The Monocyte/Macrophage Infiltrate in 35 Medulloblastomas: A Paraffin-Wax Study

We have studied formalin fixed, paraffin-wax embedded tissue from 35 medulloblastomas, collected over 23 years (27 non-desmoplastic and 8 desmoplastic) with KP1 and Mac387 two monoclonal anti-monocytes/macrophage (M/Ms) antibodies recommended for use on paraffin wax embedded tissue. In non-desmoplastic medulloblastomas, outside areas of necrosis, M/Ms were detected in 50% of cases with KP1 and 52% with Mac387. M/Ms were seen In 100% of desmoplastic medulloblastomas with both antibodies. Semiquantitative assessment revealed that, on average, desmoplastic tumors had at least three times as many Infiltrating M/Ms as non-desmoplastic tumors. There was no significant difference in the findings with the two antibodies or, between recently embedded and « older » tumors. The findings may be indicative of the presence of a host M/Ms immune response in medulloblastoma, which may be more accentuated in desmoplastic medulloblastomas. Furthermore, we conclude that these antibodies are quite suitable for the study of infiltrating M/Ms, thus lessening (but not obviating) the need for frozen tissue for immunohistological studies.

Added Value of Arterial Spin-Labeling MR Imaging for the Differentiation of Cerebellar Hemangioblastoma from Metastasis

BACKGROUND AND PURPOSE

In adults with only cerebellar masses, hemangioblastoma and metastasis are the 2 most important differential diagnoses. Our aim was to investigate the added value of arterial spin-labeling MR imaging for differentiating hemangioblastoma from metastasis in patients with only cerebellar masses.

MATERIALS AND METHODS

This retrospective study included a homogeneous cohort comprising patients with only cerebellar masses, including 16 hemangioblastomas and 14 metastases. All patients underwent enhanced MR imaging, including arterial spin-labeling. First, the presence or absence of a hyperperfused mass was determined. Next, in the hyperperfused mass, relative tumor blood flow (mean blood flow in the tumor divided by blood flow measured in normal-appearing cerebellar tissue) and the size ratio (size in the arterial spin-labeling images divided by size in the postcontrast T1WI) were measured. To validate the arterial spin-labeling findings, 2 observers independently evaluated the conventional MR images and the combined set of arterial spin-labeling images.

RESULTS

All patients with hemangioblastomas and half of the patients with metastases presented with a hyperperfused mass (P < .001). The size ratio and relative tumor blood flow were significantly larger for hemangioblastomas than for metastases (P < .001 and P = .039, respectively). The size ratio revealed excellent diagnostic power (area under the curve = 0.991), and the relative tumor blood flow demonstrated moderate diagnostic power (area under the curve = 0.777). The diagnostic accuracy of both observers was significantly improved after the addition of arterial spin-labeling; the area under the curve improved from 0.574 to 0.969 (P < .001) for observer 2 and from 0.683 to 1 (P < .001) for observer 2.

CONCLUSIONS

Arterial spin-labeling imaging can aid in distinguishing hemangioblastoma from metastasis in patients with only cerebellar masses.

Medulloblastoma Genotype Dictates Blood Brain Barrier Phenotype

The childhood brain tumor, medulloblastoma, includes four subtypes with very different prognoses. Here, we show that paracrine signals driven by mutant β-catenin in WNT-medulloblastoma, an essentially curable form of the disease, induce an aberrant fenestrated vasculature that permits the accumulation of high levels of intra-tumoral chemotherapy and a robust therapeutic response. In contrast, SHH-medulloblastoma, a less curable disease subtype, contains an intact blood brain barrier, rendering this tumor impermeable and resistant to chemotherapy. The medulloblastoma-endothelial cell paracrine axis can be manipulated in vivo, altering chemotherapy permeability and clinical response. Thus, medulloblastoma genotype dictates tumor vessel phenotype, explaining in part the disparate prognoses among medulloblastoma subtypes and suggesting an approach to enhance the chemoresponsiveness of other brain tumors.

Coagulation and angiogenic gene expression profiles are defined by molecular subgroups of medulloblastoma: evidence for growth factor-thrombin cross-talk

BACKGROUND

The coagulation system becomes activated during progression and therapy of high-grade brain tumors. Triggering tissue factor (F3/TF) and thrombin receptors (F2R/PAR-1) may influence the vascular tumor microenvironment and angiogenesis irrespective of clinically apparent thrombosis. These processes are poorly understood in medulloblastoma (MB), in which diverse oncogenic pathways define at least four molecular disease subtypes (WNT, SHH, Group 3 and Group 4). We asked whether there is a link between molecular subtype and the network of vascular regulators expressed in MB.

METHODS

Using R2 microarray analysis and visualization platform, we mined MB datasets for differential expression of vascular (coagulation and angiogenesis)-related genes, and explored their link to known oncogenic drivers. We evaluated the functional significance of this link in DAOY cells in vitro following growth factor and thrombin stimulation.

RESULTS

The coagulome and angiome differ across MB subtypes. F3/TF and F2R/PAR-1 mRNA expression are upregulated in SHH tumors and correlate with higher levels of hepatocyte growth factor receptor (MET). Cultured DAOY (MB) cells exhibit an up-regulation of F3/TF and F2R/PAR-1 following combined SHH and MET ligand (HGF) treatment. These factors cooperate with thrombin, impacting the profile of vascular regulators, including interleukin 1β (IL1B) and chondromodulin 1 (LECT1).

CONCLUSIONS

Coagulation pathway sensors (F3/TF, F2R/PAR-1) are expressed in MB in a subtype-specific manner, and may be functionally linked to SHH and MET circuitry. Thus coagulation system perturbations may elicit subtype/context-specific changes in vascular and cellular responses in MB.

Anatomical variation of superior petrosal vein and its management during surgery for cerebellopontine angle meningiomas

No systematic study is yet available that focuses on the surgical anatomy of the superior petrosal vein and its significance during surgery for cerebellopontine angle meningiomas. The aim of the present study was to examine the variation of the superior petrosal vein via the retrosigmoid suboccipital approach in relation to the tumor attachment of cerebellopontine angle meningiomas as well as postoperative complications related to venous occlusion. Forty-three patients with cerebellopontine angle meningiomas were analyzed retrospectively. Based on the operative findings, the tumors were classified into four subtypes: the petroclival type, tentorial type, anterior petrous type, and posterior petrous type. According to a previous anatomical report, the superior petrosal veins were divided into three groups: Type I which emptied into the superior petrosal sinus above and lateral to the internal acoustic meatus, Type II which emptied between the lateral limit of the trigeminal nerve at Meckel's cave and the medial limit of the facial nerve at the internal acoustic meatus, and Type III which emptied into the superior petrosal sinus above and medial to Meckel's cave. In both the petroclival and anterior petrous types, the most common vein was Type III which is the ideal vein for a retrosigmoid approach. In contrast, the Type II vein which is at high risk of being sacrificed during a suprameatal approach procedure was most frequent in posterior petrous type, in which the superior petrosal vein was not largely an obstacle. Intraoperative sacrificing of veins was associated with a significantly higher rate of venous-related phenomena, while venous complications occurred even in cases where the superior petrosal vein was absent or compressed by the tumor. The variation in the superior petrosal vein appeared to differ among the tumor attachment subtypes, which could permit a satisfactory surgical exposure without dividing the superior petrosal vein. In cases where the superior petrosal vein was previously occluded, other bridging veins could correspond with implications for the crucial venous drainage system, and should thus be identified and protected whenever possible.

Morphological analysis of vascular density in ependymomas

Ependymomas generally show slow growth rate and are associated with a long clinical history. In some cases however the biology of these tumours is considered to be unpredictable on the basis of histologic criteria. Density of microvessels was shown to serve in various malignant neoplasms as a prognostic factor that correlates with increased risk of metastasis and overall free survival. Some data suggest that density of blood vessels may be of prognostic value also in patients with neuroepithelial tumours. The aim of this study was to determinate whether that observation can be applied to ependymomas. The materials included 51 ependymomas G2 and G3 according to the WHO classification. Vasculature was visualized immunohistochemically in paraffin-embedded sections of tumour samples with CD31 and FVIII antibody. Density of blood vessels was calculated using a computed image analyzing system. The data were statistically evaluated. The density of blood vessels in anaplastic (WHO G3) ependymomas was shown to be significantly higher than that in WHO G2 type of the tumour, while there was no statistical difference between subtypes of WHO G2 ependymomas. The results suggest a connection between density of vasculature and the degree of histological malignancy in gliomas of ependymal derivation.

Advanced reactive astrogliosis associated with hemangioblastoma versus astroglial-vascular neoplasm ("angioglioma")

Hemangioblastomas of the central nervous system are often accompanied by a cyst exhibiting an extensive astroglial reaction. The cyst's wall might be composed of various astroglial elements including reactive pilocytic or gemistocytic and hypertrophic astrocytes. The small tissue samples composed of compact gliotic tissue are sometimes nonrepresentative for primary hemangioblastoma tumour and might be confused with both pilocytic and diffuse infiltrative astrocytoma. Moreover, vascular anomalies of hemangioblastoma-like pattern could be combined with true neoplastic glial proliferation. Such association of glioma with certain types of vascular anomalies has been designated as angioglioma. In the current study we evaluated a series of hemangioblastomas accompanied by advanced astrogliosis of adjacent brain tissue. In some cases the histopathological features of pilocytic gliosis with numerous Rosenthal fibres and eosinophilic granular bodies strongly suggest the diagnosis of pilocytic astrocytoma. One tumour was identified as an angioglioma exhibiting a combination of hemangioblastoma-like tissue and pilocytic astrocytoma. The recognition of such an entity is important in differential tumour diagnosis and prognosis.

Capillary physiology of human medulloblastoma: impact on chemotherapy

BACKGROUND

Advances in the treatment of medulloblastoma have largely been attributed to the introduction of chemotherapy, although Phase III trials have shown advantages for chemotherapy only in subgroups. Because the efficacy of chemotherapy depends on tumor vascularization, the vascular physiology of human medulloblastomas was evaluated.

METHODS

Seven patients with histologically proven medulloblastomas underwent measurements of capillary permeability and vascular plasma volume using contrast-enhanced dynamic computer tomography. Regional blood flow was measured in 5 patients using xenon computed tomography (CT).

RESULTS

The capillary permeability-surface product for water-soluble compounds ranged from 1.7 +/- 5.5 to 17.6 +/- 12.3 muL/g/min with a mean of 10.5 +/- 6.3 microL/g/min. The vascular plasma volume ranged from 0.02 +/- 0.021 to 0.045 +/- 0.049 mL/g with a mean of 0.03 +/- 0.01 mL/g. The efflux rate ranged from 0.012 +/- 0.007 to 0.065 +/- 0.064 1/min with a mean of 0.039 +/- 0.020 1/min. Regional tumoral blood flow showed a mean of 19.86 +/- 6.8 mL/100g/min as compared with normal cerebellum with 45.4 +/- 12.03 mL/100g/min (P < .005).

CONCLUSIONS

The current study demonstrated a low capillary permeability and blood flow in medulloblastomas that could explain the limited response rates of partially resected tumors even after aggressive high-dose chemotherapy, as recently reported.

Three-dimensional (3D) reconstruction and quantitative analysis of the microvasculature in medulloblastoma and ependymoma subtypes

In the World Health Organisation (WHO) classification of tumours of the nervous system, four main histopathological subtypes of medulloblastomas (classic medulloblastoma, desmoplastic medulloblastoma, medulloblastoma with extensive nodularity and advanced neuronal differentiation and large cell/anaplastic medulloblastoma) as well as of ependymal tumours (low-grade ependymoma, anaplastic ependymoma, myxopapillary ependymoma and subependymoma) are recognised. Under the hypothesis that the microvascular architecture of tumours is a reflection of the histopathological subtype, we performed three-dimensional reconstructions of the microvasculature in these subtypes of medulloblastomas and ependymal tumours using computerised image analysis. In addition, we quantitatively assessed three microvascular parameters (number, area, perimeter) in these neoplasms. Three-dimensional reconstructions showed a dense pattern of irregular vessels in classic and large cell medulloblastoma. In desmoplastic medulloblastoma and medulloblastoma with extensive nodularity, the vessels were more unevenly distributed and organised around the nodular areas. Classic medulloblastoma and large cell medulloblastoma had on average the largest vessel area and perimeter. The highest number of vessels was seen in classic medulloblastoma and medulloblastoma with extensive nodularity. Three-dimensional analysis of ependymal tumours showed that low-grade ependymoma had larger but fewer vessels compared to anaplastic ependymoma, while myxopapillary ependymoma had a complex, heterogeneous pattern of vessels and subependymoma few but regular vessels. In ependymal tumours, the highest values for vessel number, vessel area and vessel perimeter were found in anaplastic ependymoma and the lowest values in subependymoma. We conclude that our three-dimensional reconstructions shed unprecedented light on the tumour vasculature in medulloblastomas and ependymal tumours and expect that such reconstructions are helpful tools for further studies on tumour angiogenesis.

Three-dimensional reconstruction of tumor microvasculature: simultaneous visualization of multiple components in paraffin-embedded tissue

Three-dimensional (3D) visualization of microscopic structures may provide useful information about the exact 3D configuration, and offers a useful tool to examine the spatial relationship between different components in tissues. A promising field for 3D investigation is the microvascular architecture in normal and pathological tissue, especially because pathological angiogenesis plays a key role in tumor growth and metastasis formation. This paper describes an improved method for 3D reconstruction of microvessels and other microscopic structures in transmitted light microscopy. Serial tissue sections were stained for the endothelial marker CD34 to highlight microvessels and corresponding images were selected and aligned. Alignment of stored images was further improved by automated non-rigid image registration, and automated segmentation of microvessels was performed. Using this technique, 3D reconstructions were produced of the vasculature of the normal brain. Also, to illustrate the complexity of tumor vasculature, 3D reconstructions of two brain tumors were performed: a hemangioblastoma and a glioblastoma multiforme. The possibility of multiple component visualization was shown in a 3D reconstruction of endothelium and pericytes of normal cerebellar cortex and a hemangioblastoma using alternate staining for CD34 and alpha-smooth muscle actin in serial sections, and of a GBM using immunohistochemical double staining. In conclusion, the described 3D reconstruction procedure provides a promising tool for simultaneous visualization of microscopic structures.

Tentorial Schwannoma: A Case Report and Review of the Literature

INTRODUCTION

Schwannomas are most often found in association with the eighth cranial nerve, but may also arise from any other cranial nerve. They are rarely found in an intra-parenchymal location. Unusual locations for intracranial schwannomas have also been reported in association with neurofibromatosis.

CLINICAL PRESENTATION

A 23-year-old male without von Recklinghausen's disease presented with intermittent dizziness and difficulty swallowing. Past medical history was significant for a motor vehicle accident (MVA) without loss of consciousness 6 months prior. Magnetic resonance imaging revealed a large tentorial-based tumor. At surgery the origin of the tumor was clearly the tentorium, and while the trigeminal nerve was displaced, it easily separated from the mass. There was no attachment to any other cranial nerve in the immediate vicinity and postoperative cranial nerve examination was unremarkable. Pathological review was consistent with schwannoma.

CONCLUSION

While there are few reported cases of tentorial-based schwannoma, these tumors have been noted in unusual locations within the intracranial vault, and clinicians should be aware of this diversity of origin.

Evaluation of vascular supply with angio-computed tomography during intra-arterial chemotherapy for brain tumors

We report the utility of a combined angiography and computed tomography (angio-CT) system in assessing drug distribution to the tumor during intra-arterial chemotherapy for metastatic brain tumors in a 65-year-old man. Although digital subtraction angiography did not clearly show tumor perfusion in two cerebellar tumors, angio-CT provided definite tumor perfusion in the complicated vascular territory, and anticancer agents were infused based on its findings. To our knowledge, however, this application for intra-arterial chemotherapy of brain tumors has not been previously described.

Prognostic significance of anaplasia and angiogenesis in childhood medulloblastoma: a pediatric oncology group study

The purpose of this study was to investigate whether quantitative assessment of cytologic anaplasia and angiogenesis may predict the clinical prognosis in medulloblastoma and stratify the patients to avoid both undertreatment and overtreatment. Medulloblastomas from 23 patients belonging to the Pediatric Oncology Group were evaluated with respect to some prognostic variables, including histologic assessment of nodularity and desmoplasia, grading of anaplasia, measurement of nuclear size, mitotic cell count, quantification of angiogenesis, including vascular surface density (VSD) and microvessel number (NVES), and immunohistochemical scoring of vascular endothelial growth factor (VEGF) expression. Univariate and multivariate analyses for prognostic indicators for survival were performed. Univariate analysis revealed that extensive nodularity was a significant favorable prognostic factor, whereas the presence of anaplasia, increased nuclear size, mitotic rate, VSD, and NVES were significant unfavorable prognostic factors. Using multivariate analysis, increased nuclear size was found to be an independent unfavorable prognostic factor for survival. Neither the presence of desmoplasia nor VEGF expression was significantly related to patient survival. Although care must be taken not to overstate the importance of the results of this single-institution preliminary report, pathologic grading of medulloblastomas with respect to grading of anaplasia and quantification of nodularity, nuclear size, and microvessel profiles may be clinically useful for the treatment of medulloblastomas. Further validation of the independent prognostic significance of nuclear size in stratifying patients is required.

Fetal capillary haemangioblastoma: an exceptional tumour. A review of the literature

We report a case of a fetal haemangioblastoma located in the cerebellopontine angle. On prenatal ultrasonographic examination a hyperechogenic and heterogeneous mass with a major vascularization on colour Doppler imaging was observed. It increased progressively and laminated the cerebellum. A neoplastic tumour was suspected but its extent into the cerebral peduncle was unclear. Diagnosis was made at autopsy using histological, immunohistochemical and flow cytometric evaluation. Haemangioblastoma is an exceptional congenital tumour, which is either sporadic or integrated in von Hippel-Lindau disease (VHLD). We discuss the obstetrical management of prenatal brain tumours and the genetic counselling of haemangioblastoma.

Intratumoral hemorrhage from a posterior fossa tumor after cardiac valve surgery--case report

A 53-year-old woman suffered intracranial hemorrhage from a cerebellar tumor several days after aortic valve replacement. Surgical intervention was not performed because the patient refused blood infusion for religious reasons (Jehovah's Witness). Instead, the anticoagulation therapy was interrupted for a week, and the patient was conservatively treated with administration of mannitol and steroid. The anticoagulation therapy was restarted 7 days after the hemorrhage. The intratumoral hemorrhage did not recur, and no systemic embolism occurred. The tumor was treated with gamma knife radiosurgery 6 weeks after the hemorrhage, under the radiological diagnosis of meningioma. Anticoagulation therapy is routinely used for patients following cardiac surgery to decrease the risk of thromboembolic complications, but also increases the risk of hemorrhagic events which often involve the central nervous system. Temporary discontinuation of anticoagulation therapy is an option for intratumoral hemorrhage in patients with replacement heart valves, and patients with known brain tumors should be informed about the risk of intracranial hemorrhage before cardiac surgery.

Tentorial vascularization in solid hemangioblastoma--case report

A 40-year-old female was admitted to the hospital with complaints of headache worsening gradually over a 1-month duration. Her past history included surgery to treat a left cerebellar cystic lesion 3 years before, and an untreated small solid right supracerebellar lesion of 1 cm diameter. On admission, magnetic resonance imaging showed that the right cerebellar lesion had grown to approximately 4 cm diameter abutting the tentorium and causing obstructive hydrocephalus. She also had two more small lesions, a right supratentorial solid lesion with cystic component near the splenium and an intramedullary cystic lesion at the C-2 level. Right suboccipital craniectomy was done. The vascular attachments between the superior aspect of the tumor and the tentorium were coagulated and the tumor was totally removed. C1-2 laminectomy was also performed to drain the intramedullary cyst. The patient deteriorated and lost consciousness with respiratory arrest 6 hours postoperatively and was reoperated for intracerebellar hematoma due to oozing from the tentorial vessels. Histological investigation revealed hemangioblastoma. Dural tentorial vascular attachments in solid hemangioblastomas located subjacent to the tentorium may cause early postoperative complications of hematoma at the site of vascular attachment following the resection. Computed tomography study in the early postoperative period is helpful to identify this problem.

High microvessel density in primitive neuroectodermal brain tumors of childhood

Microvessel density (MVD), a measure of tumor angiogenesis, has been shown to correlate significantly with overall and progression-free survival outcomes in various cancers including astrocytic brain tumors. To assess if the MVD is an independent prognostic factor in primitive neuroectodermal tumors (PNET) of the central nervous system, formalin-fixed paraffin-embedded tumor sections of 78 children with PNET were studied by CD34 immunohistochemistry to highlight endothelial cells. Microvessel density was determined in the most active area of neovascularization according to well-established methods. While it was shown that MVD showed considerable inter-tumor variability (median 75; range 20-345 microvessels per 0.7 mm2 field), no significant associations were found between MVD and metastasis or survival outcomes. We conclude that many PNETs are highly vascular CNS tumors, indicating potent angiogenic activity. Therefore, these tumors would be good candidates for antiangiogenic strategies. However, MVD determined in the most active area of neovascularization is not a predictor of metastatic potential or survival outcomes in childhood PNET.

Distinct differences in binding capacity to saccharide epitopes in supratentorial pilocytic astrocytomas, astrocytomas, anaplastic astrocytomas, and glioblastomas

We monitored the expression of glycan-binding sites on a panel of 10 biotinylated neoglycoconjugates by means of quantitative computer-assisted microscopy to further study the molecular mechanisms in the extensive infiltration of the surrounding brain parenchyma by most astrocytic tumors. Three distinct histological compartments were analyzed for each of the 108 astrocytic tumors (15 pilocytic astrocytomas (WHO grade I), 25 astrocytomas (WHO grade II), 30 anaplastic astrocytomas (WHO grade III), and 38 glioblastomas (WHO grade IV) included in our series. These compartments were tumors (nonperivascular tumor astrocytes), perivascular tumor astrocytes, and blood vessel walls. Clear differences were observed between the pilocytic and the diffuse astrocytic tumors. Furthermore, malignant progression in the latter category was paralleled by a decrease in cells' ability to bind distinct sugar epitopes, especially the D-GalNAc(alpha1-3)-D-GalNAc-beta1-R determinant of the Forssman pentasaccharide in tumors, the alpha-L-fucose in perivascular tumor areas, and the beta-D-glucose in tumor vessel walls. Markedly, the level of binding site expression for alpha-D-mannose decreased in the tumors, the perivascular tumor areas, and the vessel walls. These glycohistochemical results imply the functional relevance of protein-carbohydrate interactions in this tumor system.

Pediatric medulloblastoma: prognostic value of p53, bcl-2, Mib-1, and microvessel density

The aim of this study was to retrospectively assess the prognostic value of p53 and bcl-2 protein expression, cell proliferation index (Mib-1 index), and tumor microvessel density (factor VIII-related antigen) in pediatric medulloblastoma patients. Tumor specimens of 55 patients (age 2-18 years) with medulloblastoma treated with a curative intent between 1972 and 1991 were studied. Slides of paraffin embedded tissue were stained with monoclonal antibodies (mAb) and examined under high power light microscopy for the presence of immunoreactivity. Microvessel density was scored both in the area of most intense staining ('Angio-max') and in 3 additional randomly selected areas. The sum of these 4 scores was termed 'Angio-total'. 'Angio-max' and 'Angio-total' were evaluated separately by two independent investigators to assess reproducibility. None of the parameters studied, i.e. p53 or bcl-2 expression, Mib-1 index or microvessel density scores were associated with patient survival. Microvessel scores between observers were significantly but weakly correlated, with correlation coefficients (r) < 0.5 for both 'Angio-max' and 'Angio-total'. Leptomeningeal spread at diagnosis was the only independent factor associated with a poor survival (p = 0.003). There was no association of leptomeningeal metastasis with any of the biological markers tested in this study.

Hemangioblastomas with blood supply from the dural arteries--two case reports

Hemangioblastomas are benign vascular tumors that often occur in the cerebellum, and are located near the pia mater. The blood supply is usually received through the pia mater, and rarely through the external carotid artery. The present cases of hemangioblastoma received blood supply from the external carotid artery (occipital artery) and a branch of the internal carotid artery (carotico-tympanic artery or artery of Bernasconi Cassinari) through the dural branches. The dural arteries were not the main feeders in either case, but preoperative embolization of the occipital artery contributed to minimum bleeding during the operation in one case. Incomplete resection of hemangioblastoma is related to multicentricity of the tumors, small mural nodules, or brain stem involvement. Angiography is valuable for demonstrating arterial supply to small or multiple mural nodules. Conventional angiography is necessary for investigation of the external carotid artery branches.

Angiogenic histogenesis of stromal cells in hemangioblastoma: ultrastructural and immunohistochemical study

Controversy regarding the origin of characteristic stromal cells (SC) is responsible for the placement of hemangioblastoma as a single entity in the category of "tumors of uncertain histogenesis" in the current WHO classification of brain tumors. This subclassification of hemangioblastoma is, to a large extent, a consequence of a remarkable antigenic heterogeneity of SC demonstrated in many, often contradictory immunohistochemical studies. In contrast, most of the electron microscopic studies demonstrated a number of features indicating angiogenic nature of SC and, therefore, hemangioblastoma. This study reevaluated the histogenesis of SC, applying immunohistochemistry as well as electron microscopy and immunoelectron microscopy. Immunohistochemical studies confirmed most of the previous results indicating a very frequent expression of vimentin, S-100 protein, neuron-specific enolase, and cytokeratins. SC were less commonly immunoreactive for desmin, factor XIIIa, and Ricinus communis lectin receptors, and only occasionally for factor VIII and Ulex europeus lectin. They were negative for other markers of endothelial, neuronal, glial, neuroendocrine, and smooth muscle differentiation. Approximately 1% of SC showed Ki67 immunoreactivity, indicating their slight proliferative activity, consistent with the benign nature of the tumor. In contrast to the inconclusive results of the immunohistochemistry, electron microscopy demonstrated a clear relationship of SC to endothelial cells, smooth muscle cells, and pericytes. Occasional SC were found within the vascular lumina. SC often showed intracellular caveolae consistent with the formation of early capillary lumina. Moreover, occasional SC contained small Weibel-Palade bodies positive for factor VIII in immunoelectron microscopy. SC represent a heterogeneous population of abnormally differentiating mesenchymal cells of angiogenic lineage, with some morphological features of endothelium, pericytes, and smooth muscle cells. Occurrence of SC in hemangioblastoma could be related to a limited ability of angioformative stromal cells to develop an architecture of capillary lumina integrated with the vascular network of the tumor. Hemangioblastoma should be reclassified and included together with other vascular tumors of the central nervous system.

Different vascular patterns of medulloblastoma and supratentorial primitive neuroectodermal tumors

Astrocytoma vasculature patterns differ according to histological grade of malignancy with glioblastoma multiforme (WHO grade IV) showing most extensive endothelial proliferation. Here, we determined whether the vascular patterns of medulloblastoma and supratentorial primitive neuroectodermal tumors (PNETs), which can be hardly distinguished histopathologically, differ. We evaluated the spatial organization of vessels in medulloblastomas and PNETs using antibodies to von Willebrand factor (vWF) and CD34. Medulloblastoma capillaries showed slight endothelial cell hyperplasia. Microvessels sprouted from the capillaries and formed glomeruloid clusters. There were areas with chains of unopposed endothelial cells (3-10 cells). Supratentorial PNETs had highly branched capillaries with extensive endothelial cell hyperplasia. Glomeruloid arrays of microvessels extended from the capillaries. Small fragments of endothelial tubes were scattered throughout the tumor. Therefore, medulloblastomas and supratentorial PNETs showed different spatial organization of tumor vessels which can be used for differentiation of each tumor entity. These vascular patterns may reflect different tumor derived angiogenic stimuli.

An intracranial aneurysm on the feeding artery of a cerebellar hemangioblastoma. Case report

A case of cerebellar hemangioblastoma with a coexistent arterial aneurysm on the feeding artery of the tumor is reported. The patient presented with an acute onset of headache, loss of consciousness, and left-sided hemiparesis due to a posterior fossa hemorrhage found adjacent to a hemangioblastoma. Four-vessel angiography revealed an aneurysm on the anterior inferior cerebellar artery (AICA), which was the main feeding vessel of the hemangioblastoma. Successful total excision of the hemangioblastoma and clipping of the AICA aneurysm achieved in a one-stage operation was demonstrated on postoperative angiography.

Tumor devascularization by intratumoral ethanol injection during surgery. Technical note

Preoperative reduction in tumor vascularity has been accomplished previously by selective catheterization of tumor vessels and delivery of occlusive materials. The results of percutaneous infusion of vertebral hemangiomas and other vascular lesions led the authors to speculate that rapid devascularization of tumors by direct injection of ethanol (ETOH) could be used to reduce bleeding and facilitate resection during surgery. Thus, the use of intratumoral injection of ETOH and its effects on tumor hemostasis and resectability were examined. Four patients received direct injection of ETOH into either a spinal epidural (two renal cell carcinomas and one rhabdomyosarcoma) or a large cerebellar neoplasm (hemangioblastoma). Intraoperative perfusion of the tumors with ETOH produced immediate blanching and devascularization and enhanced visualization and resection. Incremental tumor devascularization is achieved by careful injection of small amounts of ETOH directly into the lesion, producing immediate and complete regional tumor devascularization. Use of this technique reduces intratumoral bleeding and enhances the ease and effectiveness of resection.

Expression of vascular endothelial growth factor and its receptors in pilocytic astrocytoma

Vascular endothelial growth factor (VEGF), a potent angiogenic and vascular permeability factor, is important in the angiogenesis of glioblastoma. A major difference between pilocytic astrocytoma, a grade I tumor, and the grade II fibrillary astrocytoma is the vascular proliferation, highly vascularized stroma, and great propensity for cyst formation in the former. In order to explore factors regulating such angiogenesis and cyst formation in pilocytic astrocytoma, we examined expression of VEGF and its receptors (KDR and Flt-1) using in situ hybridization. In all 14 cases a high level of VEGF transcripts could be demonstrated. These were found in specific regions, namely, in the tumor cyst wall, in areas of hyaline cystic degeneration, in stellate reticulated astrocytes around microcysts in the biphasic compact and loose areas, and in tumor cells with degenerative pleomorphic multicoated nuclei. KDR and Flt-1 were expressed in the tumor vasculature, with particularly high levels seen in coiled young proliferating vessels, especially those in the cyst wall. Given the known angiogenic and vascular permeability activities of VEGF, we propose that VEGF plays an important role in molding the characteristic morphologic features of this tumor, namely, the formation of cysts, microcystic pattern, hyaline cystic degeneration, hyaline vessels, and vascular proliferation. Mechanisms that block the VEGF pathway could constitute a potential therapeutic strategy for the treatment of this tumor.

Hypervascularity in Lhermitte-Duclos disease--case report

A 61-year-old male presented with a hypervascular variant of dysplastic gangliocytoma (Lhermitte-Duclos disease) manifesting as gait disorder. Computed tomography and magnetic resonance imaging both showed enhancement of the tumor after injection of contrast medium. Angiography demonstrated a tumor stain. Histological examination showed a double-layered structure comprising an outer layer of myelinated axons and an inner layer of dysplastic granular cells, and numerous dilated thin-walled blood vessels. Partial resection of the tumor resulted in resolution of the neurological deficit.

Pathology, genetics and cell biology of hemangioblastomas

Hemangioblastomas are highly vascularized tumors of not well-defined histological origin which are frequently associated with cysts. They arise preferentially in cerebellum, medulla and spinal cord and are histologically indistinguishable from vascular lesions in the retina (so-called angiomatosis retinae). Hemangioblastomas are the most frequent manifestations of the von Hippel-Lindau (VHL) disease, an autosomal-dominant inherited cancer syndrome but also occur as sporadic non-hereditary tumors. The VHL tumor suppressor gene has recently been cloned and enormous progress has been made towards the understanding of molecular biology and biological function of the VHL gene. Germline mutations in VHL patients, as well as somatic mutations in different tumors, including hemangioblastomas, have been identified, its ability to act as a tumor suppressor in vivo has been confirmed, and interaction with transcription factors Elongin B and C leading to inhibition of transcriptional elongation has been demonstrated. The mechanism underlying neovascularization and cyst formation in hemangioblastomas and how this is linked to inactivation of the VHL tumor suppressor gene is not known. However, the finding of dramatic up-regulation of vascular endothelial growth factor (VEGF), a potent endothelial cell growth factor with vascular permeability-inducing activity, in stromal cells and the corresponding receptors, VEGFR-1 and VEGFR-2, in tumor endothelial cells suggests that angiogenesis and cyst formation in hemangioblastomas may be regulated by this signaling pathway via a paracrine mechanism.

Vascular endothelial growth/permeability factor expression in human glioma specimens: correlation with vasogenic brain edema and tumor-associated cysts

Peritumoral vasogenic brain edema (PVBE) is a common accompaniment of malignant gliomas. It results from microvascular extravasation of plasma fluid and proteins through the interendothelial spaces. Tumor-associated cysts (TACs) are observed more commonly with benign gliomas that are not associated with PVBE. This study investigates the hypothesis that these morphologically distinct epiphenomena of microvascular extravasation are linked by a common pathophysiological mechanism involving vascular endothelial growth/permeability factor (VEG/PF), which has been implicated in vascular leak phenomena including ascites, malignant effusions, and brain edema. Furthermore, VEG/PF has been isolated from cultured glioma cells, and both VEG/PF protein and messenger RNA transcripts are expressed in brain tumor tissue. To further elucidate the relationship of VEG/PF to PVBE and TACs, the authors examined 34 pathological specimens for VEG/PF expression. Nineteen primary low-grade tumors, 11 primary high-grade tumors, and four gliosis controls were immunostained with a polyclonal anti-VEG/PF immunoglobulin G antibody. Magnetic resonance imaging was used to quantitate PVBE and to determine the presence of TACs and tumor enhancement. The study revealed that eight VEG/PF-negative specimens exhibited no significant edema, whereas 26 VEG/PF-positive tumors exhibited either significant PVBE or TACs. Notably, eight of nine benign TACs that were not associated with PVBE immunostained positive for VEG/PF. These data indicate a high degree of correlation between VEG/PF expression by gliomas and the occurrence of PVBE or TACs, irrespective of tumor grade, thus supporting VEG/PF's pivotal role as the common pathophysiological link between these processes.

Vascular contrast enhancement in Lhermitte-Duclos disease: case report

We report a patient with surgically proven Lhermitte-Duclos disease. The radiologic and pathologic features of this cerebellar lesion are reviewed, including the newly reported presence of vascular contrast enhancement within the mass.

Cerebellar hemangioblastoma with intracystic hemorrhage--case report

A 45-year-old male presented with sudden onset of severe headache, mild disorientation, and gait disturbance due to intracystic hemorrhage from a cerebellar hemangioblastoma. He was successfully treated with ventricular drainage followed by total removal of the tumor. Reported cases of intracranial hemangioblastoma with massive hemorrhage show male predominance, tend to be solid rather than cystic, and occur in supratentorial more than infratentorial locations. Thin-walled and dilated vessels in the present and other cases were a possible cause of hemorrhage. Massive hemorrhage from hemangioblastoma is rare but needs prompt treatment because of the relatively high mortality.

Detection and quantification of vascular endothelial growth factor/vascular permeability factor in brain tumor tissue and cyst fluid: the key to angiogenesis?

In primary malignant brain tumors increased vascularity and marked edema strongly suggest a possible role of the vascular endothelial growth factor/vascular permeability factor (VEGF/VPF). This was confirmed by earlier in situ hybridization studies, by analysis of the expression of the mitogen in different subsets of glioblastoma cells, and by the fact that the VEGF/VPF receptor flt-1 (fms-like tyrosine kinase) is up-regulated in tumor cells in vivo. To assess and quantify the expression of the VEGF/VPF gene and of the receptor gene, 26 surgical specimens of brain tumor tissue from 24 patients were analyzed. In most malignant gliomas, the expression level of the VEGF/VPF gene is elevated and can be increased up to 20- to 50-fold in comparison with low-grade tumors. Using polymerase chain reaction-based amplification, it could be shown that the messenger RNAs of three different VEGF/VPF forms are synthesized in tumor tissue samples. Northern blot studies revealed that in some samples a significant expression of the gene coding for placenta growth factor, a growth factor closely related to VEGF/VPF, was observed. In addition, using a radioreceptor assay it was possible to detect high VEGF/VPF-like activity in the cyst fluids of brain tumors, indicating the accumulation of the mitogen and permeability factor in brain tumor cysts. Further investigations revealed that astrocytoma and glioblastoma cells in culture express the VEGF/VPF gene and secrete the VEGF/VPF protein, whereas gene expression of the two known VEGF/VPF receptors, kinase insert domain-containing receptor and flt-1, could not be detected. These data support previous reports, which stated that VEGF/VPF acts as a paracrine growth and permeability factor in brain tumors and may contribute to tumor growth by initiating tumor angiogenesis.

Gliosis of the eighth nerve transitional region in patients with cerebellopontine angle schwannoma

The central-peripheral transitional region (TR) of the eighth nerve root was obtained from 8 patients with cerebellopontine angle schwannoma and investigated by light microscopy, electron microscopy, and immunohistochemistry. As a control, the TRs of 6 autopsy patients without any otologic disease were studied. Astrocytic proliferation at the TR was more prominent in the schwannoma patients than in the normal controls. Mild gliosis of the mantle zone of the TR was found in 5 schwannoma patients and moderate gliosis was noted in 3. The distribution of capillaries at the TR differed between the schwannoma patients and the normal controls. In the schwannoma patients, capillaries were rarely found in the mantle zone of the TR but were densely clustered at the glial fringe zone, especially near its border with the peripheral nervous tissue. Stasis of the capillaries in the glial fringe zone was frequently noted. These histological findings may indicate the occurrence of gliosis in response to eighth nerve degeneration. We suggest that there is increased susceptibility of the eighth nerve to injury at the TR in patients with schwannoma.

Cerebral venous drainage via the ophthalmic veins in the Sturge-Weber syndrome

We describe a 23-year-old girl with an extremely uncommon form of cerebral venous drainage and cerebellar leptomeningeal angiomatosis as a possible variant of the Sturge-Weber syndrome. Extensive congenital port-wine stains all over the body, hypoplastic left renal and subclavian and iliac veins, cardiomegaly and ptosis and hypoplasia of the left kidney had been recognised in early childhood. She rapidly developed signs of intracranial hypertension. CT and MRI showed a right medial temporal lesion. Angiography revealed cerebellar pial angiomatosis with enlarged medullary veins and no functioning sigmoid sinuses or jugular veins. Cerebral venous drainage was via enlarged ophthalmic veins. Although the intracranial venous abnormalities were characteristic of the Sturge-Weber syndrome anomalies beyond the encephalofacial territory suggested a more complex developmental abnormality.

Posterior fossa venous angiomas with drainage through the brain stem

PURPOSE

To describe 11 cases of posterior fossa venous angiomas with drainage through the brain stem.

METHODS

Eleven cases of posterior fossa venous angioma with drainage through the brain stem were evaluated using MR. Correlation with known routes of venous drainage for the cerebellum and brain stem is made.

RESULTS

Six of the 11 venous angiomas were found in the cerebellum, four in the brain stem; one involved both the cerebellum and brain stem. The cerebellar venous angiomas drained to subependymal veins about the fourth ventricle and dorsal pons. These then connected with an enlarged transmesencephalic or transpontine vein, to drain anteriorly to the anterior pontine veins. The brain stem angiomas had variable drainage depending on location. Evidence of hemorrhage was seen in five cases.

CONCLUSION

Cerebellar and brain stem venous angiomas have several potential routes of drainage, including an enlarged vein traversing the pons, midbrain, or medulla. A knowledge of the normal venous anatomy of this region helps to understand the occurrence of these uncommon routes of venous drainage.

Tumor vascularity in the brain: evaluation with dynamic susceptibility-contrast MR imaging

PURPOSE

To evaluate the efficacy of dynamic susceptibility-contrast magnetic resonance (MR) imaging for diagnosis of intraaxial brain tumors.

MATERIALS AND METHODS

Ten patients with such tumors (two hemangioblastomas, five low-grade astrocytomas, and three glioblastomas) underwent examination at 1.5 T. After bolus injection of 0.15 mmol/kg gadopentetate dimeglumine, gradient-echo MR images were obtained every 3.6 seconds for 90 seconds. Region-of-interest analyses were performed in all tumors.

RESULTS

The greatest loss in signal intensity during the first pass of the contrast agent was seen in hemangioblastomas; low-grade astrocytomas had the least loss. The differences in integration of change in the T2* relaxation rate were significant among the three types of tumor (hemangioblastomas vs low-grade astrocytomas, P < .001; hemangioblastomas vs glioblastomas, P < .005; and glioblastomas vs low-grade astrocytomas, P < .02) and indicated differences in vascularity.

CONCLUSION

Dynamic susceptibility-contrast MR imaging can provide useful hemodynamic information about intraaxial brain tumors that is not provided by standard MR imaging and therefore contributes to the differential diagnosis.

Fibrohistiocytic differentiation in capillary hemangioblastoma

Seven cases of capillary hemangioblastoma from the cerebellum and spinal cord were studied by immunohistochemical methods to determine the origin of the stromal cells. A subpopulation of factor XIIIa-positive tumor cells was a constant feature in hemangioblastomas. These stellate or spindle-shaped cells transformed into typical vacuolated stromal cells. Factor VIII-related antigen was limited to the vascular endothelium. Glial fibrillary acidic protein was present only in entrapped astrocytes. Staining for alpha-1-antitrypsin (alpha 1AT) and alpha-1-antichymotrypsin (alpha 1 ACT) was occasionally observed in stromal cells. It was concluded that the factor XIIIa-positive stromal cells in capillary hemangioblastoma indicate fibrohistiocytic differentiation, which is part of the differentiation spectrum of hemangiopericytomas.

Cocaine-induced intratumoral hemorrhage: case report and review of the literature

A unique case is described of a 28-year-old man who had seizures and a hemorrhage within a previously unsuspected cerebellopontine angle schwannoma within minutes of nasally inhaling cocaine. A review of the literature on cocaine-induced seizures and cocaine-induced cerebral hemorrhage is also given.

Spatial misregistration of vascular flow during MR imaging of the CNS: cause and clinical significance

Spatial misregistration of signal recovered from flowing spins within vascular structures is a common phenomenon seen in MR imaging of the CNS. The condition is displayed as a bright line or dot offset from the true anatomic location of the lumen of the imaged vessel. Its origin is the time delay between application of the phase- and frequency-encoding gradients used to locate spins within the plane of section. The principal condition necessary for the production of spatial misregistration is flow oblique to the axis of the phase-encoding gradient. Flow-related enhancement (entry slice phenomenon), even-echo rephasing, and gradient-moment nulling contribute to the production of the bright signal of spatial misregistration. Familiarity with the typical appearance of flow-dependent spatial misregistration permits confirmation of a vessel's patency; identification of the direction of flow; estimation of the velocity of flow; and differentiation of this flow artifact from atheromas, dissection, intraluminal clot, and artifacts such as chemical shift.

Repetitive intratumoral hemorrhage in medulloblastoma. A case report

An 8-year-old girl experienced five repeated hemorrhagic episodes around the cerebellar vermis. Surgical specimens histologically showed abnormal vascular components invaded by tumor cells. Autopsy disclosed medulloblastoma disseminating in the subependymal zone of the ventricles. An atypical clinical course is reported with special attention to the cause of hemorrhage.

[Ultrastructure of capillary permeability in human brain tumor: disseminated and metastatic medulloblastoma]

The ultrastructure of the tumor vessels of primary cerebellar, subarachnoidal disseminated and extraneural metastatic medulloblastomas was studied. They were compared with those in glial, nonglial and metastatic brain tumors which have been previously reported. Twelve surgical specimens were examined. Seven tumors were limited to the vermis, the floor of the fourth ventricle and the cerebellar hemispheres. Four gross nodule seedings were demonstrated in the cerebral and spinal subarachnoid space. One metastasis was demonstrated in the subclavicular lymph node. Ultrathin section of those tumors and replica specimens were studied under the transmission electron microscope. The tumor vessels of primary medulloblastoma and glial tumors had nonfenestrated capillaries and were morphologically similar to normal brain capillaries. On the other hand, the tumor vessels of disseminated and metastatic medulloblastoma, nonglial tumors, and metastatic brain tumors had fenestrated capillaries. These findings were anticipated because the arachnoid membrane and lymph nodes have fenestrated capillaries. The presence of fenestration suggests that the tumor vessels of disseminated and metastatic brain tumors resemble the blood vessels found in normal arachnoid membrane and lymph nodes.

[The astrocyte-endothelial interface in cerebellar astrocytoma]

The astrocyte-endothelial interface is a component of the anatomical blood-brain barrier in the central nervous system and is of interest in neoplastic lesions. We, therefore, investigated the fine structure of this interface in five, well-differentiated cerebellar astrocytomas. The astrocyte-endothelial interface in cerebellar astrocytomas revealed various abnormalities. The perivascular space is usually wide and contains various amounts of collagen fibers, fibroblasts and pericytes. The basal lamina of the endothelial cell is mostly single-layered and continuous, but sometimes multilayered and discontinuous. The basal lamina of the neoplastic astrocytic cell is usually single-layered and continuous, but is occasionally absent in foci. The basal lamina of the endothelial cell is more prominent than that of the astrocyte. The neoplastic astrocyte has not so well developed cell junctions and poorly formed peripheral expansions of the processes. The relationship between the basal lamina of the endothelial cell and that of the astrocyte in cerebellar astrocytomas is compared to that in ependymomas.

Posterior fossa hemangioblastomas: MR imaging

The magnetic resonance (MR) imaging findings of 18 surgically proved posterior fossa hemangioblastomas (15 patients) were retrospectively analyzed and correlated with computed tomographic (ten patients) and angiographic (eight patients) findings. Thirteen tumors were located in the cerebellar hemisphere, three in the vermis, and two in the medulla with associated syrinxes. Three patients had von Hippel-Lindau disease, two of whom had multiple cerebellar hemangioblastomas. Seven hemangioblastomas appeared as solid tumors, six as solid masses with central cysts, and five as cysts with mural nodules. Abnormal tumor vessels, with characteristic signal void, were demonstrated in 13 tumors. Associated hemorrhage was present in four tumors. Although angiography is usually required for the diagnosis and preoperative assessment of this tumor, MR imaging demonstration of a posterior fossa mass with abnormal vessels should suggest the diagnosis of hemangioblastoma. Moreover, the combination of a peripheral posterior fossa cyst with a mural nodule supplied by enlarged vessels may be pathognomonic.

[Acoustic neurinoma presenting with repeated intratumoral hemorrhage. Case report]

A case of acoustic neurinoma with multiple intratumoral hemorrhages is reported. A 56-year-old male noted sudden hearing reduction in his left ear in October of 1985. The diagnosis of a local physician was sudden deafness. About 10 months later, he had two episodes of severe headache without nausea or vomiting. The patient was hospitalized in October of 1986. Neurological examination cerebellar ataxia. cerebellar ataxia. Plain and enhanced computed tomography revealed only an unremarkable low-density area at the left cerebellopontine angle. In contrast, magnetic resonance imaging (MRI) clearly demonstrated a large (3 x 4 x 5 cm), multicystic tumor in the site. On exposure of the tumor at surgery, most of the cysts were found to be filled with a dark red or xanthochromic fluid. The tumor was completely removed following numerous cyst punctures to decrease its volume. There was no evidence of subarachnoid hemorrhage. Histological examination showed a typical acoustic neurinoma. The cyst wall contained numerous telangiectasia-like lesions. The initial symptom of this patient was sudden hearing loss, which is an atypical manifestation of acoustic neurinoma. The massive intratumoral hemorrhage was thought to be caused by telangiectatic lesions in the cyst wall. MRI clearly demonstrated the hemorrhagic cysts within the tumor, especially in the posterior fossa.

Ultrastructural study of hemangiomas. 3. Specific endothelial granules in the cerebellar hemangioblastoma

We report a case of cerebellar hemangioblastoma in a 45-year-old man. To our knowledge, only two papers have been reported previously on the cystic inclusions other than Weibel-Palade bodies in the endothelial cells, and this is the first reported case of a hemangioblastoma exhibiting large, cystic endothelial inclusions with microtubular subunits. The function of these inclusions is obscure.

Ultrastructure of cerebellar capillary hemangioblastoma. V. Large pinocytic vacuolar bodies (megalopinocytic vesicles) in endothelial cells

Large pinocytic vacuolar bodies (megalopinocytic vesicles) containing electron-dense granulo-fibrillary material, not previously described in micro-vascular endothelium of brain tumors, were observed in endothelial cells of all five cases of cerebellar hemangioblastoma studied ultrastructurally. They were present in 23% of a total of 132 capillary profiles studied. Some were prominent and aggregated to occupy a large portion of the endothelial cytoplasm. Unlike the ordinary pinocytic vesicles in endothelial cells, they were distributed predominantly in the vicinity of the nucleus and surrounded by abundant organelles. They were irregular and usually several times larger than macropinocytic vesicles. The larger vacuolar bodies were often surrounded by bundles of microfilaments which often anchored on their limiting membrane. They coexisted frequently with Weibel-Palade bodies and occasionally fused with them. Convergence of coated vesicles and micropinocytic vesicles with the vacuolar bodies was present. However, there was no direct contact between the vacuolar bodies and Golgi apparatus, rough and smooth endoplasmic reticulum and mitochondria. The vacuolar bodies were closely associated with pericytic foot processes. It was suggested that they were formed by invagination of the abluminal cytoplasmic membrane with engulfed extracellular material and migrated internally. Discharge of their contents into the vascular lumen and interendothelial space was observed. Some had a disrupted membrane with a suggestion of release of contents into the cytoplasmic matrix. Their function is unknown, but they may serve as a specific vehicle of transport or digestive mechanism in microvascular endothelium under certain pathophysiological conditions, such as neoplasm, to meet the increasing metabolic demands.

Cerebellopontine angle meningiomas: clinical manifestations and diagnosis

Cerebellopontine angle (CPA) meningiomas constitute about 1% of intracranial meningiomas. The clinical aspects of a series of 32 patients with surgically confirmed CPA meningiomas are analyzed. The most common symptoms at the time of the initial evaluation were from the eighth cranial nerve (unilateral hearing loss--24 patients, vertigo or imbalance--19 patients, tinnitus--11 patients), and the fifth cranial nerve (altered sensation--9 patients, facial pain--5 patients). On examination, the most common findings were absent caloric response (19 patients), nystagmus (16 patients), diminished facial sensation (14 patients), ataxia (13 patients), reduced hearing (9 patients), and facial weakness (9 patients). There was often a long interval from the onset of symptoms to the correct diagnosis of a tumor. Brain stem auditory evoked potentials, blink reflex testing, posterior fossa myelography, computerized tomographic scanning, and angiography were abnormal in all patients in whom the test was done, but all tests were not performed on all patients. Computerized tomographic scanning and angiography are important for definitive diagnosis and for planning surgical treatment. The histopathology of the temporal bone was studied in three patients with meningiomas in the region of the internal auditory meatus.

Ultrastructure of Cerebellar Capillary Hemangioblastoma. I. Weibel-Palade Bodies and Stromal Cell Histogenesis

Ultrastructural study of three cases of cerebellar capillary hemangioblastoma demonstrated three major component cells: endothelial cells, pericytes and stromal cells. The stromal cells exhibited ultrastructural features reminiscent of the endothelial cells. Weibel-Palade bodies, cylindrical cytoplasmic organelles specific to endothelial cells, were found in the endothelial cells and stromal cells, but not in the pericytes. The finding supported the concept that stromal cells are closely related to endothelial cells and are likely derived from the angiogenic mesenchymal cells. Since von Willebrand protein has been shown to be concentrated in Weibel-Palade bodies, the finding of these bodies in the stromal cells provided a morphological evidence for the immunocytochemical expression of factor VIII/von Willebrand factor of the stromal cells in those cases in which it has been reported.

Haemangioblastoma with multiple dural arterial supply. Case report

A case of primary haemangioblastoma with a marked blood supply from multiple meningeal branches of the internal and external carotid arteries is reported, and the clinical implication of detailed angiographic study of unusual feeders in this highly vascular tumour is discussed.