Osseous changes in meningioma en plaque

Hyperostosis is the most common skull change associated with meningioma. Five hyperostosis cases of meningioma en plaque infiltrating the skull processed without previous decalcification of the bone tissue were investigated histologically and immunohistochemically with antibodies against somatostatin receptor 2A (SSR2A). Undecalcified bone biopsies embedded in methylmethacrylate and paraffin-embedded extraosseous tumor tissues were analyzed. All five cases were well-differentiated meningotheliomatous meningiomas en plaque according to the WHO classification of tumors and revealed areas of hyperosteoidosis. Furthermore, all five meningiomas en plaque presented strong positive reactions to antibodies against SSR2A in both the intraosseous and extraosseous tumor proliferates. In summary, similar morphological changes characterized by hyperosteoidosis were observed in a small cohort of meningioma en plaque associated with expression of SSR2A and reports in the literature of the histogenesis of hyperostosis in meningioma en plaque are discussed.

¹H-MRS of intracranial meningiomas: what it can add to known clinical and MRI predictors of the histopathological and biological characteristics of the tumor?

OBJECTIVE

The main goal of the present study was evaluation of proton magnetic resonance spectroscopy (¹H-MRS) in diagnosis of histopathologically aggressive intracranial meningiomas.

METHODS

Single-voxel ¹H-MRS of 100 intracranial meningiomas was performed before their surgical resection. Investigated metabolites included mobile lipids, lactate, alanine, N-acetylaspartate (NAA), and choline-containing compounds (Cho). According to criteria of World Health Organization (WHO) 82 meningiomas were assigned histopathological grade I, 11 grade II, and 7 grade III. The MIB-1 index varied from 0% to 27.3% (median, 1.6%). In 43 cases tight adhesion of the tumor to the pia mater or brain tissue was macroscopically identified at surgery. The consistency of 49 meningiomas was characterized as soft, 26 as hard, and 25 as mixed.

RESULTS

No one metabolic parameter had statistically significant association with histopathological grade and subtype, invasive growth, and consistency of meningioma. Univariate statistical analysis revealed greater ¹H-MRS-detected Cho content (P=0.0444) and lower normalized NAA/Cho ratio (P=0.0203) in tumors with MIB-1 index 5% and more. However, both parameters lost their statistical significance during evaluation in the multivariate model along with other clinical and radiological variables. It was revealed that non-benign histopathology of meningioma (WHO grade II/III) is mainly predicted by irregular shape (P=0.0076) and large size (P=0.0316), increased proliferative activity by irregular shape (P=0.0056), and macroscopically invasive growth by prominent peritumoral edema (P=0.0021).

CONCLUSION

While ¹H-MRS may be potentially used for the identification of meningiomas with high proliferative activity, it, seemingly, could not add substantial diagnostic information to other radiological predictors of malignancy in these tumors.

Assessment of Epidermal Growth Factor Receptor (EGFR) expression in human meningioma

PURPOSE

This study explores whether meningioma expresses epidermal growth factor receptor (EGFR) and determines if there is a correlation between the WHO grade of this tumor and the degree of EGFR expression.

METHODS

Following institutional review board approval, 113 meningioma specimens from 89 patients were chosen. Of these, 85 were used for final analysis. After a blinded review, immunohistochemical stains for EGFR were performed. Staining intensity (SI) was scored on a scale 0-3 (from no staining to strong staining). Staining percentage of immunoreactive cells (SP) was scored 1-5 (from the least to the maximum percent of the specimen staining). Immunohistochemical score (IHS) was calculated as the product of SI and SP.

RESULTS

Eighty-five samples of meningioma were classified in accordance with World Health Organization (WHO) criteria: benign 57/85 (67%), atypical 23/85 (27%), and malignant 5/85 (6%). The majority of samples demonstrated a moderate SI for EGFR. IHS for EGFR demonstrated a significant association between SI and histopathologic subtype. Also, there was a correlation between the SP and histopathologic subtype (p = 0.029). A significant association was determined when the benign and the atypical samples were compared to the malignant with respect to the SP (p = 0.009). While there was a range of the IHS for the benign and the atypical histologic subtypes, malignant tumors exhibited the lowest score and were statistically different from the benign and the atypical specimens (p < 0.001).

CONCLUSIONS

To our knowledge, this represents the largest series of meningioma samples analyzed for EGFR expression reported in the literature. EGFR expression is greatest in benign meningiomas and may serve a potential target for therapeutic intervention with selective EGFR inhibitors.

Expression of progestrone receptor and proliferative marker ki 67 in various grades of meningioma

Meningiomas are slow-growing neoplasms which recur locally, their morphologic grading is simple but do not always correlate with patient outcome. The aim of present study is to evaluate the status of progesterone receptor (PR) and proliferation marker Ki67 in various grades of meningioma in a group of Iranian patients. 78 cases of meningioma were selected from the file of a hospital university. All archival H&E stained sections were reviewed and regraded according to WHO criteria. Immunohistochemical analysis for PR and Ki67 was performed on formalin-fixed, paraffin-embedded samples. PR status considered positive if >10% of tumor cell's nuclei were strongly immunoreactive, or if >50% of nuclei were stained with medium intensity. The Ki67 labeling index (LI) is defined as the percentage area with strongest immunostaining. PR were positive in 61/63 (96.8%) of grade I tumors, 2/10 (20%) of grade II, and 0/5 (0%) of grade III tumors. Ki67 LI was %2.98 +/- 2.27 in grade I tumors, %9.30 +/- 5.79 in grade II tumors and %34.00 +/- 5.47 in grade III tumors. For both markers, differences between grade I, II and III tumors were significant (P < 0.001). There was a reverse relationship between mean of Ki67 LI and PR status, with increasing grade of tumor. Evaluation of PR status and Ki67 LI together with conventional histologic evaluation can help in providing more information about the biologic behaviour of meningiomas, especially for those that histological grading is not straightforward.

[Extracranial meningioma: morphological and histogenetical aspects and relations with perineurioma]

The clinicomorphological, immunohistochemical, and ultrastructural characteristics of 11 cases of extracranial meningioma versus 79 soft tissue perineuriomas were studied. There were significant similarities (cell morphology, immunoprofile, ultrastructural features of perineurial differentiation) of both entities. Considering the point of view that arachnoid and perineurial cells are anatomically, embryologically, and functionally related, it is most possible that extracranial meningiomas may be derived from perineurial cells (or their progenitor cell) rather than from displaced arachnoid cells.

Hypermethylation and transcriptional downregulation of the TIMP3 gene is associated with allelic loss on 22q12.3 and malignancy in meningiomas

The gene for the tissue inhibitor of metalloproteinase 3 (TIMP3) on 22q12.3 had been reported to be inactivated by promoter methylation in various types of cancers, with controversial findings in meningiomas. We performed direct sodium bisulfite sequencing in a series of 50 meningiomas, including 27 benign meningiomas [World Health Organization (WHO) grade I], 11 atypical meningiomas (WHO grade II) and 12 anaplastic meningiomas (WHO grade III), and found hypermethylation of TIMP3 in 67% of anaplastic meningiomas, but only 22% of atypical and 17% of benign meningiomas. Moreover, TIMP3 methylation scores were significantly inversely correlated with TIMP3 mRNA expression levels (P = 0.0123), and treatment of the meningioma cell line Ben-Men-1 with demethylating agents induced an increased TIMP3 mRNA expression. TIMP3 is located in the chromosomal band 22q12, the allelic loss of which occurs early in meningioma tumorigenesis and preferentially targets the NF2 tumor suppressor gene. In our tumor panel, all meningiomas with TIMP3 hypermethylation--except for a single case--exhibited allelic losses on 22q12.3. Thus, TIMP3 inactivation by methylation seems fairly exclusive to meningiomas with allelic losses on 22q12 but--in contrast to NF2 mutation--appears to be involved in meningioma progression as it is associated with a more aggressive, high-grade meningioma phenotype.

[Expression of HER2/neu in meningiomas: an immunohistochemistry and fluorescence in situ hybridization study]

OBJECTIVE

To investigate the expression of HER2/neu, Ki-67 and TK1 protein in meningiomas in correlation with tumor grades and recurrence.

METHODS

Twenty cases of each of the following types of meningiomas were selected for the study, namely: the benign non-recurrent, recurrent benign, atypical and malignant, according to the World Health Organization (WHO) histological classification of nervous system, 2007. Immunohistochemistry study for HER2/neu, Ki-67 and TK1 protein was performed. HER2/neu gene amplification was detected using FISH. Cases with HER2 protein overexpression were studied by immunohistochemistry staining. The results of the biomarker assays were also used to study the correlationship with the tumor grades and tumor recurrency.

RESULTS

Immunohistochemistry showed that the positive rates of HER2 expression in non-recurrence benign group, recurrence benign group, atypical group and malignant group were 3 cases (15%), 6 cases (30%), 7 cases (35%), and 10 cases (50%), respectively (P < 0.05). A higher tumor grade was correlated with a higher rate of HER2/neu expression. The Ki-67 and TK1 labeling index (LI) in non-recurrence group were lower than those in the atypical or malignant group (P < 0.05), whereas the atypical group had lower LI than that of the malignant group (P < 0.05). Higher levels of LI of Ki-67 and TK1 were correlated with higher tumor grades and recurrence of the benign meningiomas (P < 0.05). Expression of HER2 was positively correlated with Ki-67 and TK1 (r = 0.445, P < 0.01; r = 0.501, P < 0.01, respectively), and there was a positive correlation between Ki-67 and TK1 (r = 0.450, P < 0.01) as well. HER2/neu gene copy amplification in 7 of 26 cases (26.9%) of HER2 immunopositive meningiomas. The rates of HER2/neu gene amplification were 0 in tumors with 1+ immunopositivity, 4/6 in tumor with 2+ immunopositivity and 3/4 in tumor with 3+ immunopositivity. HER2/neu gene amplification in 3+ and 2+ immunopositive cases had no statistical significance (P > 0.05). Aneuploidy of chromosome 17 existed in 9 of 26 of HER2 immunopositive meningiomas (34.6%). However, the rates of chromosome 17 aneuploidy had no significant difference among tumors with variable HER2/neu imumopositivity (P > 0.05).

CONCLUSIONS

High levels of HER2 and Ki-67 or TK1 expression correlate with the increase of tumor grades and tumor recurrence. HER2/neu gene amplification is seen in a subset of meningiomas with the protein expression (26.9%). A combination of biomarker study including HER2/neu, Ki-67 and TK1 may be useful in predicting the biological behavior of meningiomas.

Maternally expressed gene 3, an imprinted noncoding RNA gene, is associated with meningioma pathogenesis and progression

Meningiomas are common tumors, representing 15% to 25% of all central nervous system tumors. NF2 gene inactivation on chromosome 22 has been shown as an early event in tumorigenesis; however, few factors underlying tumor growth and progression have been identified. The chromosomal abnormalities of 14q32 are often associated with meningioma pathogenesis and progression; therefore, it has been proposed that an as yet unidentified tumor suppressor is present at this locus. Maternally expressed gene 3 (MEG3) is an imprinted gene located at 14q32 which encodes a noncoding RNA with an antiproliferative function. We found that MEG3 mRNA is highly expressed in normal arachnoidal cells. However, MEG3 is not expressed in the majority of human meningiomas or the human meningioma cell lines IOMM-Lee and CH157-MN. There is a strong association between loss of MEG3 expression and tumor grade. Allelic loss at the MEG3 locus is also observed in meningiomas, with increasing prevalence in higher grade tumors. In addition, there is an increase in CpG methylation within the promoter and the imprinting control region of MEG3 gene in meningiomas. Functionally, MEG3 suppresses DNA synthesis in both IOMM-Lee and CH157-MN cells by approximately 60% in bromodeoxyuridine incorporation assays. Colony-forming efficiency assays show that MEG3 inhibits colony formation in CH157-MN cells by approximately 80%. Furthermore, MEG3 stimulates p53-mediated transactivation in these cell lines. Therefore, these data are consistent with the hypothesis that MEG3, which encodes a noncoding RNA, may be a tumor suppressor gene at chromosome 14q32 involved in meningioma progression via a novel mechanism.

Increased phosphorylation of vimentin in noninfiltrative meningiomas

BACKGROUND

Tissue invasion or tissue infiltration are clinical behaviors of a poor-prognosis subset of meningiomas. We carried out proteomic analyses of tissue extracts to discover new markers to accurately distinguish between infiltrative and noninfiltrative meningiomas.

METHODOLOGY/PRINCIPAL FINDINGS

Protein lysates of 64 different tissue samples (including two brain-invasive and 32 infiltrative tumors) were submitted to SELDI-TOF mass spectrometric analysis. Mass profiles were used to build up both unsupervised and supervised hierarchical clustering. One marker was found at high levels in noninvasive and noninfiltrative tumors and appeared to be a discriminative marker for clustering infiltrative and/or invasive meningiomas versus noninvasive meningiomas in two distinct subsets. Sensitivity and specificity were 86.7% and 100%, respectively. This marker was purified and identified as a multiphosphorylated form of vimentin, a cytoskeletal protein expressed in meningiomas.

CONCLUSIONS/SIGNIFICANCE

Specific forms of vimentin can be surrogate molecular indicators of the invasive/infiltrative phenotype in tumors.

The relationship between histomorphological characteristics and Ki-67 proliferation index in meningiomas

OBJECTIVES

This study had two aims. The first was to use the Ki 67 proliferation index (Ki-67 PI) to study the relationship between the proliferation potential and histopathological features such as mitosis, necrosis, loss of architecture, small cell change, hypercellularity, pleomorphism, brain invasion, dura invasion, bone invasion, and histological grade. The second aim was to compare primary and recurrent meningioma with respect to morphological characteristics and Ki-67 PI values.

BACKGROUND

Meningiomas are tumors whose histological features do not predict their biological behavior. Despite their slow growth and even after total resection, recurrence may occur

METHODS

A total of 245 meningioma cases in whom Ki-67 PI was studied were included in the study. The cases were assessed with respect to 10 morphological characteristics, and a possible significant relationship between these and Ki 67 PI was statistically tested.

RESULTS

We found a statistically significant relationship between Ki-67 PI and mitotic activity, necrosis, loss of architecture, small cell change, brain invasion. In contrast to brain invasion, no significant relationship was present between dura or bone invasion and Ki-67 PI. We identified asignificant increase in the histological grade, mitotic activity and Ki-67 PI value of recurrent tumors, as compared to primary ones

CONCLUSION

Ki-67 PI values overlap in different grades. This overlapping might be due to the heterogeneity of biological activity within the tumor tissue (Tab. 2, Fig. 7, Ref. 21).

Atypical histopathologic type of cystic meningioma

The authors report a 21-year-old male with an atypical cystic meningioma in the right parietal area. On T1-weighted imaging (T1WI), the solid component was hypointense, while on T2-weighted imaging (T2WI), it was hyperintense. On T1WI, the cystic component was hypointense, and on T2WI, it was hyperintense. The authors review the literature about incidence, locations, MRI features, cyst type, and intraoperative managements of atypical cystic meningiomas.

The cell growth inhibitory transcription factor C/EBPdelta is expressed in human meningiomas in association with low histological grade and proliferation index

CCAAT/enhancer binding protein (C/EBP) delta is a transcription factor which has been demonstrated to mediate the growth arrest of mammary and prostate cancer cell lines. It is induced by several stimuli including inflammatory cytokines. In this study, C/EBPdelta immunohistochemical expression was assessed in 49 meningiomas of different histotype and grade and correlated with a variety of clinico-pathological data and with the overall and recurrence-free survival of the patients. Positive staining was observed in the nuclei of neoplastic cells in 22 out of the 49 cases analyzed. C/EBPdelta expression was significantly associated with a low histological grade and proliferation index, reflected by low Ki-67 labeling index (LI) and mitotic activity, and with the presence of intra-tumoral inflammatory infiltrate and the absence of necrosis. In addition, the absence of C/EBPdelta was significantly correlated with a shorter disease-free interval. Our findings suggest that C/EBPdelta expression may prevent the development of recurrences by inhibition of neoplastic growth in meningiomas. If further studies confirm its induction by inflammatory mediators, this might be exploited in novel therapies to prevent recurrences in meningiomas.

Clear-cell meningioma of the anterior cranial fossa. Case report and review of the literature

Clear-cell meningioma (CCM) is a rare subtype of meningioma which occurs at a younger age and has a higher recurrence rate than other subtypes (WHO grade II). CCM usually occur in younger patients and is located in the posterior fossa and spine. The authors report the first case of olfactory groove mixed clear-cell meningioma. A 66-year-old woman was admitted to the SS. Annunziata Hospital (Taranto, Italy) in January 2007 with a two-year history of subtle changes in personality and mental function. On neurologic examination she presented a loss of sense of smell. The magnetic resonance imaging (MRI) showed an olfactory groove meningioma. The computed tomography (CT) and MRI features of CCM are not different from those of common meningiomas. The tumor was totally removed by frontolateral approach on January 24, 2007). Histological examination showed that the tumor was composed of sheet-like uniform and polygonal cells, with abundant clear cytoplasm, and small and bland nuclei. The cytoplasm was heavily laden with granular periodic acid Schiff-positive and diastase-sensitive material representing glycogen. There were no rich vascular networks but scattered collagen bundles within the tumour, little foci areas of necrosis and whorls of meningothelial cells. The neoplastic cells were positive for epithelial membrane antigen (EMA) and vimentin, and negative for glial fibrillary acidic protein (GFAP)? S-100?chromogranin A; Ki-67 labelling showed an index of 1%. The final diagnosis was mixed clear-cell meningioma. Until now only 38 intracranial CCM cases had been reported in English language literature. Different diagnoses for CCM include lesions with clear cell appearance such metastases of renal cell carcinoma and sarcoma, hemangioblastoma, ependymoma, oligodendroglioma, germinoma, chordoma, pleomorphic xanthoastrocytoma, lipid-rich glioblastoma, microcystic and lipomatous meningioma.

An Ultrastructural and Immunohistochemical Study of Microcystic Meningioma with Emphasis on Matrix Proteins and Connexin 26 Type Gap Junctions

Although the histopathological subtypes of meningioma do not themselves appear to have prognostic significance, they are collectively important for defining the overall histopathological entity of microcystic meningioma (MCM) and allowing a distinction from other intracranial tumors, such as capillary hemangioblastoma, glioma, and metastatic renal cell carcinoma showing similar histology. Four cases of MCM were analyzed by conventional histology, immunohistochemistry, and electron microscopy. The present series of MCM was characterized by spindle- or cobweb-shaped tumor cells, characteristically associated small blood vessels, and a peculiar microcystic pattern. Among the microcystic meningeal tumor tissue, small areas of conventional subtypes were identified. Immunohistochemically, tumor cells showed the mesenchymal features of vimentin positivity and a rich distribution of matrix proteins around tumor cells. They lacked epithelial marker positivity but were faintly EMA positive. Ultrastructurally, primitive cellular junctions, desmosomes, and gap junctions were frequently seen between tumor cells. The gap junctions correlated with connexin 26 immunoreactivity. Although lacking an obvious epithelial nature, these features could be interpreted as showing an abortive differentiation mimicking meningothelial (arachnoidal) cells, which, physiologically, regulate cerebrospinal fluid between blood vessels and brain parenchyma.

Disseminated intravascular coagulation complicating resection of a malignant meningioma

A 70-year-old woman developed disseminated intravascular coagulation (DIC) during a craniotomy for a parasagittal anaplastic/malignant meningioma. This was successfully treated with rapid resection of the tumour and haematological replacement, but a poor neurological outcome resulted. The tumour was demonstrated to express tissue factor, an important causative factor in other tumour associated DIC and previously shown to be expressed by malignant meningiomas. A link between the two is suggested.

Primary extracranial meningiomas: an analysis of 146 cases

Primary extracranial meningiomas are rare neoplasms, frequently misdiagnosed, resulting in inappropriate clinical management. To date, a large clinicopathologic study has not been reported. One hundred and forty-six cases diagnosed between 1970 and 1999 were retrieved from the files of the Armed Forces Institute of Pathology. Histologic features were reviewed, immunohistochemistry analysis was performed (n = 85), and patient follow-up was obtained (n = 110). The patients included 74 (50.7%) females and 72 (49.3%) males. Tumors of the skin were much more common in males than females (1.7:1). There was an overall mean age at presentation of 42.4 years, with a range of 0.3-88 years. The overall mean age at presentation was significantly younger for skin primaries (36.2 years) than for ear (50.1 years) and nasal cavity (47.1 years) primaries. Symptoms were in general non-specific and reflected the anatomic site of involvement, affecting the following areas in order of frequency: scalp skin (40.4%), ear and temporal bone (26%), and sinonasal tract (24%). The tumors ranged in size from 0.5 up to 8 cm, with a mean size of 2.3 cm. Histologically, the majority of tumors were meningothelial (77.4%), followed by atypical (7.5%), psammomatous (4.1%) and anaplastic (2.7%). Psammoma bodies were present in 45 tumors (30.8%), and bone invasion in 31 (21.2%) of tumors. The vast majority were WHO Grade I tumors (87.7%), followed by Grade II (9.6%) and Grade III (2.7%) tumors. Immunohistochemically, the tumor cells labeled for EMA (76%; 61/80), S-100 protein (19%; 15/78), CK 7 (22%; 12/55), and while there was ki-67 labeling in 27% (21/78), <3% of cells were positive. The differential diagnosis included a number of mesenchymal and epithelial tumors (paraganglioma, schwannoma, carcinoma, melanoma, neuroendocrine adenoma of the middle ear), depending on the anatomic site of involvement. Treatment and follow-up was available in 110 patients: Biopsy, local excision, or wide excision was employed. Follow-up time ranged from 1 month to 32 years, with an average of 14.5 years. Recurrences were noted in 26 (23.6%) patients, who were further managed by additional surgery. At last follow-up, recurrent disease was persistent in 15 patients (mean, 7.7 years): 13 patients were dead (died with disease) and two were alive; the remaining patients were disease free (alive 60, mean 19.0 years, dead 35, mean 9.6 years). There is no statistically significant difference in 5-year survival rates by site: ear and temporal bone: 83.3%; nasal cavity: 81.8%; scalp skin: 78.5%; other sites: 65.5% (P = 0.155). Meningiomas can present in a wide variety of sites, especially within the head and neck region. They behave as slow-growing neoplasms with a good prognosis, with longest survival associated with younger age, and complete resection. Awareness of this diagnosis in an unexpected location will help to avoid potential difficulties associated with the diagnosis and management of these tumors.

[Immunohistochemical expression of progesterone receptor in relationship with histological grade and risk of relapses in intracranial meningiomas]

INTRODUCTION

Meningiomas are frequent primary neoplasms of the central nervous system, usually benign and susceptible to healing through surgery. The histological grade of the WHO and the extension of the initial surgical resection are determining prognostic factors in these tumors. Nevertheless, a recurrence rate close to 20 % in benign meningiomas completely diseccated arises the need of considering new prognostic factors.

METHODS

A total of 93 cases were selected for the immunohistochemical study of the progesterone receptor (PR) in relation to the histological grade and the risk of recurrencies in meningiomas.

RESULTS

Though the immunohistochemical labelling index (LI) of the PR decreased with the progression of the histological grade (means of 27.37 % for grade I, 17.89% for grade II, and 13.50% for grade III), such correlation was not statistically significant and the cut off estimated in 20% was not satisfactory to discriminate among benign meningiomas (grade I) and non benign (grades II-III) due to its poor sensitivity (56.10%) and positive predictive value (56.10 %). The comparison of the LI of the PR among non recurrent meningiomas (36.35 %) and recurrent (22.10%) was neither statistically significant, but permitted to establish a useful cut off of 40% (LI >40% in 13/23 non recurrent tumors and <40% in 19/23 recurrent tumors) with a sensitivity of 82.61% and a positive predictive value of 65.52%.

CONCLUSION

The LI of the PR is apparently not related to the histological grade of the meningiomas, but is significantly smaller in recurrent meningiomas. A meningioma with a LI of the PR less than 40 % suggests the risk of recurrences.

Expression of iron-related genes in human brain and brain tumors

BACKGROUND

Defective iron homeostasis may be involved in the development of some diseases within the central nervous system. Although the expression of genes involved in normal iron balance has been intensively studied in other tissues, little is known about their expression in the brain. We investigated the mRNA levels of hepcidin (HAMP), HFE, neogenin (NEO1), transferrin receptor 1 (TFRC), transferrin receptor 2 (TFR2), and hemojuvelin (HFE2) in normal human brain, brain tumors, and astrocytoma cell lines. The specimens included 5 normal brain tissue samples, 4 meningiomas, one medulloblastoma, 3 oligodendrocytic gliomas, 2 oligoastrocytic gliomas, 8 astrocytic gliomas, and 3 astrocytoma cell lines.

RESULTS

Except for hemojuvelin, all genes studied had detectable levels of mRNA. In most tumor types, the pattern of gene expression was diverse. Notable findings include high expression of transferrin receptor 1 in the hippocampus and medulla oblongata compared to other brain regions, low expression of HFE in normal brain with elevated HFE expression in meningiomas, and absence of hepcidin mRNA in astrocytoma cell lines despite expression in normal brain and tumor specimens.

CONCLUSION

These results indicate that several iron-related genes are expressed in normal brain, and that their expression may be dysregulated in brain tumors.

Synthesis and in vitro characterization of radioiodinatable benzodiazepines selective for type 1 and type 2 cholecystokinin receptors

Radiolabeled antagonists of specific peptide receptors identify a higher number of receptor binding sites than agonists and may thus be preferable for in vivo tumor targeting. In this study, two novel radioiodinated 1,4-benzodiazepines, (S)-1-(3-iodophenyl)-3-(1-methyl-2-oxo-5-phenyl-2,3-dihydro-1H-benzo[e][1,4]diazepin-3-yl)urea (9) and (R)-1-(3-iodophenyl)-3-(1-methyl-2-oxo-5-phenyl-2,3-dihydro-1H-benzo[e][1,4]diazepin-3-yl)urea (7), were developed. They were characterized in vitro as high affinity selective antagonists at cholecystokinin types 1 and 2 (CCK(1) and CCK(2)) receptors using receptor binding, calcium mobilization, and internalization studies. Their binding to human tumor tissues was assessed with in vitro receptor autoradiography and compared with an established peptidic CCK agonist radioligand. The (125)I-labeled CCK(1) receptor-selective compound 9 often revealed a substantially higher amount of CCK(1) receptor binding sites in tumors than the agonist (125)I-CCK. Conversely, the radioiodinated CCK(2) receptor-selective compound 7 showed generally weaker tumor binding than (125)I-CCK. In conclusion, compound 9 is an excellent radioiodinated nonpeptidic antagonist ligand for direct and selective labeling of CCK(1) receptors in vitro. Moreover, it represents a suitable candidate to test antagonist binding to CCK(1) receptor-expressing tumors in vivo.

Allelic loss on chromosomes 1p32, 9p21, 13q14, 16q22, 17p, and 22q12 in meningiomas associated with meningioangiomatosis and pure meningioangiomatosis

Meningioangiomatosis (MA) is a rare lesion appearing sporadically or as a part of neurofibromatosis 2. The occurrences of meningiomas arising from MA (MA-M) have raised doubts about the traditional concept of a hamartomatous origin for MA. Cytogenetic or molecular studies on MA, with or without meningiomas, are limited because of the rarity of MA. The current study was to evaluate the loss of heterozygosity (LOH) in seven cases of MA-M and two cases of pure MA. LOH on six chromosomes (1p32, 9p21, 13q14, 16q22, 17p, and 22q12) were investigated using 13 sets of microsatellite markers, including D1S193, D1S463, D22S193, D22S929, D22S282, TP53, D17S796, D16S421, D16S512, D13S118, D13S153, D9S162, and D9S104. PCR was performed using each marker and polymorphic analysis was accomplished by silver staining. Immunohistochemical stain for Ki-67 was carried out and labeling index was measured by using a semiquantitative manual counting method. The meningioma portions of MA-Ms showed LOH for loci on chromosomes 22q12, 9p21, and 1p32 in 57.1% (4/7), 28.6% (2/7), and 28.6% (2/7) of cases, respectively. The MA portions of MA-M had a LOH for loci on 22q12 in 28.6% (2/7) of cases, whereas each pure MA harbored one LOH on either chromosome 22q12 or 9p21. The proliferation indices of MA-Ms were significantly higher in the meningioma than in the MA components. Our data suggest that both the meningioma and the MA undergo the same overlapping clonal process, with the MA-M while undergoing additional genetic alterations that confer a greater proliferative potential.

Anaplastic meningioma in an adolescent: a report of a rare case and brief review of literature

OBJECTIVE

Anaplastic meningioma is an uncommon neoplasm in childhood and adolescence. Due to the rarity, treatment options for anaplastic meningioma in this age group are not clearly outlined.

CASE

A 15-year-old boy presented with a left forehead swelling with a history of a left frontal tumor. Radiological investigations revealed a dura-based tumor with a large extracranial and a smaller intracranial component. Craniotomy with near-total excision of the tumor was performed. Histopathological examination of the tumor showed features of an anaplastic meningioma. The patient is currently receiving radiotherapy and chemotherapy. However, he has developed scalp swellings while on radiotherapy.

CONCLUSION

Anaplastic meningioma is extremely rare in children. Extensive sampling is required to recognize the meningothelial nature of the tumor and immunohistochemistry helps in making an accurate diagnosis in such cases. Therapeutic interventions in such cases need to be closely monitored due to the aggressive behavior of this tumor.

RNAi-mediated downregulation of radiation-induced MMP-9 leads to apoptosis via activation of ERK and Akt in IOMM-Lee cells

Patients afflicted with meningiomas are most often treated with radiation therapy followed by surgical resection. However, resistance to radiation treatment has been well documented among different cancers of the brain. In this study, we demonstrate that the malignant meningioma cells (IOMM-Lee cells) overexpress MMP-9 at both the mRNA and protein levels after radiation treatment. We confirmed an increase in the invasive potential of irradiated cells through spheroid migration and matrigel invasion assays. Knockdown of MMP-9 using an adenoviral siRNA construct blocked MMP-9 expression, reduced the invasive nature of cells, and subsequently led to apoptosis. Western blot analysis revealed the activation of ERK, Akt and Fas as well as a decrease in c-JUN levels. Cleavage of PARP and TUNEL-positive characteristics confirmed apoptotic cell death in Ad-MMP-9 infected cells. Treatment with U0126 and transfection with dominant negative ERK plasmid resulted in the decreased phosphorylation of ERK and Akt. Ectopic expression of HA myr-Akt was found to be associated with an increase in pERK, and treatment with LY294002 was shown to block the phosphorylation of Akt and ERK with the restoration of c-JUN. In conclusion, our data suggest that radiation increases MMP-9 expression and the invasive nature of IOMM-Lee cells, both of which can be reversed with siRNA-mediated downregulation of MMP-9, which leads to ERK and Akt-mediated apoptosis.

Sstr2A immunohistochemical expression in human meningiomas: is there a correlation with the histological grade, proliferation or microvessel density?

Somatostatin anti-proliferative and anti-angiogenic activities, together with the expression of somatostatin receptors (sstrs), account for the use of somatostatin analogues in the treatment of human tumours. In the present study, sstr2A immunohistochemical expression was analyzed in grade II and III meningiomas and was compared with that revealed in grade I meningiomas. Thirty-five formalin-fixed paraffin-embedded meningiomas, comprising 13 grade I, 19 grade II and 3 grade III tumours, according to the WHO 2007 classification, were submitted to immunohistochemical assays for sstr2A. Moreover, in the same cohort of tumours, the immunoexpression of CD105, a specific marker for neo-angiogenesis, as well as the Ki-67 labelling index (LI), reflecting the proliferative activity of the meningiomas, were recorded. Sstr2A immunoreaction was evidenced in 26/35 cases and was localized at the cytoplasm and the plasma membrane in 12 and in 14 cases, respectively. Specifically, a positive staining was found in 7/13 grade I, in 16/19 grade II and in 3/3 grade III tumours, thus demonstrating that sstr2A is frequently expressed in high grade meningiomas. A significantly higher microvessel density (MVD), assessed by CD105 immunostaining and Ki-67 LI were evidenced in high grade meningiomas. A significant correlation was recorded between sstr2A expression and a high MVD of the meningiomas. The existence of a correlation between sstr2A expression and the entity of neo-angiogenesis provides the basis for the use of somatostatin analogue-based therapies in the treatment of meningiomas.

[Preparation and distribution of polyclonal antibodies against human PIWIL3 protein in tumor tissues]

AIM

To prepare specific antibodies against human PIWIL3 protein of Argonaute family and study its expression and distribution in human tumors.

METHODS

To synthesize the polypeptide using the optimal polypeptide immunogens based on sequence homology and peptide immunogenicty in the internal polypeptide selecting database. The synthesized polypeptide were combined with KLH, then immunized the experimental rabbits to produce antiserum. The antiserum was purified by gels custodited the polypeptide using affinity chromatograph, and validated its ability to combine with the corresponding proteins by enzyme-linked immunosorbentassay (ELISA) and Western blot. The expression and distribution of PIWIL3 protein were detected by human tumor tissue biochips.

RESULTS

The specific antibodies against human PIWIL3 proteins were prepared and had high purity. PIWIL3 proteins were expressed in the cytoplasma of human astrocytic glioma and meningioma.

CONCLUSION

The specific antibodies against human PIWIL3 protein have been successfully prepared by using the internal polypeptide selecting database to obtain the optimal polypeptide immunogens, which are distinguished from other sequence homology proteins in the subfamily. These antibodies will have potential value for human PIWIL3 protein in human specific tumor pathogenesis.

[Expression of SV40Tag, Rb and IRS-1 in glioma detected by tissue microarray and their relation with tumorigenesis and progression of gliomas]

OBJECTIVE

To determine the expression of SV40Tag, Rb and IRS-1 in gliomas and to identify their function in gliomagenesis and progression.

METHODS

Tissue microarrays were constructed containing 118 samples including human glioma and meningioma, experimental glioma, and normal human brain tissue. The expression of SV40Tag, Rb, IRS-1, SV40Tag combined with Rb, and SV40Tag combined with IRS-1 were assayed by immunofluorescence or immunohistochemical techniques. The expression ratio and level were analyzed.

RESULTS

The expressions of SV40Tag, Rb and IRS-1 were detected in gliomas and benign brain tumors. Their positive expression rate in glioma was 65.9%, 64.6% and 48.8%, respectively, with a statistically non-significant difference between the malignant and benign brain tumors. The malignant degree was positively correlated with SV40Tag and IRS-1, but negatively correlated with Rb expression. The combined expression rate of SV40Tag and Rb was 51.2%, and the combined expression rate of SV40Tag and IRS-1 was 40.2%. In the normal human brain tissue only the expression of Rb (77.8%, 7/9) and IRS-1 (22.2%, 2/9) were detected, but expression of SV40Tag could not be observed.

CONCLUSION

Our findings that no expression of SV40Tag was observed in normal human brain tissue indicates that expression of SV40Tag may play an important role in the pathogenesis of glioma. It may be assumed that after SV40 virus invading human body, Rb disfunction and IRS-1 activation promote the malignant transformation of cells, which could be one of important factors in pathogenesis and procession of glioms.

Immunohistochemical study of the extracellular matrix proteins laminin, fibronectin and type IV collagen in secretory meningiomas

The extracellular matrix plays a pivotal role in numerous cellular functions during normal and pathological processes. Secretory meningiomas are rare histological meningioma subtypes that have benign behavior, are highly vascularized and are frequently accompanied by massive peritumoral edema. The aim of this study was to assess in secretory meningiomas the immunohistochemical expression of laminin, fibronectin and type IV collagen, proteins found in the extracellular matrix. Extracellular matrix proteins were evaluated in samples from six secretory meningiomas using a semiquantitative scale ranging from not detected (0) to marked (3). Laminin expression was not detected in two cases, but was minimal in one, moderate in one and marked in the remaining cases. Fibronectin expression was absent in two cases, minimal in two, moderate in one and marked with generalized distribution in the remaining case. Type IV collagen expression was minimal in three cases, moderate in two and marked with generalized distribution in the remaining case. Our results are indicative of significant neoangiogenic activity. Meningiomas increase in size through increased production of extracellular matrix; furthermore, the proliferation of cells typically associated with neoplasia requires considerable interaction with the extracellular matrix.

Sex steroid and epidermal growth factor profile of giant meningiomas associated with pregnancy

BACKGROUND

An association between meningioma, breast cancer, and increased growth of meningiomas during pregnancy, and the luteal phase of the menstrual cycle have been shown in previous reports, but the mechanisms still remain unclear. These data suggest that sex steroids and growth factors may have a role in the growth of meningiomas. This is an important factor to consider during the development of more effective nonsurgical treatment options.

METHODS

We described 3 patients with meningioma who presented during the early postpartum period. The lesions were completely resected, and immunohistochemical evaluation of PR, ER, EGF receptor, and Ki67 antigen was performed.

RESULTS

Pathologic studies of tumor specimens revealed atypical meningioma (grade 2), syncytial meningioma (grade 1), and transitional-psammomatous meningioma (grade 1), for cases 1, 2, and 3, respectively. Immunohistochemical studies demonstrated positive PR staining in all of the cases, and there was no immunostaining for ER in any of the cases. Immunohistochemistry for EGF receptor showed membranous staining in less than 10% of the tumor cells, membranous staining in more than 50% of the tumor cells, and no staining in cases 1, 2, and 3, respectively. Immunohistochemistry for Ki67 resulted in positive staining in 20% of the tumor cells for case 1, 10% for case 2, and less than 5% for case 3.

CONCLUSIONS

Although many reports indicating an association between meningioma and pregnancy have been published, the number of immunohistochemical studies is limited. This study suggested the importance of targeting the PR, Ki67 antigen, and EGF receptor in the development of nonsurgical therapeutic regimens.

Giant intracranial endolymphatic sac tumor (ELST). Case presentation and histogenetic considerations

We present a giant tumor of the skull base compressing the brain in a 40-years-old man. The tumor was policystic at imaging. Its histopathology, immunohistochemical profile and long evolution suggest an endolymphatic sac tumor (ELST), a rare case of neoplasia. Since the patient had multiple otolaryngological procedures in his medical history, a possible traumatic pathogenesis could be suspected. On the other way, some immunohistochemical aspects found in our case may imply a histogenesis divergent from that currently accepted. This could be from either the organ of Corti or some local cells that generate a resemblance with a systemic tumor, the so-called benign mesothelioma. Further studies are needed in order to clarify this topic.

Expression of vascular endothelial growth factor in human meningiomas and peritumoral brain areas

Vascular endothelial growth factor (VEGF) is a regulator of angiogenesis, vasculogenesis, and vascular permeability. Recent reports suggest that VEGF may play a critical role in formation of peritumoral brain edema (PTBE) associated with meningiomas. While VEGF expression has been shown in meningiomas, studies have not focused on VEGF in the adjacent peritumoral brain regions. The present study examined the protein and gene expression of VEGF in human meningiomas and peritumoral brain areas. Biopsies were obtained from 37 patients. Immunohistochemical staining and immunoblotting were performed to detect the expression of VEGF protein. Reverse-transcriptase polymerase chain reaction (RT-PCR) was used to analyze the presence and quantity of VEGF mRNA. The extent of PTBE was estimated as an edema index (EI) based on preoperative magnetic resonance imaging. In meningiomas, western blot and RT-PCR results were congruent and the expression of both protein and mRNA had a significant correlation with EI. However, in peritumoral areas, western blot results were not consistent with the RT-PCR results. Protein results showed high correlation with EI, but mRNA was almost undetectable. In VEGF-positive cases, a decreasing gradient of VEGF protein expression was observed with increasing distance from tumors. These data suggest that peritumoral tissue does not produce VEGF and that VEGF protein levels in peritumoral tissues have a high correlation with EI. We conclude that VEGF macromolecules are secreted by the tumor tissue and enter peritumoral normal brain tissue to induce edema.

Primary intra-diploic meningioma in a child

BACKGROUND

Primary intra-diploic meningiomas are uncommon in childhood and, at the clinical onset, may be confused with other and more frequent bone tumours because they lack specific clinical and radiological characteristics. Surgery is indicated not only to remove the lesion but also to obtain an accurate histological diagnosis.

CASE REPORT

We report the case of a young girl who presented with a recently developed subcutaneous hard mass in the left pterional region. Neuroradiological investigations revealed an intra-osseous lytic mass with a sclerotic reaction. Diagnosis was possible only after the total removal of the tumour and its histological examination.

Specific genes expressed in association with progesterone receptors in meningioma

An association between hormones and meningioma has been postulated. No data exist that examine gene expression in meningioma by hormone receptor status. The data are surgical specimens from 31 meningioma patients undergoing neurosurgical resection at Brigham and Women's Hospital from March 15, 2004 to May 10, 2005. Progesterone and estrogen hormone receptors (PR and ER, respectively) were measured via immunohistochemistry and compared with gene expression profiling results. The sample is 77% female with a mean age of 55.7 years. Eighty percent were grade 1 and the mean MIB was 6.2, whereas 33% and 84% were ER+ and PR+, respectively. Gene expression seemed more strongly associated with PR status than with ER status. Genes on the long arm of chromosome 22 and near the neurofibromatosis type 2 (NF2) gene (22q12) were most frequently noted to have expression variation, with significant up-regulation in PR+ versus PR- lesions, suggesting a higher rate of 22q loss in PR- lesions. Pathway analyses indicated that genes in collagen and extracellular matrix pathways were most likely to be differentially expressed by PR status. These data, although preliminary, are the first to examine gene expression for meningioma cases by hormone receptor status and indicate a stronger association with PR than with ER status. PR status is related to the expression of genes near the NF2 gene, mutations in which have been identified as the initial event in many meningiomas. These findings suggest that PR status may be a clinical marker for genetic subgroups of meningioma and warrant further examination in a larger data set.

Simultaneously occurring vestibular schwannoma and meningioma in the cerebellopontine angle: case report and literature review

Simultaneously occurring multiple primary brain tumors of different histological types are rare, and the coexistence of schwannoma and meningioma in the same cerebellopontine angle (CPA) without neurofibromatosis is extremely rare. A 57-year-old female patient presented with headache, speech disturbance, left facial numbness and deafness in the left ear. Magnetic resonance imaging demonstrated two different tumors in the left CPA. These tumors were not in continuity. The tumors were totally removed through the left suboccipital approach. Histopathological examination revealed that the large tumor was a vestibular schwannoma and the smaller was a meningioma. Neurofibromatosis was not diagnosed in the patient. No recurrence was observed at the end of 9 years after the operation. The simultaneous occurrence of vestibular schwannoma and meningioma in the CPA appears coincidental. This association must be kept in mind if two different tumors are detected radiologically in the same CPA.

[Meningiomas: anatomical pathology and molecular biology]

In the past 5-10 years, there has been a considerable progress the understanding of the biology of meningioma. The most important advances have been made by comprehensive studies of the pathogenesis of meningioma in molecular genetics. Several target genes could be identified for mutation or inactivation. Additional chromosomal regions that are usually subject to deletion or amplification and point to the presence of tumor suppressor genes or proto-oncogenes were found. The revised and updated 2000 WHO Classification is a major innovation in the histopathology of meningiomas. The new classification system more precisely and objectively determines the grade of meningioma, which allows one to more logically make a prognosis of the recurrence and aggressive behavior of the tumor. The present overview places particular emphasis on recent advances in its molecular biology. It summarizes the most important aspects of the classification of meningiomas, which makes it possible to include the results of biological observations into the respective context, and also considers the mechanisms of angiogenesis and edema development and the role of hormonal receptors in meningiomas.

Density of microvessels positive for CD105 (endoglin) is related to prognosis in meningiomas

Microvessel density (MVD) is considered to be a prognostic marker in many tumours. Nevertheless, conflicting results were achieved regarding its prognostic role in meningiomas when it was quantified through pan-endothelial markers such as CD34, CD31 or Factor VIII. In the present study, MVD was assessed in meningiomas through the specific marker for neo-angiogenesis CD105. Fifty-four formalin fixed, paraffin embedded, surgical cases of meningiomas (WHO 28 grade I and 26 grade II) as well as ten normal leptomeningeal samples were submitted to immunohistochemical analysis for CD105. CD34 immuno-expression was also evaluated on consecutive parallel sections. For each case, MVD was estimated in terms of number of vessels/mm(2). CD105 was not evidenced in normal samples, whereas it was demonstrated in the vessels within 14/28 WHO grade I cases and within 24/26 WHO grade II meningiomas. On the contrary, CD34 antibody stained blood vessels in both normal and neoplastic samples; moreover, in each case, it stained more microvessels than CD105 antibody (25.33 +/- 21.16 vs. 50.72 +/- 26.75). Higher CD105 counts were significantly correlated with higher histological grade and Ki-67 LI > 4%. No statistical significant correlations were encountered between MVD measured by either CD105 and CD34 and sex, age, site of tumour or extent of surgical resection. CD105-MVD, but not CD34-MVD, showed an inverse significant correlation with overall survival and recurrence-free survival. In conclusion, our study suggests the higher specificity of CD105 in comparison to pan-endothelial markers in the evaluation of meningioma neo-angiogenesis, and its higher prognostic significance. CD105 might serve as a target for therapeutic approaches blocking blood supply in meningiomas.

Frontotemporal clear cell meningioma. Report of 3 cases

Clear cell meningioma (CCM) is an uncommon meningioma. Some cases have been reported, and the localization of most of them is the spinal region. We present 3 cases of CCMs in the frontotemporal lobes. All cases were postmenopausal women with a history of arterial hypertension and uterine leiomyomatosis. The radiologic appearance in 2 cases was similar to that of dural hematomas, and in 1 case, the imaging study was consistent with the diagnosis of meningioma. On histologic examination, there were sheets of glycogenated polygonal cells with abundant clear cytoplasm and round, uniform, bland appearing nuclei. Numerous hyalinized blood vessels and collagenous stroma with fibrillary appearance were present in 2 cases. They were immunoreactive to epithelial membrane antigen, epithelial cell adhesion molecule, and progesterone receptors. However, 2 cases showed weak and focal reaction to Her-2/neu. In our knowledge, some cases of CCMs have been reported and no immunoexpression has been noted with those markers used. These cases illustrate a rare variant of meningioma in the frontotemporal lobes and their immunohistochemical profiles. Differential diagnosis is discussed.

Association between absence of epidermal growth factor receptor immunoreactivity and poor prognosis in patients with atypical meningioma

OBJECT

The clinical behavior of meningiomas is variable. Because multiple growth factor receptors have been identified in these tumors, the authors sought to assess the capacity of the expression patterns of a subset of these receptors to stratify meningioma cases.

METHODS

Eighty-four meningiomas were analyzed, including 36 benign, 29 atypical, and 19 malignant lesions. Immunohistochemical staining was performed for epidermal growth factor receptor (EGFR), platelet-derived growth factor receptor (PDGFR)-beta, basic fibroblast growth factor receptor (BFGFR), and MIB-1. Survival analyses were performed using follow-up data obtained in patients with newly diagnosed tumors. Immunoreactivity for EGFR was observed in 47% of benign, 48% of atypical, and 42% of malignant tumors. Staining for BFGFR was identified in 89% of benign, 97% of atypical, and 95% of malignant lesions. Immunostaining for PDGFR-beta was evident in all the lesions assessed. Mean MIB-I indices for benign, atypical, and malignant cases were 3.6 (range 0.5-15.3), 8.2 (range 1.5-23.1) and 18.3 (range 1.0-55.8), respectively. Overall mean follow-up duration was 9.0 years (range 5.1-18.8 years). Lack of EGFR immunoreactivity was identified as a strong predictor of shorter overall survival in patients with atypical meningioma (p = 0.003, log-rank test). This association was not evident in cases of benign or malignant meningiomas.

CONCLUSIONS

There is a significant association between EGFR immunoreactivity and prolonged survival in patients with atypical meningioma. Given the variable behavior of atypical meningiomas, EGFR assessment could improve existing strategies for patient stratification and treatment.

Intraventricular rhabdoid meningioma

Rhabdoid meningioma is a rare variant of meningioma, often found in tumour recurrences. We report a 55-year-old woman with a history of intraventricular fibroblastic meningioma, who developed headache and tinnitus 5 years after complete resection of the initial tumour. Imaging confirmed a recurrent tumour in the intraventricular location. Histological analysis revealed rhabdoid meningioma. We reviewed the literature and were unable to find any previously reported cases of intraventricular rhabdoid meningioma.

Follicular lymphoma of the dura associated with meningioma: A case report and review of the literature

A 70-year-old immunocompetent woman who had been radiologically diagnosed with a left parasagittal meningioma 5 years previously developed a palpable subgaleal mass and underwent neurosurgery. Histologically the tumor was composed of thickened fibrotic dural tissue, infiltrated by a follicular lymphoma, of grade IIIB. A coexistent transitional meningioma had been infiltrated by the neoplastic lymphoid tissue. Two months after surgery, the patient developed evidence of extracranial dissemination of the lymphoma to the cervical lymph nodes and was treated with polychemotherapy plus Rituximab and intrathecal methotrextate. The patient is alive and recurrence-free at 1-year follow up. A review of the literature indicates that lymphomas developing primarily in the meninges, have an indolent course and tend to be localized in areas rich in meningothelial cells.

MR spectroscopy in patients with intracranial meningiomas

With magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS), we tried to get more pre-operative information in patients with suspicious meningioma concerning the histologic diagnosis especially regarding WHO Grades I and II meningiomas. Apart from the known spectra and metabolites such as choline, creatine and N-acetyl-aspartate (NAA), recent publications have shown that lactate is often found in necrotic tumor tissue. Within a 2 year period, 39 patients with an intracranial meningioma were studied with MRS. In 62.5% of histologic atypical meningiomas (WHO Grade II), a lactate peak could be demonstrated in the pre-operative MRS. Interestingly, also patients with multiple meningiomas show different spectra of their tumors.

The Quantitative analysis of bFGF and VEGF by ELISA in human meningiomas

The quantitative analysis of VEGF using ELISA in various subtypes of grade I meningiomas reported higher VEGF contents in meningothelial (2.38 ± 0.62 pg/μg protein, n = 7), transitional (1.08 ± 0.21 pg/μg protein, n = 13), and microcystic meningiomas (1.98 ± 0.87 pg/μg protein, n = 5) as compared with fibrous ones (0.36 ± 0.09 pg/μg protein, n = 5). In contrast to VEGF, no difference in the concentrations of bFGF was detected. VEGF levels did not correlate with meningioma grade (1.47 ± 0.23 pg/μg versus 2.29 ± 0.58 pg/μg for 32 and 16 grade I and II, resp), vascularisation (1.53 ± 0.41 pg/μg versus 1.96 ± 0.28 pg/μg for 24 low and 24 high vascularisated tumours, resp), and brain invasion (2.32 ± 0.59 pg/μg versus 1.46 ± 0.27 pg/μg for 7 and 41 patients with and without invasion, resp). The ELISA procedure is, thus, an interesting tool to ensure VEGF and bFGF levels in meningiomas and to test putative correlations with clinical parameters. It is, thus, tempting to speculate that ELISA would also be valuable for the quantitative analysis of other angiogenic growth factors and cytokines in intracranial tumours.

Increase in glutamate as a sensitive indicator of extracellular matrix integrity in peritumoral edema: a 3.0-tesla proton magnetic resonance spectroscopy study

OBJECT

The authors of previous studies based on diffusion tensor imaging have indicated that there are two types of peritumoral edema-namely, edema with preserved structural integrity of the glial matrix and edema with compromised glial matrix. The authors of this study hypothesized that functionality of the glutamate (Glu)-glutamine shuttle, a vital neuron-glia interaction, may be differentially affected by peritumoral edema. They tested this hypothesis using proton magnetic resonance (MR) spectroscopy on a 3.0-tesla system that is capable of quantifying Glu without need of editing.

METHODS

Twenty-three patients, each with a single brain tumor mass and peritumoral edema (nine high-grade gliomas, eight metastatic brain tumors, and six meningiomas), and nine healthy individuals participated in this study. Single-voxel proton MR imaging targeting the region of peritumoral edema was performed using a 3.0-tesla system. Glutamate levels in the peritumoral edema of nonglial tumors was significantly elevated (p < 0.01) compared with edema associated with glial tumors or normal white matter. The finding confirmed that peritumoral edema in nonglial tumors is distinct from that of glial tumors, as previously indicated in diffusion tensor imaging studies. The authors hypothesized that the former condition represents a compensatory increase in activities of the Glu-glutamine shuttle brought about by simple expansion of the extracellular space due to edema.

CONCLUSIONS

The assessment of Glu concentrations in peritumoral edema using 3.0-tesla proton MR spectroscopy may be developed into an objective index of the structural integrity of the glial matrix.