prognosis, includes such clinico-pathological entities as pilocytic astrocytoma, pleomorphic xanthoastrocytoma, and subependymal giant cell astrocytoma of tuberous sclerosis. There is no ultrastructural feature, however, which makes it possible to discriminate between major subclasses of astrocytes; but secondary glioblastoma cells, while still retaining the stigmata of neoplastic astrocytes, are characterized by nuclei that seem to be more indented, cisterns of the endoplastic reticulum may be distended, and intranuclear pseudoinclusions are frequently observed. Primary glioblastoma, which probably originates de novo, is characterized by poorly differentiated cells with a paucity of subcellular organelles and no obvious features of astrocytic origin. Granular cell tumor also belongs to neoplasms of astrocytic lineage and the hallmark of this entity is a cell characterized by the presence of numerous membrane-bound, electron-dense autophagic vacuoles. Its malignant analogue is the granular cell glioblastoma. Two subtypes of granular cell glioblastoma have been distinguished. The first is characterized by the presence of numerous granular, electron-dense bodies which correspond to autophagic vacuoles. The second type is characterized by numerous electron-dense, amorphous masses within cellular processes. These electron-dense inclusions are virtually indistinguishable from minute Rosenthal fibers. The pilocytic astrocytoma is virtually indistinguishable at the ultrastructural level from fibrillary astrocytomas but cells tend to be more elongated. Besides Rosenthal fibers, two types of distinctive structures are relatively common in pilocytic astrocytomas: eosinophilic hyaline droplets and round granular bodies, which are composed of large aggregates of electron-dense secondary lysosomes or small electron-dense bodies, respectively. Pleomorphic xanthoastrocytoma is characterized by astrocytes surrounded by basal membranes. It belongs to a peculiar category of astrocytic "desmoplastic" brain tumors occurring in younger patients, the common denominator for which is the presence of basal lamina. The last category in this group is subependymal giant cell astrocytoma, a tumor of bivalent (glial and neuronal) differentiation, the cells of which are characterized by the presence of peculiar crystalloids. The hallmark of oligodendroglioma is the presence of concentric arrays of membranes (so-called membrane laminations, whorls, or scrolls). A fragment of the cytoplasm sequestrated within a particular whorl may contain mitochondria, lysosomes, or abundant glycogen granules. Ependymomas are characterized by a florid picture dominated by the presence of microlumina, cilia with basal bodies (blepharoplasts), microvilli, and long, interdigitating intercellular junctions of the zonulae adherentiae type. Ganglioglioma, the last category covered by this review, is a mixed glio-neuronal tumor. While glial cells are indistinguishable from their counterparts encountered elsewhere (mostly pilocytic astrocytes), the ganglion cells are characterized by abundant intracytoplasmic dense-core vesicles, absence of intermediate filaments, and numerous microtubules. Occasionally a close apposition of ganglion cells and Rosenthal fibers is seen. Dense-core vesicles are pleomorphic and ranged in a diameter from small synaptic vesicles to large lysosome-like neurosecretory granules.

Tuber and subependymal giant cell astrocytoma associated with tuberous sclerosis: an immunohistochemical, ultrastructural, and immunoelectron and microscopic study

The cellular nature of the giant eosinophilic cells of tuber and of the cells comprising subependymal giant cell astrocytoma (SEGA) in tuberous sclerosis (TS) remains unclear. To assess the characteristics of these lesions, 13 tubers and 6 SEGA were immunohistochemically studied with glial and neuron-associated antigens. In addition to conventional ultrastructure, 6 tubers and 8 SEGA were subjected to immunoelectron microscopic study for glial fibrillary acidic protein (GFAP) and somatostatin. Eosinophilic giant cells of tubers were positive for vimentin (100%), GFAP (77%) and S-100 protein (92%); such cells were also found to a various extent to be reactive for neuron-associated antigens, including neurofilament (NF) proteins (38%) or class III beta-tubulin (77%). SEGA also showed variable immunoreactivity for GFAP (50%) or for S-100 protein (100%); NF epitopes, class III beta-tubulin, and calbindin 28-kD were expressed in 2 (33%), 5 (83%) and 4 (67%) cases, respectively. Cytoplasmic staining for somatostatin (50%), met-enkephalin (50%), 5-hydroxytryptamine (33%), beta-endorphin (33%) and neuropeptide Y (17%) was noted in SEGA, but not in tubers. Ultrastructurally, the giant cells of tubers and the cells of SEGA contained numerous intermediate filaments, frequent lysosomes and occasional rectangular or rhomboid membrane-bound crystalloids exhibiting lamellar periodicity and structural transition to lysosomes. Some SEGA cells showed features suggestive of neuronal differentiation, including stacks of rough endoplasmic reticulum, occasional microtubules and a few dense-core granules. Furthermore, in one case of tuber, a process of a single large cell was seen to be engaged in synapse formation. Intermediate filaments within a few cells of both lesions were decorated by gold particle-labeled GFAP antiserum. Within the tumor cells of SEGA, irregular, non-membrane-bound, electron-lucent areas often contained somatostatin-immunoreactive particles, whereas the latter could not be detected in tuber. The present study provides further evidence of divergent glioneuronal differentiation, both in the giant cells of tubers and the cells of SEGA. The findings of similar cells at different sites, including the subependymal zone, white matter ("heterotopias"), and cortex indirectly supports the idea that these lesions of TS result from a migration abnormality.

Crystalline inclusions in a subependymal giant cell tumor in a patient with tuberous sclerosis

Unusual crystalline cytoplasmic inclusions were encountered in tumor cells in a subependymal giant cell tumor (SEGT) in a 16-year-old girl with tuberous sclerosis. By electron microscopy, the tumor cells demonstrated typical features previously described in SEGT, including abundant dense bodies, prominent Golgi complexes, abundant mitochondria, rough and smooth endoplasmic reticulum, scattered intermediate filaments and microtubules, glycogen, and rare synaptic contacts as well as primitive intercellular junctions. The dense bodies were bound by a single membrane and were round, ovoid, irregular, or cylindric in appearance with electron-dense homogenous content or fingerprint profiles. Of note was the presence of numerous cytoplasmic rhomboidal or rectangular crystalline inclusions akin to those seen in alveolar soft part sarcoma. These inclusions measured as much as 8 microns in length and had 7-nm periodicities, often with intersecting lamellae. Rarely, the membrane-bound dense bodies showed areas of similar periodicities, indicating that the crystalline inclusions are related to and might originate from the dense bodies. While crystalline inclusions have previously been described in one patient with SEGT (Bender and Yunis, Ultrastruct Pathol 1980; 1:287-299), the inclusions in the present case were a striking feature and add to the spectrum of the ultrastructural pathology of SEGT.

Subependymal giant-cell astrocytoma in children. An unusual discrepancy between histological and clinical features

The authors describe five cases of subependymal giant-cell astrocytoma in children in which many clinical, histological, immunohistochemical, and ultrastructural features typical of this tumor were present. However, prominent focal necrosis and mitoses, features usually associated with high-grade tumors, were seen in all cases. Despite the presence of necrosis and mitoses, clinical follow-up studies have revealed a lack of aggressive tumor behavior after surgery alone. The discrepancy between the histological and clinical features in these cases is emphasized so that excessive treatment of a basically low-grade tumor may be avoided. Mast cells were seen in all five cases, often in large numbers.

Giant cell astrocytoma in tuberous sclerosis: computed tomographic findings

Clinical presentation and computed tomography (CT) findings in four tuberous sclerosis patients with large ventricular tumours situated near the foramina of Monro, and causing obstructive hydrocephalus are described. These tumours (so-called giant cell astrocytomas) demonstrated uniform post-contrast enhancement. This finding, along with their location, distinguished them from the much commoner cortical and subependymal tubers of tuberous sclerosis.

Intraventricular tumors in tuberous sclerosis

Eleven of our own cases of tuberous sclerosis with intraventricular tumor and 34 cases from the literature are reviewed. Initial symptoms and identification of tuberous sclerosis and tumor are reviewed. Results of surgical treatment, including direct radical excision and shunting are given. On gross examination, the tumor was most often loosely connected to ependyma near the foramen of Monro, causing hydrocephalus. Giant cell subependymal astrocytoma was frequently found on microscopic examination. The glial origin of the tumor is discussed and direct surgical approach of the tumor is proposed as the best treatment of these lesions.

Subependymal giant cell astrocytoma. Significance and possible cytogenetic implications of an immunohistochemical study

Twenty-two cases of subependymal giant cell astrocytoma (SGCA), five of which associated with tuberous sclerosis, were reviewed by conventional neurohistological stains and by peroxidase-antiperoxidase (PAP) immunohistochemistry for glial fibrillary acidic (GFA) protein, the 68 Kd neurofilament subunit (68 Kd-NF), and neuron-specific enolase (NSE). Neurohistological stains confirmed the presence of PTAH-positive fibrils and the absence of Nissl bodies and of neurites originating from the tumor cells. GFA protein-positive cells were present in all tumors not associated with tuberous sclerosis. However, the number of positive cells in each tumor was highly variable. GFA protein-positive cells were rare in the two SGCA accompanying tuberous sclerosis and absent in the remaining three. Neurohistological stains showed no differences between GFA protein-positive and negative cells. 68 Kd-NF-positive cells were found in six tumors. In one tumor, associated with tuberous sclerosis, it was present in the large ganglion-like cells only. NSE-positive cells were found in 13 of 18 tumors examined, including four of the five SGCA associated with tuberous sclerosis. The significance of NSE-positivity in central neuroepithelial neoplasms in respect of their possible neuronal origin remains open. This study suggests that the SGCA, especially those associated with tuberous sclerosis, include cells that are apparently unable to express GFA protein. Some of the tumor cells express the 68 Kd-NF, but this expression falls short of the complete expression of neuronal differentiation.(ABSTRACT TRUNCATED AT 250 WORDS)

Subependymal giant-cell tumor: astrocytic or neuronal?

Tissue from seven patients with tuberous sclerosis and subependymal giant-cell tumors was examined with special stains, immunohistochemistry, and electron microscopy. Immunoreactive glial fibrillary acidic protein (GFAP) was not found in the giant cells of four tumors, but was present in some tumor cells in the other three. Immunoreactive S-100 protein was present in tumor cells of six cases; it was also seen in more tumor cells than was GFAP. Electron microscopy was similar in all cases and showed that the tumor cells had numerous organelles - many dense bodies thought to be primary lysosomes, swollen mitochondria, Golgi complexes, rough and smooth endoplasmic reticulum, free ribosomes, and sparsely distributed intermediate filaments. In one case, neurosecretory granules, microvilli, and synapses were observed. In another subject, prominent, thick bundles of glial filaments were seen. These findings suggest that the tumor is made up of unique cells in addition to cells with recognizable neuronal or astrocytic features.

Computed tomography in diagnosis of intracranial tumors versus tubers in tuberous sclerosis

Intraventricular gliomas producing obstruction of the foramen of Monro were observed by computed tomography in 4 of 8 patients with tuberous sclerosis. Bilateral tumors arising from the caudate nuclei were present in one patient. Characteristic subependymal calcified tubers were also seen, but contrast enhancement occurred only in the tumors and not in the tubers. The location of the tumor prevented communication between the 2 lateral ventricles so that surgical placement of a single ventricular shunt resulted in only unilateral relief of hydrocephalus. Shunting in one case was ineffective because of high cerebrospinal fluid viscosity due to elevated protein concentration.

Ultrastructure of tuberous sclerosis: cortical tuber and subependymal tumor

Ultrastructural examination of two biopsy cases of tuberous sclerosis, a subependymal tumor and a cortical tuber, revealed giant cells with astrocytic features in both cases. These included multipolar processes containing glial filaments, glycogen, and membrane-bound dense bodies, as well as formation of hemidesmosomes with pia and vascular basement membranes. Megamitochondria were also seen within glial processes. In addition to the numerous glial-glial contacts encountered in both cases, rare neuroglial junctions suggesting aberrant synapse formation were observed within the cortical tuber. This observation, in concert with the organization of multiple small neurites along large, aberrant astrocyte processes found within the tuber, mimics features of neuroembryonic development described in lower mammals and nonhuman primates. Such a parallel in ultrastructural morphology supports a primarily dysplastic nature for the lesions in tuberous sclerosis.

Paratesticular neuroblastoma associated with subependymal giant cell astrocytoma

We describe a case of neuroblastoma presenting as a paratesticular mass in infancy. To our knowledge this is the first case of a paratesticular neuroblastoma reported in the literature. An operation combined with radiotherapy and chemotherapy has achieved long-term survival despite obvious multifocal disease. Seven years after treatment of the inital tumor the patient presented with a subependymal giant cell astrocytoma, an extremely rare neuroectodermal tumor. Discussion is directed to possible explanations for this unusual case of multifocal, metachronous neuroectodermal neoplasms.

Tuberous sclerosis - neurosurgical indications in intraventricular tumors

Thirteen cases of intraventricular tumors associated with tuberous sclerosis are described. The most common picture showed the "forme fruste", i.e. there were no signs of the typical clinical triad - metal retardation, seizures, and adenoma sebaceum - and there was usually no family history of tuberous sclerosis. There was a high incidence of increased intracranial pressure (76,9%). CT has made possible the preoperative diagnosis of an intraventricular tumor which is suggestive of tuberous sclerosis. The best surgical results were obtained by total excision of the tumor. The shunt procedures are discussed as a temporary surgery for relief of increased intracranial pressure and as a preparation of the patient for the final excision of the tumor. All the tumors were classified as subependymal giant cell astrocytomas according to the new classification of the World Health Organization.