Search results for "Meningioma"
showing 10 items of 71 documents
Pathogenetic Mechanisms of Intratumoral Hemorrhage in Meningioma: The Role of Microvascular Differentiation
2016
The transformation of normal cells into neoplastic cells is based on a series of gradual and progressive processes . One of the most important aspects underlying the tumorigenesis ist hat neoplastic proliferation needs mechanisms to ensure cancer development, bypass the body's protective strategies, and survive the apoptotic mechanisms. Subsequently, measures to promote replicative immortality and vascular support will be required. If cancer develops in an area offering excellent vascularization, pre-existing vascular circuits can supporti ts growth .Otherwise,tumor angiogenetic mechanisms will trigger new vascular networks, which will be necessary for tumor survival and expansion. The latt…
Histologic and Cytogenetic Patterns in Benign, Atypical, and Malignant Meningiomas
1995
Atypical meningiomas comprise an intermediate category of meningeal neoplasmas with some microscopic features of aggressivity and a capacity for recurrence. We present a clin ical, morphologic, and cytogenetic study of 15 meningiomas. Morphologic and cytogenetic analysis suggested the existence of morphologically typical meningiomas with normal karyotype or monosomy 22 and morphologically atypical meningiomas, with increasing chromosomal abnormalities (complex karyotype) between these two types. Present results suggest the existence of a third type of morphologically typical meningioma that lacks a phenotypical aggressivity but has a complex karyotype. These genotypical characteristics may…
Calcified Spinal Meningioma: A Lurking Danger
2017
Tumors of the spine with an intradural location have an incidence ranging from 3 to 10 per 100,000 persons per year, and intradural extramedullary tumors account for two thirds of all intraspinal neoplasms. Among these, spinal meningiomas account for 25%–46% of all spinal cord tumors. They develop from the arachnoid cells that differentiate from neural crest cells and, like cerebral meningioma, they have a slow-growing behavior. Although spinal meningiomas are not uncommon, calcified spinal meningioma is rare in spinal location. Calcified meningioma manifests with extensive matrix and tends to infiltrate the surrounding structures. It exhibits a growth pattern limited by an incompletely dev…
Impacto de la variación en el número de copias y del estado de metilación de genes supresores de tumor en las vías de progresión del meningioma
2015
El meningioma es el tumor del sistema nervioso central más frecuente en la edad adulta, con una incidencia superior al 30% y una evidente predominancia femenina. La sintomatología deriva fundamentalmente de la localización del tumor, que crece desde las células de la cubierta aracnoidea. El tratamiento es principalmente quirúrgico, y su radicalidad se relaciona clásicamente con la aparición de recidivas tumorales, que es la principal complicación que sufren los afectados. Macroscópicamente, son tumores habitualmente bien delimitados y encapsulados, de crecimiento lento, y microscópicamente la OMS los clasifica en 16 subtipos histológicos. Son tumores positivos para vimentina y EMA, y en men…
Virtual reality system for planning minimally invasive neurosurgery
2008
Object The authors report on their experience with a 3D virtual reality system for planning minimally invasive neurosurgical procedures. Methods Between October 2002 and April 2006, the authors used the Dextroscope (Volume Interactions, Ltd.) to plan neurosurgical procedures in 106 patients, including 100 with intracranial and 6 with spinal lesions. The planning was performed 1 to 3 days preoperatively, and in 12 cases, 3D prints of the planning procedure were taken into the operating room. A questionnaire was completed by the neurosurgeon after the planning procedure. Results After a short period of acclimatization, the system proved easy to operate and is currently used routinely for pre…
Contribution of thallium-201-SPECT to the grading of tumorous alterations of the brain
1992
Single photon emission computed tomography (SPECT) with thallium-201-chloride (201Tl) was used in 22 patients to assess the grade of malignancy of brain tumors. Low- and high-grade malignant gliomas could be well differentiated by calculating the Grade Index (GI), i.e., 201Tl uptake in the tumor area relative to a contralateral brain region. Low-grade gliomas (WHO-grade I-II) usually showed a GI of1.5. Tumors classified histologically as high-grade malignant (WHO-grade III-IV) had GI values greater than 1.42 and a mean value of 1.89. Until labelled amino-acid tracers for gamma-cameras become commercially available, thallium-201 brain-SPECT can provide an independent and complementary method…
Tissue characterization of benign brain tumors: Use of NMR-tissue parameters
1988
Abstract To evaluate the potentials of NMR tissue parameters for tissue characterization we investigated 68 patients with benign brain tumors. Tissue parameters were accurately measured by a recently developed interlaced triple sequence. Each individual tumor was characterized by a set of three numbers (relaxation times T 1 and T 2 and proton density Rho). Different tumors exhibited significant overlaps of the three tissue parameters. Therefore a reliable prediction of the histological diagnosis based on the quantitative analysis of tissue parameters alone was not possible. T 2 -prolongation correlated well with water content and “regressive changes” in meningiomas and neuromas.
Epigenetic changes underlie the aggressiveness of histologically benign meningiomas that recur
2019
Meningiomas are the most frequent primary brain tumor. Usually, they are curable by surgery, but even after seemingly complete resection, some low-grade lesions recur. Despite recent improvements, signatures having prognostic value in grade I tumors remain poorly characterized. The frequency and delicate location of these tumors suggest that the risk of recurrence might be more accurately predicted. Herein, we show an easy way to evaluate the methylation status of meningiomas and its correlation with the prognosis of the disease. A series of 120 meningiomas, including primary tumors and recurrences, were analyzed histopathologically, and 24 tumor suppressor genes (TSGs) were studied by meth…
Association of loss of 1p and alterations of chromosome 14 in meningioma progression
2004
Meningiomas are usually benign tumors; however, they can recur after surgical resection and occasionally show histologic progression to a higher grade II and III malignancy. The second most frequently reported genetic abnormality after 22q loss is deletion of 1p, although alterations in 9q, 10q, and 14q are also implicated in meningioma progression. Fourteen tumors comprising six benign, four atypical, and four malignant meningiomas were examined by means of cytogenetic and fluorescence in situ hybridization analysis. All tumors showed losses in different regions of 1p, with 1p11, 1p13, 1p21, 1p22, 1p32, and 1q21 breakpoints; eight tumors also presented alterations of chromosome 14. Five of…
Occupation and risk of glioma, meningioma and acoustic neuroma: results from a German case-control study (interphone study group, Germany)
2010
Background: Several epidemiological studies have investigated the association between occupation and brain tumour risk, but results have been inconclusive. We investigated the association between six occupational categories defined a priori: chemical, metal, agricultural, construction, electrical/electronic and transport, and the risk of glioma, meningioma and acoustic neuroma. Methods: In a population-based case-control study involving a total of 844 cases and 1688 controls conducted from 2000 to 2003, detailed information on life-long job histories was collected during personal interviews and used to create job calendars for each participant. Job title, job activity, job number, and the s…