Telomerase expression in intracranial tumours: prognostic potential for malignant gliomas and meningiomas.
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AIM: To evaluate the diagnostic value of telomerase expression in intracranial tumours. METHODS: 98 surgical specimens from different neoplasms were analysed by the telomeric repeat amplification protocol (TRAP) and the presence of telomerase compared with the histological diagnosis and the proliferation index. RESULTS: A high degree of positivity for telomerase activity was found in glioblastomas and atypical/anaplastic meningiomas. Telomerase activity was poorly detected in anaplastic astrocytomas. CONCLUSIONS: The TRAP assay seems to be a valuable index for identifying meningeal tumours with aggressive behaviour. (+info)
Clinical value of 24-hour delayed imaging in somatostatin receptor scintigraphy for meningioma.
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Somatostatin receptor scintigraphy (SRS) using 111In-octreotide has proven useful in patients suspected of having meningiomas. Delayed imaging is regularly performed up to 24 h postinjection. However, this procedure is time consuming and expensive. Therefore, we investigated whether 24-h imaging may be omitted in these patients. METHODS: After clinical examination and standard MRI, 71 patients were suspected of having 92 meningioma lesions. Before surgery, all patients underwent SRS after intravenous injection of 200 MBq (5.4 mCi) 111In-octreotide. Planar whole-body images were obtained at 10 min and 1, 4 and 24 h, and SPECT was performed at 4 and 24 h. Results of SRS in all lesions were evaluated with respect to histology and time of image acquisition. RESULTS: SRS yielded 58 true-positive, 20 true-negative and 14 false-negative results, with the false-negatives all less than 5 mL (2.3+/-2.1 mL) in volume. In 52 of 58 true-positive lesions (89.7%), diagnosis could be established by 4-h imaging without further information by 24-h imaging. In 10 of the 52 lesions, SPECT was necessary to confirm planar findings. Imaging at 24 h was necessary in only 6 of 58 true-positive lesions (10.3%): 3 patients who had intracranial relapse of meningioma (volume < 5 mL) and 3 who had spinal meningioma. Thus, a diagnosis of intracranial meningioma could be established in 52 of 55 lesions (95%) using a 4-h imaging protocol. CONCLUSION: With a 4-h acquisition protocol that includes SPECT imaging, SRS yields sufficient information in patients suspected of having intracranial meningiomas. Delayed imaging at 24 h is recommended only for patients who have small meningiomas (volume < 5 mL), spinal localizations or negative SRS at 4 h. (+info)
Tentorial meningioma encroaching the transverse sinuses and sigmoid sinus junction area associated with dural arteriovenous fistulous malformation: a case report.
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A 62-year-old woman was evaluated for tinnitis and headache. Magnetic resonance imaging and angiography revealed the coexistence of a tentorial tumor encroaching the junction of the right transverse-sigmoid sinuses, and dural arteriovenous fistulous malformation (AVFM) of the right transverse sinus. AVFM was not manipulated at all during the surgery. The pathology was fibroblastic meningioma. Postoperatively, the dural AVFM completely disappeared on follow-up angiography. The fistulas were occluded also after surgery, even though there was no manipulation of the AVFM. It is suggested that the right dominant transverse-sigmoid sinuses are partially occluded by tentorial meningioma, developing the dural arteriovenous fistula of the right transverse sinus. An acquired origin of the dural AVFM was suggested in this case. (+info)
Long-term magnetic resonance imaging follow-up of asymptomatic sellar tumors. -- their natural history and surgical indications.
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Serial magnetic resonance (MR) images and clinical symptoms were analyzed in 23 patients with sellar lesions, who were followed up without initial therapy for mass reduction to evaluate their natural history and surgical indication for these lesions. The patients were aged 17 to 78 years (mean 47.3 years) and the follow-up period was 1.5 to 11.6 years (mean 5.1 years). Lesions were divided into two types based on the MR imaging findings, regardless of their histological types. Type C was cystic with or without enhancement of the smooth and thin wall. Type S had enhanced solid components. Ten patients had Type C tumors. Three patients presented with sudden onset of headache. The tumor size spontaneously decreased with intensity change, indicating pituitary apoplexy as the trigger of the onset and intensity change. Four patients presented with the visual disturbance which improved with the reduction of tumor size, but three patients deteriorated and required surgery. The operation revealed Rathke's cleft cyst. The remaining three patients were found incidentally and have been asymptomatic without MR imaging changes. Thirteen patients had Type S tumors. Six patients of nine with 14 mm or larger tumors developed symptomatic tumor enlargement over the follow-up period of 1.2 to 8.6 years (mean 4.9 years) and required treatment. The remainder showed no change. Type C tumors frequently shrink or even disappear spontaneously. We can justify conservative follow-up of Type C tumors in patients with no or only transient symptoms. Type S tumors, larger than 14 mm in size, need closer observation or treatment because they often enlarge and become symptomatic. (+info)
Retinoic acid stimulates meningioma cell adhesion to the extracellular matrix and inhibits invasion.
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Meningiomas are tumours derived from the arachnoid and pia mater. During embryogenesis, these membranes develop from the migrating craniofacial neural crest. We have previously demonstrated that meningiomas have characteristic features of embryonic meninges. Craniofacial neural crest derivatives are affected during normal development and migration by retinoic acid. We speculated, therefore, that meningioma cell migration and invasion would be affected in a similar way. In this study we investigated the mechanisms of invasion and migration in meningiomas and the effects of retinoic acid (RA). We found that low doses of RA inhibit in vitro invasion in meningioma cells, without affecting cell proliferation or viability. The matrix metalloproteinases MMP-2 (72 kDa gelatinase) and MMP-9 (92 kDa gelatinase), which play a key role in invasion in other tumours, are not affected by RA. RA inhibits cell migration on collagen I and fibronectin. A possible mechanism for these effects is provided by the fact that RA strongly stimulates adhesion of meningioma cells to extracellular matrix substrates. As in vitro invasion, migration and decreased adhesion to the extracellular matrix correlate with the clinical manifestation of tumour invasion, we conclude that RA induces a non-invasive phenotype in meningioma cells. (+info)
Examination of low-incidence brain tumor responses in F344 rats following chemical exposures in National Toxicology Program carcinogenicity studies.
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Neoplasms in the brain are uncommon in control Fischer 344 (F344) rats; they occur at a rate of less than 1% in 2-yr toxicity/carcinogenicity studies. Furthermore, only 10 of nearly 500 studies conducted by the National Toxicology Program (NTP) showed any evidence of chemically related neoplastic effects in the brain. Generally, the brain tumor responses were considered equivocal, because the characteristics of potential neurocarcinogenic agents (such as statistically significant increased incidences, decreased latency and/or survival, and demonstration of dose-response relationships) were not observed. A thorough examination, including comparisons with a well-established historical database, is often critical in evaluating rare brain tumors. Chemicals that gave equivocal evidence of brain tumor responses were generally associated with carcinogenicity at other sites, and many chemicals were mutagenic when incubated with metabolic activating enzymes. Other factors that were supportive of the theory that marginal increases in brain tumor incidence were related to chemical exposure were that (a) some of the tumors were malignant, (b) no brain neoplasms were observed in concurrent controls from some studies, and/or (c) brain tumors were also seen following exposure to structurally related chemicals. In 2-yr studies in F344 rats (studies conducted by the NTP), equivocal evidence of carcinogenicity was observed for the following 9 chemicals: isoprene, bromoethane, chloroethane, 3,3'-dimethylbenzidine dihydrochloride, 3,3'-dimethoxybenzidine dihydrochloride, furosemide, C.I. direct blue 15, diphenhydramine hydrochloride, and 1-H-benzotriazole. Glycidol was the only chemical evaluated by the NTP with which there was clear evidence of brain tumor induction in F344 rats. Clarification of the potential neurocarcinogenic risks of chemicals that produce equivocal evidence of a brain tumor response in conventional 2-yr rodent studies may be aided by the use of transgenic mouse models that exhibit genetic alterations that reflect those present in human brain tumors as well as by the use of in utero exposures. (+info)
Preoperative embolization of intracranial meningiomas with a fibrin glue preparation.
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BACKGROUND AND PURPOSE: Preoperative embolization expands the spectrum of meningioma that can be operated on safely. Our goal was to achieve the distalmost loading of the vascular bed and confluent tumor necrosis with a fibrin glue preparation in the preoperative embolization of meningiomas. METHODS: Between 1992 and 1997, 80 patients with a meningioma had diagnostic angiography with a standard transfemoral Seldinger technique, performed with a 6F guiding catheter and digital subtraction angiography. Preoperative embolization was carried out in the same session with an additional microcatheter system. Fibrin glue was the only component used. In all cases, CT was performed immediately after embolization; in nine patients, MR imaging was also performed. RESULTS: Angiography verified the elimination of tumor blush in all patients. The high-density areas seen on postembolization CT scans, caused by the fibrin glue dispersed in the embolized supply area, were found to be necrotic at surgery and were easily removed by suction. Two (2.5%) of the 80 patients had complications associated with embolization that resulted in neurologic deficits. CONCLUSION: The most effective preoperative embolization of tumors requires a distalmost loading of the vascular bed. Fibrin glue, which is easy to use and safe to handle, causes confluent tumor necrosis within the injected vascular territory. (+info)
Posterior fossa surgery in the sitting position in a pregnant patient with cerebellopontine angle meningioma.
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Primary brain tumours and pregnancy rarely occur together; meningioma and pregnancy is rarer still. We describe a 30-yr-old woman in the 25th week of pregnancy who underwent surgery in the sitting position for a large cerebellopontine angle meningioma that was compressing and displacing the pons and medulla. The surgical procedure and postoperative period were uneventful. This case demonstrates that when absolutely necessary, anaesthesia and neurosurgery for posterior fossa lesions can be successful during the second trimester of pregnancy. Furthermore, if indicated and if the operating team is experienced, the operation can be performed safely with the patient in the classical sitting position. It is emphasized that continuous and attentive monitoring of the mother and fetus are essential. (+info)