Investigation of blood flow in meningothelial and fibrous meningiomas by xenon-enhanced CT scanning

Abstract

We investigated whether xenon-enhanced computed tomography was able to separate meningothelial meningioma from fibrous meningioma. Cerebral blood flow was studied by xenon-enhanced computed tomography in six patients with incidentally detected intracranial meningiomas. All of the tumors were small (<32mm) and there was little or no péritumoral edema. Three patients had meningothelial meningioma and three patients had fibrous meningioma. The tumor blood flow and the contralateral tissue blood flow were determined. The ratio of these parameters was 7.753 ± 0.467 for meningothelial meningiomas and 0.809±0.105 for fibrous meningiomas, with a significant difference between the two tumor subtypes (p = 0.0185). There was no correlation between the signal intensity on magnetic resonance imaging and tumor subtype, and the findings on cerebral angiography also did not indicate the subtype. In conclusion, xenon-enhanced computed tomography showed a difference between smaller meningothelial and fibrous meningiomas in patients with normal surrounding brain tissue. We could not confirm that xenon-enhanced computed tomography was able to distinguish the subtype of meningioma because of the small number of subjects in this study, but our findings might expand interest in the clinical use of this method. [Neurol Res 2000; 22: 615-619]     

Invasive meningioma is associated with a low expression of E-cadherin and beta-catenin

Invasive meningioma shows benign histological features (WHO grade 1) and the brain expansion at the tumor-brain interface, and recurs more frequently than common meningiomas. To determine the mechanism of brain expansion, we studied the relationship between invasive meningioma and cell adhesion molecules. Immunostaining for E-cadherin (E-CH), N-cadherin (N-CH), beta-catenin, and Ki-67 was performed in 103 meningiomas that consisted of 61 meningothelial meningiomas, 25 fibrous meningiomas, 12 invasive meningiomas and 5 anaplastic meningiomas. All tumors were negative for N-CH. All the 61 meningothelial meningiomas, 10 of 12 invasive meningiomas, and 3 of 5 anaplastic meningiomas were positive for both E-CH and beta-catenin, while these were both negative in all of the fibrous meningiomas. In invasive meningiomas, the expansive part of the tumor showed a lower rate (4/12 tumors) of E-CH and beta-catenin positivity, while the central part showed a higher rate (10/12 tumors). The Ki-67 labeling index was higher in invasive and anaplastic meningiomas than in meningothelial meningiomas. These results suggest that a reduction in cell adhesion molecules and increased proliferative activity may be related, which may lead to a better understanding of the mechanism of meningioma expansion in the future.     

Assessment of hemodynamics of meningioma with dynamic MR imaging]

Dynamic MR imaging provides hemodynamic information about normal and pathologic tissue of the brain. The purpose of our study was to evaluate the usefulness of dynamic MR imaging in the assessment of tumor vascularity and the tumor tissue blood flow of meningiomas. We studied 13 patients with meningiomas using dynamic spin-echo MR imaging. The histological subtypes of meningioma were confirmed by the examination of surgical specimens in all patients, and tumors were meningothelial in 9 cases, fibrous in 2, transitional in 1, and psammomatous in 1. Serial images were obtained every 18-24 sec for 8 minutes and 30 seconds after rapid injection of gadolinium diethylenetriaminepentaacetic acid. Different parameters (time to peak, maximum of signal intensity and the washout ratio) were calculated directly from signal intensity curves. As an indicator of tumor vascularity, microvessel density was counted based on immunohistochemically stained sections and tumor tissue blood flow was measured using an xenon-CT system. The maximum of signal intensity corresponded to the tumor vascularity. With dynamic MR imaging, the time intensity curves (TI curves) were divided into two patterns; type 1 had a steep increase with a peak and type 2 had a slow increase to a peak followed by plateau. The maximum of signal intensity measured from TI curve of dynamic MR imaging correlated significantly with microvessel density (R2 = 0.840, p < 0.0001). Linear regression revealed a significant positive relation between the washout ratio and the tumor tissue blood flow in group showed type 1 on TI curve (R2 = 0.961, p < 0.001). There was also a significant negative correlation between the time to peak and the tumor tissue blood flow (R2 = 0.792, p < 0.01). We suggest that dynamic MR imaging is useful for evaluating hemodynamics of meningiomas.     

Sclerosing meningioma: immunohistochemical analysis of five cases

Sclerosing meningioma is a rare morphologic subtype of meningioma and may be mistaken for atypical or malignant meningioma and astrocytoma or schwannoma because of marked collagen deposits and a sparse population of cells with little resemblance to meningothelial cells. Authors describe the histopathologic and immunophenotypic features of five cases of sclerosing meningioma. Histologically, all the cases consisted of paucicellular collagenous tissue containing spindle cells with or without small foci of meningothelial cell proliferation. The morphology and immunohistochemical profile of the spindle cells were different from those of conventional meningothelial cells. The meningothelial cells showed a typical immunoreactivity of conventional meningiomas, while the spindle cells displayed a strong expression of vimentin. The Ki-67 labelling index was uniformly low in all cases, and none of cases expressed p53 protein. In summary, the recognition of meningothelial cells in massively sclerotic lesions is helpful for a correct diagnosis. In the cases with a total absence of meningothelial cells, however, the vague collagenous whorls are more diagnostic rather than immunohistochemistry. Considering association with clear cell meningioma, prospective and retrospective long-term follow-up is necessary for deciding whether reminiscent clear cell meningiomas should be separated from sclerosing meningioma or not.     

Cytoplasmic iron deposition is associated with the expression of oxidative DNA damage marker in meningiomas

Angiomatous meningiomas are rare meningioma subtypes, which are characterized by abundant, well‐formed vessels. We encountered two cases of newly diagnosed angiomatous meningiomas exhibiting tumor cells with brown pigments, which were histochemically proven to be iron. In an attempt to understand its pathological significance, we assessed this unusual finding in representatives for each grade of meningiomas and immunoexpression of transferrin receptor (CD71) and the oxidative DNA damage marker, 8‐hydroxy‐2′‐deoxyguanosine (8‐OHdG). Iron deposition in the tumor cells was observed in 8/15 (53%) angiomatous meningioma cases, 2/6 (33%) microcystic meningiomas and 2/20 (10%) meningothelial meningiomas, which included clustered microvessels, but not in fibrous, atypical or anaplastic meningiomas (P = 0.001). Cytoplasmic CD71 expression was largely negative in angiomatous meningioma cases, but positive in meningothelial and high‐grade meningiomas, suggesting that the transferrin‐dependent iron transporter was involved in iron uptake in meningiomas. Nuclear expression of 8‐OHdG was observed in ≥50% of the tumor cells in all 15 cases of angiomatous meningioma and was associated with the presence of regressive histopathological findings, such as hyalinized vessels and cystic changes. In addition, the fraction of iron‐containing tumor cells was correlated to those expressing 8‐OHdG (P = 0.005). Our finding indicates that cytoplasmic iron deposition in tumor cells is characteristic of highly vascularized benign meningiomas and related to increased oxidative DNA damage markers.     

Microcystic meningiomas: comparison of histology and computed tomography

INTRODUCTION: Microcystic meningiomas are defined by large vacuolated and stellate shaped cells. We recently examined a microcystic meningioma mimicking a malignant tumor on computed tomography (CT). The aim of the current study was to compare the radiological features of microcystic meningiomas with their histological patterns. METHODS: We have diagnosed 7 intracranial microcystic meningiomas among 204 meningiomas registered in the files of our Department of Pathology from 1994 to 2001. All CT scans performed before surgery were reviewed. RESULTS: Three of the microcystic meningiomas appeared as entirely microcystic tumors. Two of them were homogeneously hypodense or isodense on CT scan. The third mening was heterogeneous, containing some blood. The histologic pattern of the 4 other meningiomas showed microcystic tumor cells associated with meningothelial or fibrous tumor cells. These meningiomas were heterogeneous on CT scan. All meningiomas seemed to be connected to the dura mater. Three tumors were strongly and homogeneously enhanced after contrast media injection while 3 others were heterogeneously enhanced. No enhanced CT scan was available for 1 case. Astrocytomas were incorrectly diagnosed by CT scan in the 3 heterogeneously enhanced tumors. Meningiomas were correctly diagnosed in the 3 strongly enhanced tumors. CONCLUSION: The presence of microcystic tumour cells in meningiomas often results in erroneous diagnosis on CT scan, particularly for those which are heterogeneously enhanced. In these cases, a diagnosis of astrocytoma is often made.     

脑膜瘤全切除术后复发的组织病理学因素分析

目的 通过对患者的年龄、性别、脑膜瘤组织学分型及分级等因素的分析,了解它们与肿瘤复发间的关系.方法 56例脑膜瘤标本分为复发组(n=30)、初发组(n=26),对全部病理标本进行组织学分级,统计学分析组织学分级与肿瘤复发之间的关系.结果 复发组上皮型17例(56.67%),纤维型7例(23.33%),两型比较,P＜0.05.复发组组织病理学分级Ⅱ级、Ⅲ级者比率显著高于初发组(P＜0.01).患者的年龄、性别2组对比差异无统计学意义(P＞0.05).结论 脑膜瘤复发在组织病理学分型上以上皮型居多,脑膜瘤组织学分级越高复发率越高.     

The characterization of human brain tumor using magnetization transfer technique in magnetic resonance imaging.

The clinical applicability of magnetization transfer (MT) technique in magnetic resonance imaging (MRI) for the estimation of the histological and constitutional feature of brain tumors was investigated. MT effect was evaluated by measuring the MT ratio (MTR). The parameters in 1.5-tesla MRI system were as follows: TR, 50 msec; TE, 5 msec; flip angle, 30 degree; offset frequency of off-resonance MT pulse, 1000 Hz. The sequence was performed in 20 normal volunteers and 45 patients with brain tumors which were characterized histologically and surgically. The MTR for brain tumors was significantly lower than that for normal brain tissue (p < 0.05). The MTR for meningioma was higher than that for the other brain tumors (p < 0.05). In the meningiomas, MTR for fibrous type was higher than that for meningothelial type, but there was no statistical significance. Regarding the physical consistency for the brain tumors, as classified by surgery, there was a statistically significant difference in MTR between the soft tumor group (0.22 +/- 0.03, n = 6) and the hard tumor group (0.36 +/- 0.04, n = 10) (p < 0.01). This study suggested that the MT technique for patients with brain tumor may be useful to understand the characteristics of the tumors presurgically, based on the degree of intermolecular interaction of macromolecule such as protein.     

Meningioma with the unique coexistence of secretory and lipomatous components: a case report with immunohistochemical and ultrastructural study

Meningiomas exhibit a broad spectrum of differentiation potency corresponding to different histological subtypes. The separate secretory or lipomatous transformation of meningothelial cells is uncommonly encountered in meningiomas classified into distinct secretory or lipomatous variants. The coexistence of these two different histological subtypes is extremely rare. We report an exceptional case of secretory meningioma associated with extensive lipomatous component in a 58-year-old woman. CT scan and MRI of the brain showed a well-defined tumor mass in the right temporal lobe with areas of adipose tissue and extensive surrounding brain edema. Microscopically, the tumor was composed of two components: whorls of meningothelial cells with numerous PAS-positive hyaline inclusions (pseudopsammoma bodies) and numerous mature adipocyte-like cells. The presence of neutral fat was confirmed by oil-red-O staining. The hyaline inclusions and tumor cells surrounding them showed strong immunoreactivity for EMA and CEA. Ultrastructural findings confirmed both secretory and lipomatous differentiation of tumor cells. The majority of lipidized neoplastic cells shared the features of meningothelial cells and adipocytes. Our result supports the opinion that lipomatous component ought to be considered as an advanced lipidization of neoplastic meningothelial cells rather than true metaplastic transformation of meningothelial cells into mature fat tissue. The present case of meningioma demonstrates a unique coexistence of secretory and lipomatous meningothelial components, reflecting the multipotency of phenotypic transformation of primary meningothelial cells.     

Expression of c-Myc, neurofibromatosis Type 2, somatostatin receptor 2 and erb-B2 in human meningiomas: relation to grades or histotypes

Meningiomas, which originate from arachnoid cells, represent one of the largest subgroups of intracranial tumors. They are generally benign, but can progress to malignancy. The aim of our study was to determine the expression of 4 genes, c-Myc, neurofibromatosis Type 2 (NF2), somatostatin receptor isoform 2 (sst2) and erb-B2, that have been associated with tumorogenesis or, possibly, with aggressive behavior or recurrence of meningiomas. We measured levels of mRNAs coding for these genes by qRT-PCR in 51 cases and levels ofc-Myc protooncogene and sst2 protein by immunohistochemistry in 26 cases of meningiomas of various grades and histotypes. C-Myc mRNA and protein levels were not grade-related, but validated subdivision of the 36 benign meningiomas into two groups, Groups IA and IB, based on histological and clinical features (Ki-67-proliferative index, absence or presence of mitoses, rate of recurrence and incidence of perilesional edema). In addition to histopathological grading, c-Myc expression may be useful in predicting tumor recurrence in patients with low-grade meningiomas. NF2 mRNA levels and sst2 mRNA and receptor levels were not grade-related, but were histotype-related, with significantly higher levels in the meningothelial subtype than in the fibroblastic subtype. Erb-B2 mRNA levels were not grade- or histotype-related. Furthermore, the high expression of sst2 in meningothelial meningioma suggests the possibility of a different tumorigenesis process in this meningioma subtype and may open perspectives for the diagnosis and therapy of this subtype using somatostatin as an antiproliferative agent.     

Extracranially extended meningothelial meningiomas with a high MIB‐1 index: A report of two cases

Meningiomas that extend from the meninges to the extracranial tissue and result in skull osteolysis have been known to take an aggressive clinical course. Two such cases in elderly patients are reported. Case 1 is an 82‐year‐old woman who had undergone removal of the parasagittal meningioma (meningothelial meningioma with 5% of MIB‐1 index) 4 years and 6 months previously, developed recurrence of the tumor that extended to extracranial soft tissue. Biopsy obtained from the subcutaneous tissue showed an atypical meningothelial meningioma with 20% of MIB‐1 index. In case 2 an 84‐year‐old man, who developed rapidly progressing dementia and gait disturbance, the MRI study revealed an intracranial‐extraaxial right frontal tumor with an extracranial extension resulting in skull osteolysis. Pathological examination of the totally resected tumor identified meningothelial meningioma, but MIB‐1 index of the intracranial portion of the tumor was less than 0.1%, while that of the extracranial portion was approximately 15%. Although the meningiomas presently reported failed to show histological features of malignancy, the high MIB‐1 index indicated that they were rapidly growing tumors. In the present report it is considered that meningioma cells that invade the skull and extracranial tissue are biologically aggressive and require total resection, as long as the condition of the patients is feasible for surgery.     

High-dose radiation-induced meningiomas following acute lymphoblastic leukemia in children

The authors review three personal cases of patients who developed cerebral meningiomas following high-dose radiotherapy for acute lymphoblastic leukemia. Two patients were female and one male. Their ages when the leukemia appeared were between 11 and 15 years. All patients were treated with a course of prophylactic irradiation to the neuraxis for a total dose of 24 Gy. After an average interval of 10.4 years, all three patients presented a meningioma; histologically, one was meningothelial and two were fibrous. All three meningiomas presented atypical features. At follow-up 1, 4, and 4 years respectively after surgery, none of these patients presents neurological deficits or neuroradiological signs of recurrence. Forty-nine cases of high-dose radiation-induced meningioma are also reviewed.     

The double immunostaining of CD133 and Ki-67 favours a significant co-localization pattern in fibroblastic subtype of meningiomas

BACKGROUND AND PURPOSE : A unique molecular and/or cellular marker for meningiomas, the most common intracranial tumours, has not been identified yet. MATERIAL AND METHODS: We investigated the co-localization fraction of CD133/Ki-67 in meningioma tissue array slide composed of 80 meningioma tissue samples of various histological variants. CD133 - a cell membrane stem cell marker - was previously proved to be associated with the initiation and progression of intracerebral gliomas and medulloblastomas. RESULTS : Immunohistochemical co-localization of CD133/Ki-67 was significantly higher in fibroblastic variant than in meningothelial and transitional subtypes. However, since there were only 3 atypical and 1 malignant meningioma spots in the tumour tissue array slide, it is difficult to draw a firm conclusion regarding the actual co-localization percentage and persistence of CD133/Ki-67 in atypical and malignant meningiomas. CONCLUSIONS : Far higher co-staining percentage of CD133/ Ki-67 in fibroblastic meningioma samples compared to meningothelial subtype, a histological meningioma variant, architectonically resembling the non-neoplastic meningeal cells, gave us the impression that CD133 may play a role in the formation and progression of fibroblastic meningioma variants. The persistency and the validity of this finding need to be verified by further histopathological and molecular research in order to clarify the possible role of CD133 in meningiogenesis.     

Lipomatous meningioma: a study of five cases with brief review of literature

Lipomatous meningiomas are an uncommon subtype of meningiomas. In the present report, the clinical characteristics, neuroimaing and pathological features of 5 patients (4 males, 1 female; age range, 17-45 years; mean age, 35.2 years) with lipomatous meningioma were analyzed. The neuro-pathological reevaluation of lipomatous meningioma involved assessment of histological features proposed by the current WHO classification. The presence or absence of high whorls, fascicles, solid growth, glial invasion, necrosis and nuclear pleomorphism was assessed. The most common presenting symptom was seizures. Location of tumor was frontal (3 cases), parietal (1 case) and fronto-temporal (1 case). All cases showed radiological features of conventional meningioma. Complete excision of tumor along with involved dura was performed in all the patients. Three tumors were meningothelial and 2 were transitional. Tumoral lipid content was variable from 10% to 30%. In addition, there were microcystic features (2 cases) and psammoma bodies (1 case). No recurrence was noted in any of our cases till the last follow-up. Lipomatous meningioma represents a rare distinctive type of meningioma, with a good prognosis with complete removal.     

脑膜瘤生物学特性与MRI信号特征的相关性研究

目的探讨脑膜瘤手术前MRI信号特征对手术中肿瘤生物学特性的预测价值。方法以WHO 2000年脑膜瘤病理分类为基础，追踪研究85例脑膜瘤患者，寻找肿瘤MRI信号特征与生物学特性，包括供血、质地以及瘤一脑界面是否清楚及其内在联系。结果不同病理亚型的脑膜瘤，表现出不同的MRI信号特征和生物学特性。多数良性脑膜瘤MRI信号均匀、形态规则，肿瘤周围水肿由肿瘤生长部位决定。非典型脑膜瘤MRI信号不均匀、形态不规则，肿瘤周围水肿不明显，间变型脑膜瘤周围水肿则非常明显。血管瘤型、间变型和部分非典型脑膜瘤血供丰富。微囊型、多数上皮型和多数血管瘤型脑膜瘤质地偏软，纤维型、化生型和砂粒体型则质地偏韧、硬。间变型、部分非典型和部分血管瘤型脑膜瘤的瘤一脑界面不清楚。结论脑膜瘤MRI信号特征的分析能为判断其病理亚型和生物学特性提供线索，有助于临床上制定手术策略，提高疗效。     

Intracranial cystic meningiomas: A series of six patients

ObjectiveAlthough meningiomas are the most common primary non-glial intracranial tumors, cystic meningiomas are quite rare. This study presents six cases in order to discuss the radiological and pathological features of cystic meningiomas.Patients and methodsSix patients with cystic meningiomas were included in the study. All patients underwent a cranial computed tomography scan and magnetic resonance imaging (MRI) evaluation, pre- and postoperatively.ResultsAll patients presented with long standing headache dating back at least two years. There was no gender predominance in our series. Radiological evaluation revealed two parasagittal and two convexity meningiomas located at the frontal region. Two lesions were located at the tuberculum sellae and the foramen magnum. All of the tumors were totally excised (Simpson Grade I or II). Pathology results included meningothelial meningioma in three patients, angiomatous meningioma in two patients, and metaplastic meningioma in one patient. In two patients, the cystic meningiomas were resected with the use of sodium fluorescein (Na-Fl) under a YELLOW 560 nm microscope filter. Na-Fl was found to be very useful in demonstrating the brain–tumor interface, and it was especially effective in resecting the cyst wall of the peritumoural cystic meningiomas. None of the patients had any complications, and no recurrences were noted in any of the patients within the mean follow-up period of 51 months (range: 16–102 months).ConclusionIt is important to note MRI changes specific to cystic meningioma and include meningiomas in the differential diagnosis of intracranial cystic lesions. The use of sodium fluorescein (Na-Fl) under a YELLOW 560 nm microscope filter is a useful tool to differentiate the brain-tumor interface, as well as to identify the cyst wall in order to fully resect the tumor with the cystic component to avoid recurrence and achieve better clinical results.     

The origin of intracranial fibrosarcoma

Summary To elucidate the cellular derivation of intracranial fibrosarcoma, specimens from two cases of primary sarcoma and two cases of secondary, radiation-induced sarcoma in the cranium were examined by light and electron microscopy and histochemical techniques. The findings were carefully compared with those in four cases of benign fibroblastic meningioma. All the intracranial sarcomas examined in this study were localized on the cerebral surface and invaded the dura mater and brain.The histology of these tumors closely resembled that of fibrous fibrosarcoma described by Christensen and Lara [2]. The microscopic features of primary sarcomas were characterized by a spoke wheel arrangement of tumor cells, intercellular deposits of variable amounts of collagen fibers and the presence of many xanthoma cells. Secondary sarcomas presented tumor cells arranged in parallel interlacing bundles. An island of tumor tissue with the characteristics of benign meningioma was disclosed in a primary sarcoma. In meningioma was disclosed in a primary sarcoma. In electron micrographs, sarcoma cells showed ultrafine structures characteristic of meningothelial cells, including interdigitated cytoplasmic processes, desmosomes and/or half desmosomes, and abundant intracytoplasmic filaments. Basement membrane or an analogous substance, which is very unusual in the meningioma, were identified in some specimens of our primary sarcomas and fibroblastic meningioma. In the histochemical study, the activities of acid phosphatase and non-specific esterase showed no significant differences between the sarcoma cells and the meningioma cells.On the basis of morphological and histochemical findings, it is concluded in this study that fibrous fibrosarcomas in the cranium are of meningothelial derivation and therefore should be included in the category of malignant meningioma.     

脑膜血管瘤病合并脑膜瘤临床病理及文献复习

目的 探讨脑膜血管瘤病(MA)合并脑膜瘤的临床病理特点.方法 回顾性分析1例颅内MA合并脑膜瘤病人的临床资料,行病理形态学观察及免疫组织化学检测,并对该病进行文献复习.结果 光镜观察:皮质内血管增生,脑膜上皮细胞及梭形的纤维母细胞样细胞围绕血管排列,部分大血管明显胶原化及透明变性,伴钙化或砂砾体形成,且可见明显的过渡型脑膜瘤成分,病灶内残留变性神经元和胶质细胞增生.免疫组化染色显示:vimentin阳性,上皮细胞膜抗原(EMA)局灶性阳性,Ki-67阳性率在脑膜瘤区域约为3％,在脑膜血管瘤病区则＜1％.结论 MA是--种少见的良性病变,病变通常位于大脑额颞叶皮质并可累及周围脑膜组织,MA合并脑膜瘤更少见,在形态学上应与侵袭性脑膜瘤、孤立性纤维瘤、颅内神经鞘膜瘤等鉴别.     

Proliferative potential of meningiomas determined with the monoclonal antibody Ki-67

Summary In 30 meningiomas we investigated the proliferation rate of various subtypes with the monoclonal antibody Ki-67. Frozen sections were incubated with Ki-67 antibody using a modified Alkaline Phosphatase anti-Alkaline Phosphatase (APAAP)-technique and evaluation of proliferation rate was done by cell counting. Meningiomas of the meningiotheliomatous, fibrous and angioblastic subtype without atypical histological findings contained 1% or less proliferating cells. In recurent tumors, in transitional and in anaplastic meningiomas there is a marked increase of proliferating cells up to 20%. The distribution of marked cells varies in recurrent tumors and anaplastic meningiomas, and a focal proliferation of tumor cells was seen in meningiomas from transitional type. Immunohistological labelling of proliferating cells in meningiomas may allow a more precise prediction of the proliferation potential of each meningioma.     

Immunohistochemical expression of progesterone and estrogen receptors in meningiomas

In this study we present results of investigations of progesterone and estrogen receptors in most frequent, WHO grade I histological types of meningiomas (meningothelial, fibrous, and transitional) and in atypical--WHO grade II variant of these tumors. Samples from 64 tumors were examined. The cohort consisted of 46 WHO grade I (21 transitional, 13 fibrous and 12 meningothelial histologic variants) and of 18 atypical meningiomas. Apart from immunohistochemical examination of progesterone and estrogen receptors, MIB 1 labeling index was estimated. Positive immunoreaction for progesterone receptors was found in 100% meningothelial, 95% transitional, 46% fibrous and 78% atypical variant of meningiomas. Intensity of immunoreaction was stronger in grade I than in grade II tumors. Immunoexpression of estrogen receptors was found in 48% of the investigated meningiomas. No correlation was stated between WHO grade I and grade II tumors, and between meningothelial, transitional and fibrous variants of the neoplasms.