CD68 and CR3/43 immunohistochemical expression in secretory meningiomas

OBJECTIVE

Secretory meningiomas (SMs) are unusual benign meningiomas. SMs are highly vascularized lesions, with angiomatous features and a perivascular arrangement, and they are accompanied frequently by massive peritumoral edema. Microglia have been called the brain's immune system, although the specific role and prognostic significance of microglia remain uncertain. The objective of this study was to analyze the expression of CD68, a macrophage marker specific for resting microglia, and the expression of major histocompatibility complex Class II CR3/43 in SMs.

METHODS

From 1995 to 2002, six patients with SMs were treated surgically at our institution. Immunohistochemistry was used to analyze the expression of CD68 and CR3/43 in tumor specimens. The intensity of expression was graded semiquantitatively. A correlation between immunohistochemical expression and the occurrence of brain edema was studied.

RESULTS

CD68-positive mononuclear cells were observed in neoplastic tissue or around pseudopsammoma bodies and in perivascular areas, with minimal expression in one patient and moderate expression in three patients. CR3/43-positive complexes were detected in mononuclear elongated elements with ameboid extensions, presumably referable to cells at different stages of immunological activation phenomena, with minimal expression in two patients, moderate expression in one patient, and marked expression in one patient. Edema was severe in all patients. Therefore, it may be indirectly hypothesized that edema may not be correlated with the CD68 and CR3/43 immunohistochemical expression.

CONCLUSION

Macrophage infiltration and major histocompatibility complex Class II immunoreactivity in this subtype of meningioma suggest the occurrence of an immune response in the presence of SM.

Expression of Rac3 in human brain tumors

Rac3 may play an important role in tumor growth but little is known about its expression and mutation in human tumor tissues. We examined the expression of Rac3 using RT-PCR and mutation of the Rac3 gene by DNA sequencing. Overexpression of the Rac3 gene occurred in 19% (5/26) of brain tumors; 3 of 9 (33%) meningiomas, 1 of 11 (9%) astrocytomas and 1 of 6 (17%) pituitary adenomas. Two of the 3 meningiomas with Rac3 overexpression were recurrent meningiomas. The only astrocytoma with Rac3 overexpression was a glioblastoma multiforme. Mutation of the Rac3 gene occurred in 63% (12/19) of brain tumours; 4 of 7 (57.1%) meningiomas, 4 of 5 (80%) pituitary adenomas and 4 of 7 (57.1%) astrocytomas. Except in one astrocytoma, the other four tumors with Rac3 overexpression (3 meningiomas and one pituitary adenoma) did not have Rac3 mutations. Our data is the first report of the frequency of Rac3 overexpression and mutation in human brain tumors. Overexpression may be associated with aggressive tumor behavior. The relationship between Rac3 expression and mutation requires further investigation.

Protein 4.1B/differentially expressed in adenocarcinoma of the lung-1 functions as a growth suppressor in meningioma cells by activating Rac1-dependent c-Jun-NH(2)-kinase signaling

Meningiomas are the second most common brain tumor in adults, yet comparatively little is presently known about the dysregulated growth control pathways involved in their formation and progression. One of the most frequently observed genetic changes in benign meningioma involves loss of protein 4.1B expression. Previous studies from our laboratory have shown that protein 4.1B growth suppression in meningioma is associated with the activation of the c-Jun-NH(2)-kinase (JNK) pathway and requires localization of a small unique region (U2 domain) of protein 4.1B to the plasma membrane. To define the relationship between protein 4.1B expression and JNK activation, as well as to determine the mechanism of JNK activation by protein 4.1B, we used a combination of genetic and pharmacologic approaches. In this report, we show that protein 4.1B/differentially expressed in adenocarcinoma of the lung-1 (DAL-1) expression in meningioma cells in vitro results in JNK activation, which requires the sequential activation of Src, Rac1, and JNK. In addition, inhibition of Rac1 or JNK activation abrogates protein 4.1B/DAL-1 growth suppression and cyclin A regulation. Last, protein 4.1B/DAL-1 regulation of this critical growth control pathway in meningioma cells requires the presence of the U2 domain. Collectively, these observations provide the first mechanistic insights into the function of protein 4.1B as a growth regulator in meningioma cells.

Female predominance in meningiomas can not be explained by differences in progesterone, estrogen, or androgen receptor expression

The female predominance in meningioma incidence and association between meningioma and breast cancer suggest that growth of meningiomas is hormone-dependent. There are several discrepancies in literature about the proliferative effect of sex hormones on meningiomas. This study aims to evaluate the hormone receptor status of meningiomas and assess its relation to age, sex, histological grade, recurrence, and proliferation activity. The material was based on consecutive patients operated for meningioma at Tampere University Hospital in 1989-1999. The occurrence of progesterone, estrogen and androgen receptor in patients with primary and recurrent meningiomas was studied immunohistochemically by using specific monoclonal antibodies. Hormonal status was determined in 510 tumor samples. 443 samples were from primary meningiomas and 67 from recurrent tumors. Of the samples, 455 were benign (WHO grade I), 49 atypical (grade II), and 6 malignant (grade III). Of the primary tumor samples, 88% were progesterone receptor positive, 40% were positive for estrogen and 39% for androgen receptors. Grade I meningiomas had significantly higher incidence for estrogen and androgen receptors than higher grade meningiomas. Estrogen positive tumor samples had significantly higher proliferation index than estrogen negative samples. No difference in expression of sex hormone receptors was observed by sexes or age group. Estrogen and androgen receptors may have more influence on the pathogenesis of meningiomas than earlier thought. The higher incidence of meningiomas in women can not be explained by differences of sex hormone receptor expression.

Intraoperative and postoperative gamma detection of somatostatin receptors in bone-invasive en plaque meningiomas

OBJECTIVE

Scintigraphy with a radiolabeled somatostatin analog ((111)In-diethylenetriaminepenta-acetic acid octreotide) detects the somatostatin receptors that are found in vitro in all meningiomas. Previous studies have proved the benefit of radioimmunoguided surgery, with a hand-held gamma probe, for the assessment and removal of neuroendocrine tumors. We conducted a study to determine whether intraoperative radiodetection of somatostatin receptors is feasible and could increase the probability of complete meningioma resection, especially for bone-invasive en plaque meningiomas, which are difficult to control surgically.

METHODS

Eighteen patients with en plaque sphenoid wing and cranial convexity meningiomas were studied by preoperative and postoperative somatostatin receptor scintigraphy. In 10 of them, intraoperative radiodetection with a hand-held gamma probe was performed 24 hours after the intravenous administration of (111)In-diethylenetriaminepenta-acetic acid octreotide. This procedure was combined with a computer-aided navigation system.

RESULTS

All preoperative scintigrams were positive. Intraoperative gamma probe detection was achieved for the invaded bone, dura, and periorbit of sphenoid wing meningiomas. The average tumor/nontumor count ratio was 2:1, with a maximum of 12:1, thus allowing precise detection capable of defining the tumor margins. In three cases of sphenoid wing meningiomas, postoperative scintigrams were helpful for the determination of recurrences that magnetic resonance imaging failed to detect.

CONCLUSION

These preliminary data show that intraoperative radiodetection of somatostatin receptors with a hand-held gamma probe is feasible and may be helpful to guide the surgical removal of bone-invasive en plaque meningiomas. Preoperative and postoperative scintigraphy may be useful for the management and follow-up of patients with these tumors.

Expression of extracellular matrix-degrading proteins in classic, atypical, and anaplastic meningiomas

Although the majority of meningiomas, commonly benign tumors (WHO I), are amenable to surgical resection, a percentage of up to 3% will recur as higher-grade meningiomas with potential brain invasion. Our study aims at the in situ identification of proteolytic, extracellular matrix-degrading enzymes in a broad spectrum of meningiomas. We examined 80 meningiomas (50 classic meningiomas WHO I, 19 meningiomas WHO II, including atypical, chordoid, and clear cell types, as well as 11 anaplastic meningiomas WHO III) for the immunohistochemical expression patterns of cathepsin D and metalloproteinases MMP-2 and MMP-9. Meningiomas of all types and grades revealed a distinct expression of MMP-9 and cathepsin D, while MMP-2 was found predominantly in WHO II and III meningiomas. There was a significant increase in positive tumor cells from WHO grade I to II and III for MMP-2 (p<0.001), but not for cathepsin D (p=0.099). MMP-9 displayed an increased number of positive tumor cells from WHO grade I to II, but a decrease in WHO III meningiomas (p<0.002). Routine screening for the expression of metalloproteinases and cathepsin D will not reveal any new diagnostically or prognostically relevant information. However, these factors may represent a potential target for pharmacological blocking as an anti-invasive therapy.

Telomerase activity and hTERT protein expression in meningiomas: an analysis in vivo versus in vitro

BACKGROUND

Telomere length maintenance is essential for tumorigenesis. Most human tumours stabilise their chromosome ends by telomerase, a specialised reverse transcriptase that adds telomeric repeats (TTAGGG) to these ends. The main components of this telomerase complex are a reverse transcriptase (hTERT) and an integral RNA component (hTR). Most typical meningiomas, however, do not have active telomerase, although some express the hTERT component. The aim of this study was to evaluate telomerase activity and its reverse transcriptase for 33 (30 typical and three atypical) meningiomas in vivo and in vitro.

MATERIALS AND METHODS

Telomerase activity was examined by the telomeric repeat amplification protocol (TRAP) assay. The protein, telomerase reverse transcriptase, was visualised by immunohistochemistry.

RESULTS

In vivo, telomerase activity was detectable in one out of 30 typical meningiomas and in two out of three atypical meningiomas. hTERT protein expression in vivo was positive in 14 out of 33 (42%) cases. The mean percentage of positive nuclei was 12.9% (SD=21.0). In vitro, 22 out of 33 (66%) meningiomas were positive for hTERT, with a mean percentage of positive nuclei of 31.8% (SD=37.1). Only four expressed telomerase activity in vitro, from which three had expressed telomerase activity in vivo. A significant association was found for telomerase activity (p<0.001) and hTERT expression (p<0.001) in vivo versus in vitro; a significant association was found for hTERT expression and telomerase activity in vivo (p<0.05) and in vitro (p<0.05).

CONCLUSION

The results of our study suggest that hTERT expression is an early event in carcinogenesis in contrast to telomerase activity. Fast-proliferating hTERT-positive tumour cells may overgrow in vitro by clonal selection.

[Research on the expression of cancer associated gene in the intracranial tumors]

OBJECTIVE

To investigate the function significance and application value of cancer associated gene (CAGE) in the pathogenesis of intracranial tumors.

METHODS

Semi-quantitative RT-PCR was performed to detect the expression of CAGE gene in 17 normal tissues, 35 meningioma cases and 63 glioma cases.

RESULTS

The CAGE gene was expressing in none of the normal tissues except testis, but in 4 meningioma (11.3%) and 57 glioma cases(90.5%). The expression of CAGE gene showed significant difference between the meningioma and glioma (P<0.001). The amount of CAGE mRNA was 0.5 +/- 0.11, 0.86 +/- 0.23, 1.85 +/- 0.37 or 2.7 +/- 0.46 times of the internal control one in glioma grade I, II, or IV respectively. The expression of CAGE gene increased with the pathological grade(r=0.82).

CONCLUSION

The CAGE plays important role in the pathogenesis of glioma, and may act as the tumor specific antigen for glioma.

Chordoid meningioma, an uncommon variant of meningioma: a clinicopathologic study of 12 cases

AIMS

The study has been undertaken to document the clinicopathological features of 12 cases of chordoid meningioma, operated at All India Institute of Medical Sciences during 1996 to June 2005.

METHODS

Clinical information was retrieved from the records of our Neurosurgery Department. The cases were stained with H&E, Periodic Acid Schiff (PAS) with and without diastase, mucicarmine, giemsa, toluidine blue, alcian blue, reticulin and Masson trichrome. Immunohistochemistry for pancytokeratin, epithelial membrane antigen, vimentin, glial fibrillary acidic protein, MIB-1, Leucocyte common antigen (LCA), CD-3 and CD-20 was done in all cases.

RESULTS

The age ranged from 12-67 years (mean 34.2 years) and three of them occurred in < 18 years. Male to female ratio was 1:1.4. The duration of symptoms varied from 3.5 months to 5 years (mean 14.1 months). No systemic symptoms were noted. The location of tumor in eight cases was in the supratentorial and rest four in the infratentorial compartments. Interestingly, two cases were in intraventricular location, one in the lateral ventricle and other in the fourth ventricle. Microscopic examination showed lobulation with chordoid elements constituting > 95% of the entire tumor area in 11 of the total 12 cases. In one case, chordoid pattern constituted about 30% of the total tumor area; the rest was predominant meningothelial (60%). Mild to severe lymphoplasmacytic cell infiltrate was present in all cases. The histochemical stains showed the pattern of acidic mucin and interestingly revealed the presence of mast cells both in connective tissue stroma and epithelial cell islands. The inflammatory infiltrate was B-cell predominant. MIB-1 labeling index was low (< 2%) in all cases except two, which showed LI of 6% and 8%. Strong diffuse immunoreactivity for vimentin and focal positivity for epithelial membrane antigen was noted in all cases.

CONCLUSIONS

Chordoid meningiomas are predominantly tumors of young adults with predilection for supratentorial location. Intraventricular location, absence of systemic manifestations despite the presence of abundant B-lymphocytes, presence of mast cells and low MIB-1 LI are some of the interesting findings in the present series, which need documentation. Hence, larger number of cases with adequate follow-up data need to be studied further to establish the clinical significance of this variant.

Prognostic value of HER2 expression in meningiomas: an immunohistochemical and fluorescence in situ hybridization study

The aggressiveness of meningiomas is unpredictable. HER2 represents a well-known prognostic factor in various tumors such as breast carcinomas. This work was designed to study HER2 protein expression and HER2 gene amplification in meningiomas and to evaluate their prognostic value. Frozen sections of 35 meningiomas were immunostained for HER2, estrogen receptor, progesterone receptor, E-cadherin, and MIB-1. Meningiomas immunostained for HER2 were further examined for the HER2 gene amplification by dual-color fluorescence in situ hybridization using probes for centromere 17 and 17q11.2-q12. Complete clinical information was obtained in all cases. The study included 15 atypical meningiomas, 3 anaplastic meningiomas, and 17 classic meningiomas. Five atypical/anaplastic meningiomas and 5 classic meningiomas of the whole 35 (28.5%) meningiomas expressed HER2 protein. This was considered as an overexpression in comparison with negative normal meninges. Fluorescence in situ hybridization demonstrated more HER2 gene copy in 4 of these 10 HER2-positive meningiomas. At equivalent histologic grading, meningiomas with HER2 overexpression exhibited similar immunohistochemical parameters of prognostic value than their HER2-negative counterparts; however, the rate of tumor recurrence was significantly higher in meningiomas with HER2 overexpression than in HER2-negative meningiomas. Conversely, HER2 amplification was not associated with recurrence. Some meningiomas exhibit HER2 protein overexpression in part induced by gene amplification. However, only HER2 overexpression could represent an independent prognostic factor in meningiomas.

Tumor extension in high-grade gliomas assessed with diffusion magnetic resonance imaging: values and lesion-to-brain ratios of apparent diffusion coefficient and fractional anisotropy

PURPOSE

To determine whether the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) can distinguish tumor-infiltrated edema in gliomas from pure edema in meningiomas and metastases.

MATERIAL AND METHODS

Thirty patients were studied: 18 WHO grade III or IV gliomas, 7 meningiomas, and 5 metastatic lesions. ADC and FA were determined from ROIs placed in peritumoral areas with T2-signal changes, adjacent normal appearing white matter (NAWM), and corresponding areas in the contralateral healthy brain. Values and lesion-to-brain ratios from gliomas were compared to those from meningiomas and metastases.

RESULTS

Values and lesion-to-brain ratios of ADC and FA in peritumoral areas with T2-signal changes did not differ between gliomas, meningiomas, and metastases (P = 0.40, P = 0.40, P = 0.61, P = 0.34). Values of ADC and FA and the lesion-to-brain ratio of FA in the adjacent NAWM did not differ between tumor types (P = 0.74, P = 0.25, and P = 0.31). The lesion-to-brain ratio of ADC in the adjacent NAWM was higher in gliomas than in meningiomas and metastases (P = 0.004), but overlapped between tumor types.

CONCLUSION

Values and lesion-to-brain ratios of ADC and FA in areas with T2-signal changes surrounding intracranial tumors and adjacent NAWM were not helpful for distinguishing pure edema from tumor-infiltrated edema when data from gliomas, meningiomas, and metastases were compared.

A genetic strategy to overcome the senescence of primary meningioma cell cultures

Even though meningiomas are the second most common brain tumor in adults, little is known about the molecular basis of their growth and development. The lack of suitable cell culture model systems is an impediment to this understanding. Most studies on meningiomas rely on primary, early passage cell lines that eventually senesce or a few established cell lines that have been derived from aggressive variants of meningiomas. We have isolated three primary meningioma cell lines that are negative for telomerase activity. We can overcome the senescence of a Grade III derived meningioma cell line by expressing the telomerase catalytic subunit (hTERT), whereas Grade I meningioma cell lines require the expression of the human papillomavirus E6 and E7 oncogenes in conjunction with hTERT. Meningioma cell lines, immortalized in this manner, maintain their pre-transfection morphology and form colonies in vitro. We have confirmed the meningothelial origin of these cell lines by assessing expression of vimentin and desmoplakin, characteristic markers for meningiomas. Additionally, we have karyotyped these cell lines using array CGH and shown that they represent a spectrum of the genetic diversity seen in primary meningiomas. Thus, these cell lines represent novel cellular reagents for investigating the molecular oncogenesis of meningiomas.

Automated nuclear segmentation in the determination of the Ki-67 labeling index in meningiomas

OBJECTIVE

Assessing the Ki-67 labeling index (LI) is laborious and time consuming. Therefore, an automated computer-based method was developed, which is able to identify and analyze immunolabeled and hematoxylin-stained nuclei in digital images of routine immunohistochemical slides.

MATERIAL AND METHODS

The method is based on a plugin for the public domain image analysis software ImageJ, which runs on every operating system (free download at http://rsb.info.nih.gov/ij/). Percentage of Ki-67 immunostained nuclei were determined in 5 high power fields (x40) of immunostained slides (DAB detection technique, hematoxylin counterstain) of 20 Grade I, 20 Grade II, and 10 Grade III meningiomas conventionally by two independent investigators and automatically, respectively. The time effort was measured for each counting procedure.

RESULTS

Enumerating conventionally or automatically did not reveal any significant differences in the mean labeling indices. Ki-67 LIs discriminated sufficiently between meningiomas of Grade I (median 1.7% Investigator 1 and 1.5% Investigator 2 vs. 1.5% automatically), Grade II (7.6%, 8% vs. 7.3%), and Grade III meningiomas (22%, 21% vs. 22%). The computer-based results correlated very closely with those obtained by manual counting (correlation coefficient = 0.98). The mean time effort for counting procedure per image was 374 s (130 s-435 s) for the conventional and 11 s (7 s-12 s) for the automated method.

CONCLUSIONS

The described method can reliably assess the Ki-67 LI much faster than conventional enumerating. The computerized method has the advantages of objectivity, accuracy, repeatability, and ease of use. There is no request for special stains nor special image acquiring systems. The plugin can be downloaded at the "Morphometrie" section of http://www.uniklinikum-saarland.de/neuropathologie.

PCNA, Ki-67 and hTERT in residual benign meningiomas

BACKGROUND

Relapse in individual patients after incomplete/residual removal of meningiomas cannot be predicted by histology alone as re-growth occurs even in histologically benign meningiomas.

MATERIALS AND METHODS

Proliferating cell nuclear antigen (PCNA), Ki-67 and human telomerase reverse transcriptase (hTERT) labelling indices were measured in histological sections derived from residual meningiomas in 37 patients to assess their relationship to relapse. The labelling index (LI) expressed the percentage of tumour cell nuclei immunoreactive for PCNA, Ki-67 or hTERT in 1,000 tumour cells counted per section. The histological specimens comprised the following 2 groups: (i) stable for at least 10 years after initial partial resection of residual meningiomas: 20 specimens; (ii) relapsing between 11 and 145 months after initial resection of residual meningiomas: 17 specimens.

RESULTS

The proliferative activity and hTERT expression do not directly correlate with every relapse. The PCNA LI significantly differed in the relapsing group (10.8%) compared to the stable group (5.5%) (p=0.08). The Ki-67 LI also was higher in the relapsing group (2.5%) than in the stable group (2.0%), but not statistically significantly (p=0.9). hTERT LI was significantly higher in the relapsing group (27.8%) than in the stable group (7.2%) (p<0.01).

CONCLUSION

The mean PCNA, Ki-67 and hTERT LI were higher in the relapsing group of residual meningiomas than in the stable group, although no statistical difference was found for PCNA and Ki-67. On the other hand, a statistical difference between the two groups of meningiomas was found for hTERT; however, it is no absolute predictor for relapse at the individual patient level.

Schwannomin inhibits tumorigenesis through direct interaction with the eukaryotic initiation factor subunit c (eIF3c)

The neurofibromatosis 2 (NF2) tumor suppressor protein, schwannomin or merlin, is commonly lost upon NF2 gene mutation in benign human brain tumors. We identified the p110 subunit of the eukaryotic initiation factor 3 (eIF3c) as a schwannomin interacting protein. The eIF3 complex consists of approximately 10 subunits whose functions are only recently becoming known. Interaction between schwannomin and eIF3c suggests a role for schwannomin in eIF3c-mediated regulation of proliferation related to changes in protein translation. We found that schwannomin was most effective for inhibiting cellular proliferation when eIF3c was highly expressed. When we examined these proteins in 14 meningiomas, we observed high eIF3c abundance in those that had lost schwannomin expression but low eIF3c abundance in those retaining schwannomin. Consequently, eIF3c appears to be involved in NF2 pathogenesis and deserves to be investigated as a prognostic marker for NF2 and target for treatment of NF2 patient tumors.

Podoplanin is expressed in subsets of tumors of the central nervous system

Immunohistochemical analyses with the monoclonal antibody D2-40 were performed to ascertain the expression of podoplanin (a.k.a. T1-alpha, gp36, or aggrus) in tumors of the central nervous system (CNS) and to determine the diagnostic utility of the antibody. The analyses were performed on 325 tumors of various histologic types. The chief finding was almost constant immunoreactivity in ependymal tumors (37/40, 92.5%), choroid plexus papillomas (8/8, 100%), and meningiomas (100/100, 100%). The reactivity was considered "tissue-specific," as the corresponding normal tissue of each tumor was also found to express podoplanin. In addition, expression, not committed to the lineages, was found in many other tumor types, including astrocytic tumors, medulloblastomas, and hemangioblastomas, with variable frequency and intensity. The way of expression was not fully understood, but the expression in astrocytic tumors seemed to be associated with pronounced fibrous properties or malignant phenotype, as was shown by high-frequent expression in pilocytic astrocytomas (12/12, 100%) and glioblastomas (29/35, 82.9%). The present study has shown that podoplanin is expressed in several types of CNS tumors with variable frequency and intensity. Given the widespread expression of podoplanin, the antibody D2-40 is of little use in diagnostic practice for CNS tumors.

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.

Protein p62 common in invaginations in benign meningiomas--a possible predictor of malignancy

OBJECTIVE

It is known that p62 is a cytosolic conserved protein that binds non-covalently to ubiquitin. Expression of p62 has been seen in inclusions in neoplasias like hepatocellular and breast carcinomas but also in neuronal inclusions of degenerative brain disorders. Dysfunction of ubiquitin system leads to presence of p53 in cells suggested to be a predictor of future recurrence of meningioma.

MATERIAL

The study material included 45 benign meningiomas of postmenopausal women operated in Kuopio University Hospital between 1994 and 2002.

METHODS

Patterns of p62 immunopositivity in meningiomas was evaluated and the results were correlated to clinical and histological parameters.

RESULTS

Constant p62 labeling in at least each field measuring 1 mm in diameter was detected consisting of 5 different patterns. The most common labeling was seen in nuclear invaginations either as grains or homogenous labeling, followed by Marinesco like nuclear inclusions or rode like inclusions outside the invagination. In some cases cytoplasmic granular staining was seen. No correlation between different p62 patterns or extent of p62 expression, histological subtypes or proliferation marker Ki-67 was noted.

CONCLUSION

Our results indicate that in the benign not recurrent meningiomas, signs of functioning proteosomal system, can be detected using the p62 labeling. The function of proteosomal system in malignant and specifically invasive meningiomas needs to be further elucidated.

Absence of histological signs of tumor progression in recurrences of completely resected meningiomas

In meningioma recurrences a tumor progression has been proposed on a molecular genetic basis. From the histological point of view the problem has not been sufficiently investigated. Recurrences mainly depend on tumor location, histology, resection type and on the tumor growth in the adjacent nervous tissue. Seventy-six completely resected recurrent meningiomas have been studied. Most tumors were convexity or parasagittal meningiomas. The number of recurrences studied per tumor varied from 1 to 5. Besides histological methods, immunohistochemistry for Ki-67 MIB-1, TUNEL for apoptosis, counts of mitoses and molecular genetics for CDKN2A were performed. No variation of the mitotic index (MI) or MIB-1 labeling index (LI) was observed in recurrences. Histological features, the number of mitoses and the MIB-1 LI showed a great regional variability. Loss of heterozygosity (LOH) of CDKN2A was found to be slightly more frequent in the first recurrence than in the initial tumor, but it was lower in the following recurrences. The nervous tissue adjacent to the tumor could contain meningothelial cells and be responsible for recurrences. The number of mitoses appeared to be the most important criterion for establishing the tumor grade. The histological aspect does not change in recurrences and there is no progression. The greater number of recurrences in atypical and anaplastic tumors depends on their initial higher proliferation capacity. The occurrence of tumor meningothelial cells in the adjacent nervous tissue or in the thickened arachnoidal membrane can be responsible for recurrence.

Molecular genetics of meningiomas

In this article the authors provide a brief description of the current understanding of meningioma genetics. Chromosome 22 abnormalities, especially in the Neurofibromatosis Type 2 (NF2) gene, have been associated with meningioma development. Loss of heterozygosity of chromosome 22 occurs in approximately 60% of meningiomas; however, loss of NF2 gene function occurs in only one third of these lesions. This discrepancy supports the theory that a second tumor suppressor gene exists on chromosome 22, and the authors introduce several possible gene candidates, including BAM22, LARGE, INI1, and MN1 genes. Deletions of 1p have also been shown to correlate with meningioma progression. The genetic similarities and differences among sporadic, NF2-associated, pediatric, and radiation-induced meningiomas are discussed, with the observation that the nonsporadic meningiomas have a higher incidence of multiple chromosomal abnormalities at presentation. Ultimately, a better understanding of the molecular pathways of meningioma tumorigenesis will lead to new, successful treatments.

Breast Adenocarcinoma Metastatic to Epidural Cervical Spine Meningioma: Case Report and Review of the Literature

While several cases of cancer metastatic to cranial meningiomas have been reported, metastasis to spinal meningioma has been reported only once, and a mechanism for such metastases has not been investigated. We report a case of breast carcinoma metastatic to an epidural cervical meningioma, summarize the literature on metastases to central nervous system meningiomas, and suggest a possible mechanism. Our patient, a 55-year-old woman, presented with difficulty walking, back pain, and quadriparesis. Magnetic resonance imaging revealed an enhancing C3-4 epidural lesion and an L4 compression fracture. Because of concern that the fracture and epidural lesion might represent metastases, we performed a metastatic work-up, which revealed a right breast mass. The patient underwent C3-C4 laminectomies and an epidural lesion was encountered. Intraoperative frozen section revealed mixed meningioma and breast adenocarcinoma. A gross total resection was achieved and the patient subsequently received spinal irradiation and hormonal therapy. Whereas a literature review revealed numerous reports of metastases to cranial meningiomas, this represents only the second reported case of such pathology in the spine. Mechanisms of this unusual process likely include meningiomas' vascularity, meningiomas' slow growth providing nutrient availability, and perhaps, as suggested by our analysis, E-cadherin expression by both meningiomas and breast cancer. Metastasis to meningioma must be considered in an epidural spinal lesion in all patients with a known malignancy, with surgical aggressiveness tailored to the intraoperative pathologic diagnosis.

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.

Integrative genomic analysis identifies NDRG2 as a candidate tumor suppressor gene frequently inactivated in clinically aggressive meningioma

Although meningiomas are common central nervous system tumors, little is known about the genetic events responsible for malignant progression. In this study, we employed gene expression profiling to identify transcripts whose expression was lost in anaplastic (WHO grade III) versus benign (WHO grade I) meningioma. Approximately 40% of genes down-regulated in anaplastic meningioma were localized to chromosomes 1p and 14q. One specific gene located at 14q11.2, NDRG2, was consistently down-regulated in grade III meningioma, a finding which we validated at both the transcript and protein levels in independent sets of clinically and pathologically diverse meningiomas. Loss of NDRG2 expression was also seen in a subset of lower-grade meningiomas, including atypical meningiomas (WHO grade II) with clinically aggressive behavior. Furthermore, we found that the loss of NDRG2 expression was significantly associated with hypermethylation of the NDRG2 promoter. Collectively, these data identify NDRG2 as the first specific candidate tumor suppressor gene on chromosome 14q that is inactivated during meningioma progression. In addition, these findings highlight the utility of combining genomic, epigenetic, and expression data to identify clinically significant tumor biomarkers, and suggest that NDRG2 expression will be a useful and functionally relevant biomarker to predict aggressive behavior in patients with meningioma.

Metabolic differences between primary and recurrent human brain tumors: a 1H NMR spectroscopic investigation

High-resolution proton magnetic resonance spectroscopy was performed on tissue specimens from 33 patients with astrocytic tumors (22 astrocytomas, 11 glioblastomas) and 13 patients with meningiomas. For all patients, samples of primary tumors and their first recurrences were examined. Increased anaplasia, with respect to malignant transformation, resulting in a higher malignancy grade, was present in 11 recurrences of 22 astrocytoma patients. Spectroscopic features of tumor types, as determined on samples of the primary occurrences, were in good agreement with previous studies. Compared with the respective primary astrocytomas, characteristic features of glioblastomas were significantly increased concentrations of alanine (Ala) (p = 0.005), increased metabolite ratios of glycine (Gly)/total creatine (tCr) (p = 0.0001) and glutamate (Glu)/glutamine (Gln) (p = 0.004). Meningiomas showed increased Ala (p = 0.02) and metabolite ratios [Gly, total choline (tCho), Ala] over tCr (p = 0.001) relative to astrocytomas, and N-acetylaspartate and myo-inositol were absent. Metabolic changes of an evolving tumor were observed in recurrent astrocytomas: owing to their consecutive assessments, more indicators of malignant degeneration were detected in astrocytoma recurrences (e.g. Gly, p = 0.029; tCho, p = 0.034; Glu, p = 0.015; tCho/tCr, p = 0.001) in contrast to the comparison of primary astrocytomas with primary glioblastomas. The present investigation demonstrated a correlation of the tCho-signal with tumor progression. Significantly elevated concentrations of Ala (p = 0.037) and Glu (p = 0.003) and metabolite ratio tCho/tCr (p = 0.005) were even found in recurrent low-grade astrocytomas with unchanged histopathological grading (n = 11). This may be related to an early stage of malignant transformation, not yet detectable morphologically, and emphasizes the high sensitivity of 1H NMR spectroscopy in elucidating characteristics of brain tumor metabolism.

Meningiomas: report of a hospital-based registry

This is a hospital-based epidemiologic study of meningiomas. Of 1321 central nervous system tumours, meningiomas constituted 21% of the cases, being the second largest category of a single histologic type after astrocytomas. Of the 267 meningiomas studied, 247 were intra-cranial (92.5%). The age of the patients varied between 6 to 84 years. Histological subclassification is presented and treatment schedules discussed. 261 (98%) meningiomas were histologically benign and 5 were malignant meningiomas (1.9%). A 5-year follow-up was available in most cases, with the help of which it was possible to understand the biological behaviour of various sub-types and the influence of other parameters such as location and treatment schedules. Of note was the fact, that out of 261 patients with benign meningiomas, 11 succumbed in the immediate post-operative period and in 8 of these cases, the tumour was located at the base of the skull.

Positron emission tomography elucidates transport system and tumor proliferation in meningiomas

To test the in vivo transport system and tumor proliferation of meningiomas, in comparison with gliomas, 25 patients with meningiomas and 8 gliomas underwent quantitative kinetic analysis of ([18F])fluoro-2-deoxy-D-glucose (FDG) - positron emission tomography (PET) imaging and immunohistochemical study. Kinetic analysis was obtained by calculation of the rate constants: K1 (ml/g/min), which represents the transport of FDG from plasma to tissue; k2 (min(-1)), which demonstrates the transport back from tissue to plasma; and k3 (min(-1)), an indicator of glucose metabolism, using Gjedde's plot methods in a three-compartment model. Surgical specimens were evaluated by means of three different methods: i) immunoreactivity to vascular endothelial growth factor (VEGF) and glucose transporter-1 (Glut-1), representing the permeability of tumor vessels; ii) immunostaining for von Willebrand Factor (vWF), reflecting vascular surface areas of arterioles; and iii) the MIB-1 labeling index (MIB-1 LI), representing the proliferative potential. K1 was higher in meningiomas than in gliomas and was higher in atypical than in benign meningiomas. k3 was correlated with MIB-1 LI in meningiomas, but not in gliomas. Immunohistochemically, meningiomas were less reactive to VEGF or Glut-1 than gliomas but atypical meningiomas stained more intensely than benign meningiomas. The vascular surface area was significantly larger in meningiomas than in gliomas and atypical meningiomas had high values for both permeability and surface area than benign meningiomas. High values for K1 and k3 indicate the aggressive proliferation of meningiomas and, in atypical meningiomas, the synergistic interaction of the high permeability and the large surface area yielded conditions conducive to glucose metabolism and tumor proliferation. Evaluation of K1 and k3 facilitates to predict the tumor aggressiveness and to optimize the surgical management.

Recurrent solitary fibrous tumour in the cerebellopontine angle

Solitary fibrous tumours (SFT) of the central nervous system are rare. They resemble meningioma in clinical presentation, imaging features and appearance at surgery. Schwannoma, hemangiopericytoma and other spindle cell mesenchymal neoplasms should also be considered in the differential diagnosis. Although the histogenesis of this tumour is still debated, strong CD34 reactivity of the tumour cells suggests that SFT is mesenchymal. We present the clinical, radiological, and pathological features of an SFT located in the cerebellopontine angle (CPA). A 55-year-old female presented with 6 months of headache. The MRI scan showed a contrast enhancing ovoid mass in the left CPA. At craniotomy, the tumour was completely resected. Histolopathological diagnosis was of meningioma. Three years later, the symptoms recurred and an MRI scan demonstrated tumour recurrence. A repeat craniotomy was performed and the lesion was again completely excised. Tumour morphology on histopathology and immunoreactivity for CD34 of the tumour cells supported the diagnosis of SFT. Review of the original tumour also disclosed immunoreactivity for CD34. Ki67 labeling indices were less than 1% in both tumours.

Contralateral meningeal artery supply of paramedian meningiomas

BACKGROUND

When resecting at falcine or parasagittal portion of paramedian meningiomas, intraoperative hemostasis often is difficult despite effective management of ipsilateral meningeal arteries. We attribute such difficulties to meningeal artery blood supply from the contralateral side. We retrospectively studied feeding arteries from both sides in case of paramedian meningioma in terms of patient and tumor characteristics.

METHODS

Forty-three patients with paramedian meningiomas underwent selective internal and external carotid angiography. We investigated how contralateral meningeal arterial feeders related to patient profiles and imaging, histopathologic, and immunohistochemical findings.

RESULTS

Contralateral meningeal supply existed for 14 of 25 falcine meningiomas and 6 of 18 parasagittal meningiomas. Patients with contralateral feeders were 8.5 years younger than the others (P=.027) and were more likely to have larger tumors (P=.028). These were histopathologically malignant (P=.048), while showing more proliferation followed by monoclonal antibody against the Ki-67 antigen index (P=.012) and angiogenetic potential associated with vascular endothelial growth factor expression (P=.0085).

CONCLUSIONS

Contralateral meningeal supply may reflect strong angiogenetic recruitment from rapid tumor growth followed by high expression of vascular endothelial growth factor. This angiographical feature may predict the aggressive growth of paramedian meningiomas.

Correlation between histological grade and MIB-1 and p53 immunoreactivity in meningiomas

OBJECTIVE

Meningiomas for the most part are slow-growing benign tumors, but complete removal can be difficult and recurrence is an issue. The aim of this study was to re-evaluate tumors diagnosed as meningioma previously in our hospital, according to the latest World Health Organization classification. We also examined the relationships among parameters such as brain invasion, histological grade and Ki-67 and p53 expression in these tumors.

MATERIALS AND METHODS

Meningioma biopsy specimens numbering 60 (48 grade I, 11 grade II, and 1 grade III tumors) were examined immunohistochemically using monoclonal antibodies for Ki-67 (MIB-1) and p53 protein. The MIB-1 labeling index (LI) for each tumor was calculated as a percentage based on the number of stained cells per total cells counted. The level of p53 expression in each sample was semiquantatively evaluated as < 1%, 1 - 10%, 10 - 70%, or > 70%. Any value > 1% was accepted as presence of p53 expression.

RESULTS

Of the 60 meningiomas, 7 (11.7%) exhibited brain invasion. The mean MIB-1 LI values for the grade I and grade II tumors were 1.1% and 2.3%, respectively. The corresponding levels of p53 protein expression in these groups were 54.1% and 72.7%. The MIB-1 LI and the level of p53 expression in the one grade III meningioma were 6.7% and 10 - 70%, respectively. Histological grade was significantly correlated with MIB-1 LI and with p53 expression (p < 0.01 for both). Brain invasion was not correlated with histological grade, MIB-1 LI, or p53 expression.

CONCLUSION

The results indicate that MIB-1 LI and p53 protein expression are good indicators of histological grade in meningioma and may be particularly valuable for distinguishing borderline atypical meningiomas. The number of cases was limited, but the findings also suggest that brain invasion is a prognostic parameter independent of grade, MIB-1 LI and p53 expression.

Intracerebral schwannoma clinically and radiologically mimicking meningioma

A case of intracerebral schwannoma (ICS) occurring in a 33-year-old woman is presented. The patient's history of headache, numbness, tingling and the recent development of weakness of the right upper extremity with right facial droop began during pregnancy. Magnetic resonance imaging (MRI) showed a 4 x 2 x 2 cm heterogeneous, gadolinium-enhanced mass at the left frontoparietal junction, with peritumoral edema and a dural-based attachment. During her pregnancy, the mass increased in size. The surgically resected specimen consisted of lobulated, somewhat gelatinous soft tissue. Microscopically, the tumor demonstrated classic biphasic Antoni type A and B patterns, admixed with degenerative changes. Immunohistochemically, the neoplastic cells were positive for S-100 protein (diffuse and strong), CD34 (primarily in Antoni B areas), glial fibrillary acidic protein (GFAP; weak and diffuse) and calretinin (mainly in Antoni A areas), while none was positive for CD31, estrogen and progesterone receptors, bcl-2, or epithelial membrane antigen (EMA). Ultrastructurally, basal laminae and Luse bodies were identified. The differential diagnosis includes fibrous meningioma, solitary fibrous tumor, and ICS. Twenty-seven cases of ICS were reviewed in which the histological diagnosis was confirmed immunohistochemically or ultrastructually, and the cases were summarized (including the present case). A combined use of immunostains (S-100 protein, EMA, CD34, and maybe calretinin) is of great help in distinguishing ICS from its histological mimickers.

INI1 expression is retained in composite rhabdoid tumors, including rhabdoid meningiomas

Rhabdoid cells are encountered in specific entities, such as malignant rhabdoid tumor and atypical teratoid/rhabdoid tumor, as well as in composite rhabdoid tumors derived secondarily from other tumor types. Although rhabdoid tumors are uniformly aggressive, distinction of the entity from the phenotype remains important for its therapeutic implications. The majority of malignant rhabdoid tumors and atypical teratoid/rhabdoid tumors affect infants and young children, harbor chromosome 22q deletions, and inactivate the INI1/hSNF5/BAF47 tumor suppressor gene on 22q11.2. In contrast, most composite rhabdoid tumors are diagnosed in adults, with FISH detectable 22q losses the exception rather than the rule. However, this assay remains limited since 22q dosages are maintained in 20-30% of malignant rhabdoid tumors and atypical teratoid/rhabdoid tumors. Furthermore, chromosome 22 losses are common in some parent tumor types, particularly meningiomas. The recently developed INI1 antibody shows loss of nuclear expression in malignant rhabdoid tumors and atypical teratoid/rhabdoid tumors, though its status in composite rhabdoid tumors is largely unknown. Therefore, we utilized immunohistochemistry and FISH to study INI1 expression and 22q dosages, respectively, in 40 composite rhabdoid tumors, including 16 meningiomas, 15 carcinomas, three melanomas, two sarcomas, two glioblastomas, and 1 neuroblastoma. Approximately 70% of rhabdoid meningiomas had a 22q deletion, but this was rare in other tumor types. Except for one retroperitoneal leiomyosarcoma, nuclear INI1 expression was retained in all composite rhabdoid tumors, including meningiomas with 22q deletion. Therefore, we conclude that INI1 immunohistochemistry is a relatively simple, sensitive, and specific technique for distinguishing malignant rhabdoid tumor and atypical teratoid/rhabdoid tumor from composite rhabdoid tumor.

Meningiomas expressing and responding to cholecystokinin (CCK)

The effect of cholecystokinin (CCK) on cultured human meningioma derived cells was investigated. Exposure of meningioma cells for 6-12 days to CCK-8s (2-200 nM) resulted in a dose dependent stimulation of cell growth to a maximum of 1.1-fold over basal controls. A time course study showed stimulation of cell growth at day 3 followed by increase throughout day 6. The stimulatory effect of CCK on meningioma cell growth was completely abolished by a CCK-B specific receptor antagonist, L-365,260. Reverse-transcription of meningioma-derived RNA into cDNA followed by amplification by the polymerase chain reaction using specific primers for CCK peptide and its CCK-A and/B receptor revealed 100% presence of CCK peptide and CCK-B receptors mRNA whereas CCK-A receptor was expressed in 66% of the meningiomas. These results provide evidence that human meningioma cells possess CCK peptide and its receptors the activation of which leads to increase of cell growth possibly via an autocrine/paracrine mechanism.

Prognostic significance of Ki-67/MIB-1 proliferation index in meningiomas

Even though tumor grade, subtype, and extent of resection are strong prognostic factors in human meningiomas, the growth of this tumor is still unpredictable, and additional prognostic markers are needed. Thus, immunohistochemical determination of proliferative activity using the Ki-67 equivalent antibody MIB-1 has gained increased attention. However, the reported prognostic significance of this marker in meningiomas is not fully clarified. The aim of this study was to investigate the prognostic role of MIB-1 proliferation index (PI) in a series of meningiomas comprising 23 benign, 17 atypical, and 9 anaplastic tumors. MIB- 1 PI increased with increasing tumor grade and discriminated significantly benign from atypical and anaplastic meningiomas whereas no difference was found between the latter two grades. However, due to the considerable overlap of PI values between the various grades, one should be circumspect before using this criterion for tumor grading. Furthermore, MIB-1 PIs were significantly higher in recurrent tumors compared with non-recurrent and a reliable MIB-1 PI cut-off value of 10% was established. This value, however, cannot automatically be adapted by other laboratories and must be regarded just as a guideline. In conclusion, MIB-1 PI appears as an important prognostic factor and should be used in combination with traditional histological criteria for malignancy in order to identify meningiomas with increased risk of recurrence.

Bcl2 and ROS1 expression in human meningiomas: an analysis with respect to histological subtype

Tumors of the central nervous system account for approximately 9% of all primary neoplasm in humans, while tumors of covering elements, the meninges, account for 13-19% and constitute the second largest group of brain tumors. These are known to exhibit a variety of chromosomal abnormalities besides change in the expression level of certain oncogenes. Among oncogenes, bcl2, an anti-apoptotic factor and ROS1 that encodes a protein with a structure similar to the epidermal growth factor (EGF) and insulin receptor and has a tyrosine kinase activity, have been shown to be associated with many malignant tumors. In the present study we have analysed the expression of bcl2 using immuno-histochemistry and ROS1 expression by reverse-transcription coupled with polymerase chain reaction (RT-PCR) of the transcript using primers specific for the intra-cellular domain and then tried to correlate the findings with the subtype of the meningioma defined on the basis of histology. Out of the six bcl2 positive cases in our study, there were three transitional tumors, two fibroblastic and one recurrent meningioma subtype. bcl2 seemed to be more consistently expressed in the cytoplasm of spindle cell component of meningiomas. Thirteen meningiothelial meningiomas did not show any staining for bcl2. ROS1 gene expression could be detected in 4 tumors all of those were Grade-I meningothelial meningiomas. One of the malignant meningioma included in the study was clearly negative for bcl2 as well as ROS1. Thus bcl2 and ROS1 oncogene expression in meningiomas are not concurrent and neither can be ascribed to any histologic subtype or grade of tumor.

Meningioma growth and interferon beta-1b treated multiple sclerosis: coincidence or relationship?

Although the coincidence of multiple sclerosis (MS) and central nervous system (CNS) tumors has been reported in over 30 cases in English literature, meningioma growth was associated with interferon-beta (INF-b) treated MS only in two of them. We report the case of a 19-year-old woman with clinically possible, laboratory supported MS, and a concomitant right intraventricular tumor with magnetic resonance imaging (MRI) characteristics consistent with meningioma (similar signal with grey matter on T1 and T2-weighted images and homogenous, intense enhancement). Two years after initiation of INF-b treatment, follow-up brain MRI revealed enlargement of the intraventricular mass and relative increase in the number of white matter lesions without significant clinical deterioration. She underwent almost total resection of the mass and histology confirmed the diagnosis of papillary meningioma. Based on the immunohistochemistry results, we speculate that INF-b resulted in meningioma growth by enhancing platelet derived growth factor (PDGF) receptors or/and down-regulating transforming growth factor receptors on the tumor itself.

Meningioma Transcript Profiles Reveal Deregulated Notch Signaling Pathway

Meningiomas constitute the second most common central nervous system tumor, and yet relatively little is known about the molecular events that are important for the pathogenesis and malignant progression of these tumors. We have used serial analysis of gene expression to compare the transcriptomes of nonneoplastic meninges and meningiomas of all malignancy grades. A novel finding from this screen is the induction of three components of the Notch signaling pathway: the transcription factor, hairy and enhancer of Split1 (HES1) and two members of the Groucho/transducin-like enhancer of Split family of corepressors, TLE2 and TLE3. TLE corepressors interact and modulate the activity of a wide range of transcriptional regulatory systems, one of which is HES1. We have shown that the transcript and protein levels of HES1, the Notch2 and Notch1 receptors and the Jagged1 ligand are induced in meningiomas of all grades, whereas induction of TLE2 and TLE3 occurs specifically in higher-grade meningiomas. Meningioma cell lines express components of the Notch signaling pathway and an inhibitor of this pathway suppresses meningioma cell survival. These results suggest that deregulated expression of the Notch pathway is a critical event in meningioma pathogenesis and that modulation of this and potentially other signaling pathways by TLE corepressors leads to a more malignant phenotype.

Meningothelial hyperplasia: a detailed clinicopathologic, immunohistochemical and genetic study of 11 cases

Meningothelial hyperplasia is a poorly characterized entity, often associated with advanced age, chronic renal failure, trauma, hemorrhage, and neoplasia. In order to elucidate the nature of this lesion, 11 cases defined by the presence of nests of 10 or more cell layers thick, were compared with normal arachnoidal cap cells and meningiomas. Immunohistochemistry and FISH were performed to determine NF2 (merlin), protein 4.1B, EMA, progesterone receptor (PR), EGFR, survivin, VEGF, PDGF-BB, PDGFR-beta, E-cadherin, and cathepsin D status. All cases had at least one putative predisposing factor, including hemorrhage (7), chronic renal disease (5), old age (5), trauma (1), and an adjacent optic nerve pilocytic astrocytoma (1). There was typically a discontinuous growth pattern, with no invasion of surrounding normal tissue. No gene deletions were found, though scattered polyploid cells were seen in 2 cases. The immunoprofile was similar to normal cap cells with one exception; whereas normal cells were uniformly negative for PR, nuclear positivity was seen in 64% of hyperplasias, a frequency similar to that of benign meningiomas. Our data suggest that meningothelial hyperplasia is a reactive process that is usually distinguishable from meningioma based on clinicopathologic and genetic features. It may be preneoplastic in some, though further studies are needed to test this hypothesis.

Expression of Urokinase-Type Plasminogen Activator Receptor (uPAR) in Primary Central Nervous System Neoplasms

The cellular receptor for urokinase-type plasminogen activator receptor (uPAR) is a member of the glycosylphosphatidylinositol (GPI) anchored protein family. It is a specific cell surface receptor for its ligand, urokinase-type plasminogen activator, which catalyzes the formation of plasmin from plasminogen to generate the proteolytic cascade and leads to the breakdown of the extracellular matrix. uPAR has been shown to correlate with a propensity to tumor invasion and metastasis in several types of non-central nervous system tumors. In this study, the authors examined the immunohistochemical expression of uPAR in 65 primary brain tumors (5 pilocytic astrocytomas, 5 diffuse astrocytomas, 6 anaplastic astrocytomas, 8 glioblastomas, 5 oligodendrogliomas, 4 oligoastrocytomas, 6 anaplastic oligoastrocytomas, 4 gangliogliomas, 4 ependymomas, 5 medulloblastomas, 6 schwannomas, 5 meningiomas, 2 atypical meningiomas). The specimens were evaluated for intensity of immunostaining (0-3 scale), cellular localization of staining, and specific or unique patterns of staining. Some degree of uPAR expression was observed in all tumors. A significant positive correlation (P = 0.0006) between tumor grade and staining intensity was identified within the astrocytoma/glioblastoma subgroup, suggesting a possible correlation with anaplastic change and propensity to tumor invasion. Expression of uPAR in nonmalignant, noninvasive tumors such as schwannoma and meningioma suggests that uPAR may have other biologic functions in addition to promotion of tumor invasion.

Endocannabinoid metabolism in human glioblastomas and meningiomas compared to human non-tumour brain tissue

The endogenous levels of the two cannabinoid receptor ligands 2-arachidonoyl glycerol and anandamide, and their respective congeners, monoacyl glycerols and N-acylethanolamines, as well as the phospholipid precursors of N-acylethanolamines, were measured by gas chromatography-mass spectrometry in glioblastoma (WHO grade IV) tissue and meningioma (WHO grade I) tissue and compared with human non-tumour brain tissue. Furthermore, the metabolic turnover of N-acylethanolamines was compared by measurements of the enzymatic activity of N-acyltransferase, N-acylphosphatidylethanolamine-hydrolysing phospholipase D and fatty acid amide hydrolase in the same three types of tissue. Glioblastomas were characterized by enhanced levels of N-acylethanolamines (eightfold, 128 +/- 59 pmol/micromol lipid phosphorus) including anandamide (17-fold, 4.6 +/- 3.1 pmol/micromol lipid phosphorus) and several species of N-acylphosphatidylethanolamines (three to eightfold). This was accompanied by a more than 60% reduction in the enzyme activities of N-acylphosphatidylethanolamine-hydrolysing phospholipase D and fatty acid amide hydrolase. By contrast, meningiomas were characterized by a massively enhanced level of 2-monoacyl glycerols (20-fold, 2293 +/- 361 pmol/micromol lipid phosphorus) including 2-arachidonoyl glycerol (20-fold, 1524 +/- 361 pmol/micromol lipid phosphorus). This was accompanied by an enhanced in vitro conversion of phosphatidylcholine to monoacyl glycerol (fivefold). The enhanced level of the 2-arachidonoyl glycerol, anandamide and other N-acylethanolamines detected in the two types of tumour tissue may possibly act as endogenous anti-tumour mediators by stimulation of both cannabinoid and non-cannabinoid receptor-mediated mechanisms.

Sex steroid and growth factor profile of a meningioma associated with pregnancy

BACKGROUND

Increased growth of meningiomas during pregnancy as well as postpartum clinical regression of symptoms have been reported but remain poorly understood. A better understanding of the factors that contribute to these observations, including potential factors associated with pregnancy, could enable design of more effective adjuvant therapies.

METHODS

We describe the presentation of a meningioma during the immediate postpartum period. Serial imaging demonstrated subsequent rapid decrease in size of the tumour prior to any intervention. The lesion was resected, and the tissue was subjected to immunostaining for gene products associated with pregnancy, including estrogen receptor (ER), progesterone receptor (PR), platelet-derived growth factor receptor B (PDGFRB), fibroblastic growth factor receptor 2 (FGFR-2), epidermal growth factor receptor (EGFR) and human placental lactogen (hPL).

RESULTS

The lesion proved to be an atypical fibroblastic meningioma grade II (WHO). Immunostaining demonstrated significant staining for PR, PDGFRB, and FGFR-2. No specific staining for ER, EGFR, or hPL was identified.

CONCLUSION

Although clinical regression of meningioma following pregnancy is well-recognized, imaging data are much less abundant. This report provides clear clinical and imaging documentation of a meningioma associated with pregnancy. In addition, the growth factor profile of this tumour suggests the importance of PR, PDGFRB, and FGFR-2 as potential therapeutic targets.

Characterization of 68Ga-DOTA-D-Phe1-Tyr3-octreotide kinetics in patients with meningiomas

Because biopsy has a high risk of hemorrhage and the findings of CT and MRI are often ambiguous, especially at the base of the skull, additional methods for the characterization of intracranial tumors are needed. Meningiomas show high expression of the somatostatin receptor subtype 2 and thus offer the possibility of receptor-targeted imaging. We used the somatostatin analog (68)Ga-DOTA-d-Phe(1)-Tyr(3)-octreotide (DOTA-TOC) labeled with the positron emitter (68)Ga (half-life, 68 min), obtained from a (68)Ge/(68)Ga generator, for PET of these tumors. In contrast to (18)F-FDG, this ligand shows high meningioma-to-background ratios. The aim was to evaluate kinetic parameters in meningiomas before radiotherapy.

METHODS

Dynamic PET scans (3-dimensional mode; 28 frames; ordered-subsets expectation maximization reconstruction) were acquired for 21 patients (mean age +/- SD, 51 +/- 13 y) before radiotherapy during the 60 min after intravenous injection of 156 +/- 29 MBq of (68)Ga-DOTA-TOC. We analyzed 28 meningiomas (median grade [I] according to the system of the World Health Organization) with volumes of at least 0.5 mL (mean volume, 13.1 mL) and nasal mucosa as reference tissue, showing a slight to moderate physiologic uptake. For evaluation of the (68)Ga-DOTA-TOC kinetics, the vascular fraction (vB) and the rate constants (k1, k2, k3, and k4 [1/min]) were computed using a 2-tissue-compartment model. Furthermore, receptor binding (RB) (k1 - k1 x k2) and the ratios k1/k2 and k3/k4 were calculated.

RESULTS

Significant differences (P < 0.05; t test) between meningiomas and the reference tissue were found for the mean standardized uptake value (10.5 vs.1.3), vB (0.42 vs. 0.11), k2 (0.12 vs. 0.56), k3 (0.024 vs. 0.060), k4 (0.004 vs. 0.080), and RB (0.49 vs. 0.13). Although there was no significant difference for k1 (0.54 vs. 0.40), the ratios k1/k2 (4.50 vs. 0.71) and k3/k4 (6.00 vs. 0.75) were markedly greater in meningiomas than in reference tissue.

CONCLUSION

The high uptake of (68)Ga-DOTA-TOC in meningiomas can be explained by the high values for vB and by the remarkably low values for k2 and k4, leading to significantly greater k1/k2 and k3/k4 ratios and RB in meningiomas than in reference tissue. Thus, pharmacokinetic modeling offers a more detailed analysis of biologic properties of meningiomas. In further studies, these data might serve as a basis for monitoring the somatostatin receptors of meningiomas after radiotherapy.

Rac2 expression and mutation in human brain tumors

BACKGROUND

Rac1 and Rac2 are interchangeable in NADPH oxidase activation. Rac1 plays an important role in regulating nuclear signalling and in the activation of transcriptional factors that regulate gene expression and cell growth. Our previous study observed mutation in effector region of Rac1 gene in brain tumors. Little is known about the expression and mutation of Rac2 in human brain tumors.

METHOD

We examined the expression of Rac2 by using reverse transcriptase-polymerase chain reaction (RT-PCR) and northern blot analysis and the mutation of Rac2 gene by using DNA sequence analysis.

FINDINGS

The decreased expression of Rac2 was found in 15 cases (57.7%) including 8 of 10 astrocytomas, 2 of 8 meningiomas, and 5 of 8 pituitary adenomas. Two of 13 cases with decreased expression of Rac2 had gene mutation. Only two of 26 cases had Rac2 overexpression in which no Rac2 gene mutation was found. Four of 8 cases with normal Rac2 expression had Rac2 gene mutation. The site of Rac2 gene mutation had no hot spots and was not concentrated in the effector region.

CONCLUSIONS

Our results showed a low frequency of mutation and no hot spots of mutation in Rac2 gene in brain tumors, suggesting a decreased possibility of Rac2 in the brain tumorigenesis. The role of high frequency of decreased Rac2 expression in brain tumors, particularly in malignant astrocytomas, needs further investigations to be elucidated.

Clear cell meningioma: case report and review of the literature

Clear cell meningioma (CCM) is a rare variant of meningioma. Only 17 cases have been previously reported in children. Although it has bland cytologic features, it has a higher rate of recurrence than does conventional meningioma. This variant has been reported in sites such as spinal/intradural (lumbar and thoracic), cerebellopontine angle, and supratentorial. The differential diagnosis of CCM includes microcystic meningioma, hemangioblastoma, and clear cell ependymoma. The characteristic histology and immunohistochemistry leads to the diagnosis. We present a case of a 7-year-old boy with a CCM of the cauda equina and a review of pediatric CCM.

Insights into meningioangiomatosis with and without meningioma: a clinicopathologic and genetic series of 24 cases with review of the literature

Meningioangiomatosis (MA) is a rare seizure-associated lesion of presumed hamartomatous or developmental origin. It is occasionally combined with a neoplasm, most commonly meningioma (MA-M). In the current study, we examined 24 cases (14 pure MA, 10 MA-M) using immunohistochemistry for merlin, protein 4.1 B, progesterone receptor (PR), and MIB-1, as well as FISH for NF2 and 4.1B gene dosages. Nine cases of MA-M (90%) had gene deletions (NF2/4.7B), protein losses (merlin/protein 4.1B), and/or PR positivity, with a similar or identical phenotype in both components. No PR positivity or gene deletions were seen in pure MAs, though merlin and/or protein 4.1B were immunonegative in six cases. Our data suggest that in most MA-Ms, the MA component is neoplastic, likely representing an exuberant perivascular pattern of spread from the meningioma, rather than an underlying hamartoma. This pattern of spread may be facilitated by meningiomas that are predominantly leptomeningeal or intracerebral in origin. It remains important to distinguish this pattern from true brain invasion, given the more ominous prognostic significance of the latter. In contrast, most perivascular spindled cells of pure MA are genetically and immunohistochemically similar to non-neoplastic meningothelial cells, consistent with current histogenetic theories.

Reproductive and hormonal factors and risk of brain tumors in adult females

Causes of brain tumors are largely unknown, and there is an urgent need to identify possible risk factors. Several observations point to a possible role of reproductive hormones, but few epidemiologic studies have examined whether reproductive factors, such as age at menarche and parity, are associated with brain tumor risk. We conducted a multi-center case-control study of newly diagnosed glioma (n = 212) and meningioma (n = 151) and frequency-matched controls (n = 436) in women from hospitals in Phoenix, Arizona; Boston, Massachusetts; and Pittsburgh, Pennsylvania between 1994 and 1998. Research nurses interviewed patients regarding potential risk factors for brain tumors, including reproductive factors and hormone use. Unconditional logistic regression analyses were used to calculate odds ratios (ORs) and 95% confidence intervals (CIs). Risk of glioma increased with older age at menarche [OR = 1.90 (95% CI = 1.09-3.32) for age at menarche > or =14 vs. <12 years]. Early age at first birth was associated with reduced risk of glioma [OR = 0.43 (95% CI = 0.23-0.83) for a first birth before age 20 vs. nulliparity], but there was little effect of number of births. Exogenous hormone use was also associated with a lower risk of glioma, but risks did not vary systematically according to duration of use or age at first use. Possibly owing to low statistical power, there were few noteworthy associations between meningioma and reproductive factors, other than a nonsignificant (p = 0.09) trend of increasing risk with increasing age at menopause. The findings suggest that hormonal exposures early in life may be associated with risk of glioma, but the evidence is inconsistent and does not point clearly to a specific causal or protective hypothesis.

Gamma knife radiosurgery in skull base meningiomas: a possible relationship between somatostatin receptor decrease and early neurological improvement without tumour shrinkage at short-term imaging follow-up

BACKGROUND

This study investigates a possible relationship between the effects of gamma knife (GK) on meningioma somatostatin receptors (SRs) and the high rate of early neurological improvement without tumour reduction at short-term imaging follow-up.

METHODS

From December 1997 to December 2002, somatostatin receptor scintigraphy (SRS) using an 111Indium-labelled somatostatin analogue, Octreotide, was performed both before and 7-12 months after radiosurgery in 20 patients with intracranial meningiomas. Semiquantitative data were calculated as an SRS index.

FINDINGS

The pre-GK SRS index was always > 1, averaging 4.44 +/- 3.20. There were no statistically significant differences between the pre-GK average values of primary (4.80 +/- 3.65) and residual (3.75 +/- 1.93) meningiomas. At the first clinical/MRI follow-up, the neurological examination had improved in 15/20 (75%) and had not changed in 5/20 patients. A corresponding slight tumour shrinkage on high-resolution MRI was documented in 3/20 cases only. The post-GK average SRS index was lower than pre-GK values both in primary (3.87 +/- 3.19) and in adjuvant (2.52 +/- 1.14) treatments, but the differences were not significant. However, the subgroup of patients with early neurological improvement showed a higher pre-GK average SRS index (5.21 +/- 3.33) and a more substantial post-GK average SRS index decrease (3.86 +/- 3.00) than the patients whose clinical condition remained stable (2.10 +/- 0.59 and 1.99 +/- 0.55, respectively). The difference between the two subgroups of patients proved to be statistically significant (P < 0.05).

CONCLUSIONS

Our preliminary findings suggest a possible relationship between a decrease in the concentration of SRs on meningioma cells at short-term functional imaging follow-up after radiosurgery and early neurological improvement.

Expression of the gene for hematopoietic cell specific protein is not restricted to cells of hematopoietic origin

Hematopoietic cell line specific protein (HS1) is an intracellular signaling protein that has been reported as specifically expressed in hematopoietic cells. HS1 is known as a major substrate of protein-tyrosine kinases following activation by B-cell or T-cell receptor complexes. We report the first evidence that HS1 is also expressed in a variety of tissues different from hematopoietic tissues by using sensitive expression analysis including real-time quantitative RT-PCR. While former studies on HS1-expression were mostly limited to cells of hematopoietic origin, we screened a larger number of human tissues including tumor samples. Normal lung tissue showed a high degree of HS1 expression, second to the expression of hematopoietic cells. Expression of HS1 in tumor tissues was also clearly detectable. Our findings suggest that the signaling protein HS1 is involved in pathways different from the ones that have a specific role in the intracellular processes of hematopoietic cells.