Angiomatous Meningioma Research Articles

Combined 68Ga-NOTA-PRGD2 and 18F-FDG PET/CT Can Discriminate Uncommon Meningioma Mimicking High-Grade Glioma.

Uncommon pathological subtypes of meningioma may present with severe peritumoral brain edema and mimic high-grade glioma (HGG). In a prospective cohort study of Ga-NOTA-PRGD2 PET/CT to evaluate glioma, we occasionally observed that a combination of Ga-NOTA-PRGD2 and F-FDG was able to differentiate these 2 lesion types. From 2013 to 2016, 21 patients suspected of HGG by MRI were recruited for evaluation using Ga-NOTA-PRGD2 PET/CT. Brain F-FDG PET/CT was performed within 3 days for comparison, and the tumor was surgically removed. The PET results were compared with integrin αvβ3 expression and microvascular density quantification of tumor samples. Of the 21 recruited patients, 5 patients were finally pathologically diagnosed as uncommon meningioma with severe peritumoral brain edema, including chordoid meningioma (n = 1), angiomatous meningioma (n = 1), and mixed angiomatous and microcystic meningioma (n = 3). Sixteen were diagnosed as HGG. All the meningioma lesions (n = 5) exhibited intense and homogeneous Ga-NOTA-PRGD2 uptake with higher SUVmax on Ga-NOTA-PRGD2 PET (1.64-7.86; mean ± SD, 4.23 ± 2.48) than the HGG lesions (0.81-2.99; mean ± SD, 1.57 ± 0.33; P = 0.0047). Moreover, the uptake ratios of Ga-NOTA-PRGD2 over F-FDG, normalized as lg100 * SUVmax (RGD / FDG), in the uncommon meningiomas were significantly higher than those in HGG (1.87 ± 1.36 vs 1.04 ± 0.87, P = 0.0001). A cutoff value of 1.58 was able to discriminate between these lesion types. There were positive correlations among the expression level of integrin αvβ3, microvascular density, and the tumor-to-background ratio derived from Ga-NOTA-PRGD2 PET (P < 0.05). This study reveals a specific imaging pattern of uncommon meningioma mimicking HGG, in which Ga-NOTA-PRGD2 PET provided added value to F-FDG PET.

Preoperative Assessment of Pathologic Subtypes of Meningioma and Solitary Fibrous Tumor/Hemangiopericytoma Using Dynamic Computed Tomography: A Clinical Research Study

Solitary fibrous tumors (SFTs)/hemangiopericytomas (HPCs) are highly vascularized tumors well known for malignant, invasive, and highly vascular features. To date, several studies have reported the preoperative imaging findings of SFTs/HPCs. In this study, computed tomography (CT) tumor values acquired from dynamic CT scan were selected to determine the tumor pathology of highly vascular tumors, such as SFTs/HPCs. We conducted a retrospective study on patients with pathologically diagnosed meningiomas and SFTs/HPCs who had undergone a dynamic contrast CT scan. We assessed and compared the CT values of these tumors according to the pathology. From a total of 34 patients, 30 patients with meningiomas and 4 patients with HPCs were included. The mean CT values of SFTs/HPCs and angiomatous meningioma were statistically significantly higher than those of the other meningioma subtypes (P= 0.003). We also performed receiver operating characteristic curve analyses to detect an appropriate cutoff point for the CT value to differentiate tumor pathology, and the calculated threshold was 161 Hounsfield units (HU) (sensitivity, 100%; specificity, 75%; area under the curve, 0.87; 95%, CI 0.75-0.99). This study showed that obtaining a CT value is useful in determining highly vascular tumor pathology preoperatively. When considering neurosurgical extra-axial tumor removal, and when the CT value of tumors is >161 HU, then highly vascular tumors such as SFTs/HPCs or angiomatous meningiomas are likely, and this should be considered prior to surgical intervention and for risk assessment.

Intracranial Angiomatous Meningioma: Case Report and Literature Review

Angiomatous meningioma (AM) is a rare subtype of meningioma characterized by highly vascular tumor tissue comprising predominantly variable sized hyalinized blood vessels. This manuscript describes a case of intracranial Angiomatous meningioma and reports briefly its clinical, radiological, histopathological and therapeutic characteristics through a literature review.

The role of three-dimensional pseudo-continuous arterial spin labelling in grading and differentiating histological subgroups of meningiomas

To evaluate the usefulness of pseudo-continuous arterial spin labelling (pCASL) imaging in grading and differentiating histological subtypes of meningiomas. In this prospective study, conventional magnetic resonance imaging (MRI) with contrast-enhanced T1-weighted images and pCASL were acquired with a 3 T MRI system before surgery in 125 consecutive patients with suspected meningiomas. Finally, the perfusion parameters were collected from 84 grade I and 23 grade II meningiomas. On the pCASL perfusion map, the mean absolute cerebral blood flow (CBF) values from the meningioma (CBFtumour), peritumoural oedema (CBFPTO), white matter of contralateral centrum semi-ovale (CBFwm) and normal grey matter (CBFgm) were calculated. Additionally, the associations of these perfusion parameters with the value of ki-67 index were analysed. The CBFwm value correlated negatively with the largest diameter of the tumour, which limited its usage as a reference for ratio calculation. The CBFtumour values of grade II and grade I meningiomas did not differ significantly: 137.36±71.85 ml/min/100 g versus 123.58±135.80 ml/min/100 g (p=0.641). The CBFPTO value was higher for grade II meningioma as than for grade I meningiomas: 30.30±15.56 ml/min/100 g versus 22.33±9.87 ml/min/100 g (p=0.037). The CBFtumour value was highest in angiomatous meningioma and lowest in fibrous meningioma, thus enabling the differentiation of subtypes of meningioma. The CBFtumour value did not correlate with the ki-67 index of meningioma. The CBFPTO value, rather than the CBFtumour value, from pCASL imaging may serve as a key factor in distinguishing different grades of meningiomas. Moreover, angiomatous meningiomas and fibrous meningiomas can be identified by CBFtumour value.

Angiomatous Meningiomas Have a Very Benign Outcome Despite Frequent Peritumoral Edema at Onset.

Angiomatous meningioma (AM) is a rare subtype of meningioma characterized by highly vascular tumor tissue comprising predominantly variable sized hyalinized blood vessels. The aim of this study is to evaluate the clinical radiologic features of AM and the long-term prognosis in a single neurosurgical center. A total of 93 patients who underwent surgical resection of AMs between 2003 and 2008 were enrolled for analysis. Clinical information, treatment, and radiologic images were collected and analyzed; follow-up was carried out as well. Expression of estrogen receptor, progesterone receptor, and vascular endothelial growth factor was analyzed by immunohistochemistry. Forty-eight females and 45 males were identified. Forty-four patients (47.31%) manifested as hypersignal in T1-weighted imaging sequences and 68 (73.12%) as hypersignal in T2-weighted imaging, and a characteristic ringlike signal was observed in 28 patients (30.11%). Eighty-one cases (87.10%) showed different degrees of peritumor brain edema and it was significantly correlated with the vascular endothelial growth factor expression (P< 0.001). Simpson I resection was achieved in 63 patients (67.74%), grade II in 27 patients (29.03%), and grade III in 3 patients (3.23%). The extent of resection was not associated with the postoperative neurologic function (P= 0.546). Only 4 patients experienced recurrences during the follow-up and these 4 patients were stable until the last follow-up. AMs were a special subtype of meningioma with distinctive radiologic features. AMs manifest benign behavior with a satisfying outcome, which makes Simpson grade II resection an option.

Rare Case of Young Patient with Intraventricular Angiomatous Meningioma

AbstractPediatric meningiomas are rare and account for only 2.2% of the central nervous system (CNS) tumors. In this age group, they are more frequently located in atypical sites, such as, mainly, the ventricular system, with a frequency of 8.8 to 13.6%. Adding this to the fact that the angiomatous subtype constitutes only 2.1% of all meningiomas, the rarity of the case reported here is corroborated. We report a 17-year-old female patient diagnosed with intraventricular angiomatous meningioma; she underwent surgical resection of the tumor in the body and frontal horn of the right lateral ventricle, and there were no neurological sequelae. With a follow-up of 26 months, there was no recurrence and the patient had clinical stability. Intraventricular tumors usually have slow growth and reach a considerable size until they cause symptoms and then are diagnosed. In addition, the deep location of the tumor and its proximity to eloquent areas make these tumors a neurosurgical challenge. The angiomatous subtype, due to the presence of hypervascularization (consisting of &gt; 50% of vascular components), may, in some cases, hinder surgical resection as well as be erroneously diagnosed. However, surgical treatment aimed at total resection of the lesion remains the conduct of choice in the case reported here, especially in patients in the first two decades of life, in which the use of radiation is avoided. Specifically when it comes to the surgery, we chose a transcalosal approach that allows a good transoperative visualization of the lesion when located in the body and frontal horn of the lateral ventricle.

Evaluation parameters between intra-voxel incoherent motion and diffusion-weighted imaging in grading and differentiating histological subtypes of meningioma: A prospective pilot study

PurposeTo prospectively evaluate the usage of intra-voxel incoherent motion (IVIM) magnetic resonance imaging (MRI) parameters in grading and differentiating histological subtypes of meningiomas and in comparing their ability with the traditional diffusion-weighted imaging (DWI) parameter (apparent diffusion coefficient, ADC). MethodsIn this prospective study, 102 participants underwent IVIM MRI and DWI. Traditional DWI and IVIM MRI were performed by using 2 b values (0, 1000s/mm2) and 12 b values (0–3500s/mm2), respectively. Finally, the values of ADC and IVIM parameters were collected from 72 Grade I and 11 Grade II meningiomas. ResultsThe mean ADC values of Grade II and Grade I meningiomas were 0.909±0.268×10−3mm2/s and 0.905±0.194×10−3mm2/s, respectively, p=0.967. The D values were lower in Grade II meningiomas than in Grade I meningiomas (0.459±0.072×10−3mm2/s vs. 0.524±0.030×10−3mm2/s, respectively, p=0.005). In ROC curves, the cut-off D value that separated Grade II meningiomas from Grade I meningiomas was 0.479×10−3mm2/s with a sensitivity of 90.9% and a specificity of 76.7%. The secretory and angiomatous meningiomas had higher IVIM parameters than the other subtypes (all p<0.05). D* was significantly lower in fibrous meningiomas than in other meningiomas (2.783±1.179×10−3mm2/s vs. 5.125±1.918×10−3mm2/s, p<0.001). D, rD and rf values correlated negatively with Ki-67 index while D* and rD* value had positive relation with Ki-67 values. ConclusionIVIM MRI is a promising technique for distinguishing different grades of meningiomas. Different subtypes of meningiomas have different IVIM features, which may help to treatment decision and prognosis evaluation.

Six different extremely calcified lesions of the brain: brain stones.

BackgroundThis study aimed to extend clinical documentation of cerebral calculi by reporting six cases of cerebral calculi with distinct etiologies and localizations. MethodsWe evaluated the age, sex distribution, presenting symptoms, neurological examination findings, pathology results, and location of the calcifications of six patients with intracranial calcifications.ResultsThree of the six patients with brain stones were female (50%), and three were male (50%). The patient ages ranged from 12 to 46 years. A radiological examination of each patient’s cranium was performed with pre-operative cranial computed tomography and magnetic resonance imaging. All of the lesions were completely excised. The patients’ pathologies were determined to be distinct hyalinization, dystrophic calcification, hamartoma, ossification developing from widespread pituitary adenoma tissue, benign mesenchymal neoplasia, a mass consisting of sporadically ossified fibrous tissue, and angiomatous meningioma with distinct hyalinization and fibrosis.ConclusionsIntracranial calcifications are a common phenomenon in neurosurgical practice. However, brain stones, as well as solid calcifications also termed cerebral calculi, are rarely encountered. Brain stones can be classified on the basis of their etiology and localization. Additionally, we suggest that lesions smaller than 1 cm might be classified as calcifications and those greater than 1 cm as brain stones. We further suggest that the differentiation between calcification and brain stones might be based on size. These pathologies typically manifest as seizures and are occasionally identified during routine brain tomography. Meningiomas constitute an important portion of extra-axial calcifications, whereas tumorous and vascular causes are more prevalent among intra-axial calcifications.

The magnetic resonance imaging findings and pathological features of angiomatous meningioma

Objective To study and summarize the magnetic resonance imaging (MRI) findings and pathological features of angiomatous meningioma (AM) for improving the accuracy of the preoperative diagnosis. Methods The clinical characteristics, MRI findings, intraoperative findings and pathological features of 18 patients with AM diagnosed by histopathology were retrospectively analyzed. The clinical presentations, MRI appearances, pathological and immunohistochemistry features of AM were also evaluated. Results There were 18 cases in total, including 13 supratentorial tumors and 5 infratentorial cases; 3 cases beside cerebral falx, 7 cases convexity, 3 cases cerebellum, 2 cases cerebellopontine angle area, 2 cases sellar and 1 case sphenoid ridge. Most lesions were oval in shape. 13 cases showed significant peritumoral edema. Signal-void vessels could be found within or around the tumor in 14 cases. 5 tumors had necrosis and cystic areas. Most AM presented significant heterogeneous enhancement and 16 cases showed wide attachment, including 15 cases of dural tail sign. All tumors underwent complete resection. 7 cases were sent to conduct immunohistochemical examination, including 6 cases CD34+, 7 cases CD31+, 6 cases EMA+, 6 cases Vim+, 7 cases S-100-, 6 cases GFAP-. Proliferating cell nuclear antigen Ki-67 expression was <10 % in all 7 cases. Conclusion AM has some MRI features, which can improve accuracy of preoperative diagnosis, but it still needs to be confirmed by pathology and immunohistochemistry. Key words: Angiomatous meningioma; Magnetic resonance imaging; Pathology; Immunohistochemistry

Clinical value of MRI features predicting hemangiopericytoma and angiomatous meningioma

Objective To investigate the clinical value of preoperative MRI features for predicting hemangiopericytoma (HPC) and angiomatous meningioma. Methods From January 2005 to December 2014, 12 patients with HPC and 17 with angiomatous meningioma admitted to the Department of Neurosurgery, Nanfang Hospital, Southern Medical University were analyzed retrospectively, and pathological diagnosis was conducted according to the WHO 2007 grading criteria. Preoperative MRI parameters included tumor location, tumor size, tumor shape, T1-weighted imaging, T2-weighted imaging, T1-enhanced imaging, apparent diffusion coefficient (ADC) value, fluid-attenuated inversion recovery (FLAIR) imaging, peritumoral edema, dural tail sign, vascular flow void shadow, subarachnoid space in T2-weighted imaging, and tumor hemorrhage or necrosis. The relationship between the two types of tumor imaging features and clinical pathology were detected by using univariate analysis. Logistic regression model was used to evaluate the relationship between these parameters and HPC. Results The results of univariate analysis showed that there were significant differences between age, gender, ADC value, tumor necrosis of two types of tumors and T1-enhanced imaging (P<0.05). Logistic regression model demonstrated that the ADC value was the only independent predictor of HPC (P=0.039, OR: 14.5, 95%CI: 3.7-38.6). Conclusions ADC value can be used as a simple and effective tool to identify primary intracranial HPC and angiomatous meningioma. The possibility of HPC in patients with preoperative DWI hypointensity and high ADC coefficient is greater Key words: Central nervous system neoplasms; Hemangiopericytoma; Meningioma; Magnetic resonance imaging; Apparent diffusion coefficient

Clinical and Radiological Characteristics of Angiomatous Meningiomas.

BackgroundAngiomatous meningioma is a rare histological subtype of meningioma. Therefore, this specific medical condition is rarely reviewed in the literature. In the present work, we report the clinical and radiological features with postoperative outcomes of angiomatous meningioma.MethodsThis retrospective study included the patients who were pathologically diagnosed with angiomatous meningioma after surgical resection between February 2010 and September 2015 in our institute. We analyzed the clinical data, radiological manifestation, treatment and prognosis of all patients.ResultsThe 15 patients (5 males and 10 females) were diagnosed with angiomatous meningioma during the study period. The median age of patients at the time of surgery was 63 years (range: 40 to 80 years). According to Simpson classification, 7, 5, and 3 patients achieved Simpson grade I, II, and IV resection, respectively. In the follow-up period, recurrence was noted in one patient. Ten out of the 15 patients showed homogeneous enhancement. Two patients demonstrated cystic changes. There was no occurrence of calcification or hemorrhage in our patients. Characteristically, 14 out of 15 patients showed signal voids of vessels. Significant peritumoral edema was observed in the majority of tumors (67%).ConclusionAngiomatous meningiomas are rare benign meningioma. Brain images of angiomatous meningioma usually demonstrate signal void signs and peritumoral edema. In the present study, angiomatous meningiomas showed good prognosis after surgical resection.

Histopathological and Immunohistochemical Evaluation of Meningiomas with Reference to Proliferative Markers p53 and Ki-67.

Meningiomas are slow growing primary central nervous system (CNS) tumours attached to the duramater, which arise from the meningothelial cells of the arachnoid. Grading of meningioma based on histological findings assisted with supplementary immunohistochemical studies, predicts the prognosis of meningioma with good precision. To evaluate proliferative markers and correlate with various histological subtypes and grade. A total of 224 meningiomas, diagnosed between January1995 and October 2011were graded according to WHO 2007 criteria. Immunostaining for p53 and Ki-67 markers were performed on 100 cases. There was female predominance. There were 194 Grade I, 24 Grade II and 6 Grade III meningiomas. Brain invasion noted in 18(8%) meningiomas predominantly in grade III followed by grade II. Recurrence was seen in 7 (3.1%) cases, most common in psammomatous followed by angiomatous meningioma. Immunostaining showed p53 positivity in 72.5% of grade I, 83.3% of grade II and all the cases of grade III tumours. Ki-67 Labelling Index (LI) consistently increased from grade I to grade III tumours. p53 and Ki-67 LI correlated well with increasing histological grade and biological behaviour of meningioma.

Epidural angiomatous meningioma of the thoracic spine: A case report.

Spinal epidural angiomatous meningiomas (AMs) are extremely rare lesions. Here, we report on a case of an epidural AM of the thoracic spine with chronic but severe cord compression. The patient underwent a T6-T8 laminectomy through the posterior approach. En bloc resection was achieved, and histopathological examination demonstrated an AM. Delayed paraplegia occurred 4 h postoperatively. The patient was treated with methylprednisolone, hyperbaric oxygen and rehabilitation. Gradually, over the next six months, the bilateral leg strength was improved compared with the preoperative status, and no tumor recurrence was noted. Although epidural AM is extremely rare, it should be included in the differential diagnosis of spinal epidural lesions. A definitive diagnosis is difficult based on magnetic resonance imaging alone due to the nonspecific characteristics of the tumor. Since AM is a histologically benign and highly vascularized tumor, timely gross total resection (GTR) is the most effective treatment. A good clinical outcome may be expected following GTR (Simpson grade I and II resection).

Preoperative radiologic characters to predict hemangiopericytoma from angiomatous meningioma

BackgroundHemangiopericytoma is clinically difficult to be differentiated from angiomatous meningioma. We set out to determine if the preoperative MRI parameters can predict HPC from angiomatous meningioma. MethodsA retrospective review of medical records was conducted for12 HPC patients and 17 angiomatous meningiomas. WHO-2007 grading was used for histopathological diagnosis. Preoperative radiologic parameters included tumor location, tumor size, tumor shape, T1-weighted signal, T2-weighted signal, T1-weighted Gd-enhanced image, ADC value, Flair signal, peritumoral edema (PTE), dural tail sign (DTS), vessel voids sign, arachnoid layer on T2-weighted MRI, tumor hemorrhage and necrosis were analyzed. Univariate analyses were conducted to examine the association between radiological or clinical and histopathological features. Binary logistic regression model was used to evaluate if the parameters predict the occurrence of HPC. ResultsFive parameters, included age, gender, ADC value, necrosis and T1 enhancement was found significantly different between two types after univariate analyses. Binary logistic regression model demonstrated ADC value was the sole independent predictor of HPC (p=0.039, OR: 14.5, CI—3.7–38.6). ConclusionsADC value may be used as a simple and useful optional tool in differentiating primary intracranial HPC from angiomatous meningioma. The combination of ADC value with the data acquired from pre and post-contrast MR scans may further help improve the reliability in the differential diagnosis.

Angiomatous meningioma in Sturge–Weber syndrome

We report a case of an intraventricular angiomatous meningioma arising in a 3-year-old boy diagnosed with Sturge–Weber syndrome (SWS) who presented with intractable epilepsy and right-sided hemiparesis. He underwent surgical resection of the epileptogenic focus. Histologic sections showed the typical findings of SWS accompanied by adjacent mild focal cortical dysplasia (International League Against Epilepsy Type Ib pattern; Palmini et al. Type IA). A small intraventricular mass, which was incidentally noted on imaging studies, was also excised. The mass showed a prominent venous vasculature with intermixed meningothelial cells, consistent with an angiomatous meningioma World Health Organization Grade I. SWS is a rare, sporadically occurring disorder marked by a port wine stain (hemangioma of the skin) arising in the distribution of the trigeminal nerve accompanied by an angiomatous proliferation in the leptomeninges. The underlying cortex often shows prominent dystrophic mineralization and gliosis. Patients often present with seizures and may require surgical resection when seizures prove to be pharmacoresistant. Meningiomas in SWS are a rare occurrence (only one known previously reported case) and angiomatous meningioma in SWS has never been described. The literature is briefly reviewed and the pathogenesis of hemangiomas in SWS and its implication in angiomatous meningioma is discussed.

Surgical treatment of intraspinal angiomatous meningiomas from a single center.

Intraspinal angiomatous meningiomas (AMs) are rare lesions, and no case series have been reported. We retrospectively reviewed the data of 12 patients with intraspinal AMs. All patients underwent magnetic resonance imaging (MRI) of the spine. Computed tomography angiography was performed for three cases with cervical lesion. The series included six females and six males with a mean age of 49.6 years. Five tumors were located in the cervical, one in the cervicothoracic, five in the thoracic, and one in the thoracolumbar spine. The most common symptom was motor deficits and the mean duration of symptoms was 18 months. All patients were treated surgically with gross total resection (GTR) (Simpson grade I and II resection). No patients underwent embolization. After surgery immediately, the neurological function was improved in five patients, remained stable in six patients, and was deteriorated in one patient. During an average follow up of 78.6 months, 11 patients experienced an improvement in the neurological function and one patient maintained preoperative status. No tumor recurrence was observed on MRI. Compared to conventional meningiomas, AMs have no special clinical and radiological features. The accurate diagnosis depends on pathology. Timely GTR (en bloc resection) is the best treatment and embolization is not necessary for most patients. Radiotherapy is not recommended after GTR (Simpson grade I and II resection), and the risk of tumor recurrence is low.

Pseudo-continuous arterial spin labeling reflects vascular density and differentiates angiomatous meningiomas from non-angiomatous meningiomas.

Pseudo-continuous arterial spin labeling (PCASL) can measure tumor blood flow (TBF) reliably. We investigated meningioma TBF using PCASL and assessed for any correlation with histopathological microvascular density (MVD) and the World Health Organization (WHO) classification. Conventional MRI with contrast T1-weighted images and PCASL were acquired with a 3 T scanner before surgery in 25 consecutive patients with meningiomas. Using the PCASL perfusion map, the mean and maximum TBF were calculated from regions of interest placed in the largest cross-sectional plane of each tumor. Tissue sections from 16 patients were stained with CD31 to evaluate MVD and were assigned a WHO classification. The TBFs were statistically compared with MVD and the histopathological meningioma subtypes. There were 16 meningothelial meningiomas, four angiomatous meningiomas, two fibrous meningiomas, one transitional meningioma, and two atypical meningiomas. We observed significant correlation between MVD and both mean and maximum TBF (p < 0.05). The mean and maximum TBF ((mean)TBF, (max)TBF) in angiomatous meningiomas are significantly higher than that in non-angiomatous meningiomas (p < 0.05). PCASL is useful in assessing meningioma vascularity, and in differentiating angiomatous meningiomas from non-angiomatous meningiomas.

Angiomatous meningiomas have a distinct genetic profile with multiple chromosomal polysomies including polysomy of chromosome 5.

Meningiomas are a diverse group of tumors with a broad spectrum of histologic features. There are over 12 variants of meningioma, whose genetic features are just beginning to be described. Angiomatous meningioma is a World Health Organization (WHO) meningioma variant with a predominance of blood vessels. They are uncommon and confirming the histopathologic classification can be challenging. Given a lack of biomarkers that define the angiomatous subtype and limited understanding of the genetic changes underlying its tumorigenesis, we compared the genomic characteristics of angiomatous meningioma to more common meningioma subtypes. While typical grade I meningiomas demonstrate monosomy of chromosome 22 or lack copy number aberrations, 13 of 14 cases of angiomatous meningioma demonstrated a distinct copy number profile--polysomies of at least one chromosome, but often of many, especially in chromosomes 5, 13, and 20. WHO grade II atypical meningiomas with angiomatous features have both polysomies and genetic aberrations characteristic of other atypical meningiomas. Sequencing of over 560 cancer-relevant genes in 16 cases of angiomatous meningioma showed that these tumors lack common mutations found in other variants of meningioma. Our study demonstrates that angiomatous meningiomas have distinct genomic features that may be clinically useful for their diagnosis.

P06.10 * MAST CELL CONTENT IN ANGIOMATOUS MENINGIOMA IN COMPARISON WITH OTHER MENINGIOMA SUBTYPES

We report here that angiomatous meningioma exhibit elevated numbers of mast cells within their tissue architecture compared to most other meningioma subgroups, but similar to the so-called secretory variety of this tumour type. This finding might help to understand the development of the vascular component of this neoplasm and might equally be helpful in diagnosing such tumours, since diagnostic criteria are by no means clear: The (WHO-) definition of the entity states, that angiomatous meningioma is a tumour that exhibits numerous blood vessels on the background of a typical meningioma. But the quantitative aspect i.e. the percentage of vasculature required for this diagnosis is not specified. Our analysis of 27 angiomatous meningiomas revealed a mast cell density of 0.32 % of all tumour cells. This is a significant increase (α = 0.05, U-test) compared to an unselected sample of meningiomas of various, mostly endotheliomatous specimens (0.13 %). This finding relates angiomatous meningiomas to the similarly highly vascular secretory variant, that presents with an even higher percentage of mast cells (1.11 %). This latter subgroup, however, is well defined by the occurrence of secretory products, whereas angiomatous meningioma in other and our samples present with at least two morphological types, microvascular and macrovascular. Single cases of angiomatous as well as secretory meningiomas may therefore produce abundant intracranial edema. The microvascular subtype of angiomatous meningioma is very similar to the so-called mircrocystic variety of meningeal tumors. Thus, the similarity between both on one side (general morphology) as well as the common occurrence of mast cells, prominent vasculature and increased edema formation in angiomatous and secretory meningiomas raises the question of the rationale of meningioma subtyping. In this respect, descriptive morphological analysis may yield significant results.

Comparison of ADC values of intracranial hemangiopericytomas and angiomatous and anaplastic meningiomas

This study aimed to determine whether the use of apparent diffusion coefficient (ADC) values can improve the diagnostic efficacy of magnetic resonance imaging (MRI) to differentiate hemangiopericytoma (HPC) from angiomatous and anaplastic meningioma. Preoperative diffusion-weighted imaging (DWI) studies of 38 patients with pathologically proven intracranial HPC (n = 12) and angiomatous (n = 13) or anaplastic meningioma (n = 13) were retrospectively reviewed. ADC values were measured in the tumor parenchyma and peritumoral edema, and used to obtain normalized ADC (NADC) ratios (ADC of tumor/ADC of normal white matter). Mean ADC values were significantly different between HPC and anaplastic meningioma (1.17 ± 0.30 × 10(-3) mm(2)/s and 0.75 ± 0.11 × 10(-3) mm(2)/s, respectively). Mean NADC ratios were also significantly lower in the malignant cases (0.95 ± 0.13) compared with the benign HPCs (1.53 ± 0.39; P < 0.05). Mean ADC values and NADC ratios did not differ significantly between angiomatous meningioma and HPC (P > 0.05), whereas mean ADC values and NADC ratios were lower for anaplastic meningioma than for either angiomatous meningioma or HPC (P < 0.05). Mean ADC value in peritumoral edema in HPC (1.48 ± 0.11 × 10(-3) mm(2)/s) was lower than in either angiomatous (1.73 ± 0.28 × 10(-3) mm(2)/s) or anaplastic (1.72 ± 0.25 × 10(-3) mm(2)/s) meningioma (P < 0.05), and there was no significant difference between ADC values in anaplastic versus angiomatous meningioma (P > 0.05). ADC values in tumor parenchyma and peritumoral edema can provide helpful information that is otherwise not available from conventional MRI to differentiate HPC from angiomatous and anaplastic meningioma.