Histological subtypes and prognostic problems in meningiomas

Malignant Transformation of Meningioma With TERT Promoter Mutation: A Case Report

High-grade meningiomas make up a relatively minor proportion of meningiomas, which are one of the most common types of primary intracranial tumors in adults. Though rare, a considerable portion of high-grade meningiomas arise from malignant transformation of benign meningiomas. The 2021 World Health Organization (WHO) classification criteria introduced molecular markers in the diagnosis and grading of central nervous system (CNS) tumors and assigned certain genomic mutations to grade 3 meningiomas. We report a case of a 54-year-old male patient who underwent stepwise malignant transformation of meningioma from WHO grade 1 to grade 3 within 10 years, during the course of five surgeries followed by adjuvant stereotactic radiosurgery and radiotherapy. We performed next-generation sequencing (NGS) on the most recent grade 3 meningioma specimen and found that it carried a telomerase reverse transcriptase promoter (TERTp) mutation (c.-124C>T) in accordance with the 2021 WHO criteria for grade 3 meningiomas. We then retrospectively examined the previous grade 1 and 2 specimens and found them to have the same mutation. We reviewed the significance of molecular markers in the diagnosis of meningiomas, possible genetic alterations associated with their malignant transformation, and what measures could be taken to effectively manage meningiomas considering NGS findings.

High expression of GSKIP is associated with poor prognosis in meningioma

Meningiomas are the most common extra-axial primary central nervous system tumors. There is no effective treatment or targeted therapy for meningioma except excision and radiotherapy. glycogen synthesis kinase 3β interaction protein (GSKIP) is an A-kinase anchor protein that has cytosolic scaffolding function and binds to a protein kinase A and glycogen synthesis kinase 3β to modulate different biological processes and malignant tumorigenesis through the Wnt pathway. The purpose of this study was to investigate the relationship between GSKIP expression and the clinico-pathological parameters in meningioma using immunohistochemical staining. We collected samples from 74 patients, from 2008 to 2012, in the Kaohsiung Medical University Hospital that had data on the staging and prognosis of the meningioma pathological section. Chi-square, Kaplan-Meier method, and cox regression were used to analyze the correlation between clinical parameters and immunohistochemistry staining for GSKIP. Following our immunohistochemical score, we found that higher expression of GSKIP was associated with high World Health Organization grading, recurrence, malignant transformation, and reduced overall survival time and recurrence-free survival time in meningioma. GSKIP may be a biomarker of poor prognosis and a target protein for therapy in meningioma.

Clinical Implications of the Mitotic Index as a Predictive Factor for Malignant Transformation of Atypical Meningiomas

Objective

Intracranial atypical meningiomas have a poor prognosis and high rates of recurrence. Moreover, up to one-third of the recurrences undergo high-grade transformation into malignant meningiomas. We aimed to investigate the clinical factors that can predict the propensity of malignant transformation from atypical to anaplastic meningiomas.

Methods

Between 2001 and 2018, all patients with atypical meningioma, in whom the tumors had undergone malignant transformation to anaplastic meningioma, were included. The patients' medical records documenting the diagnosis of atypical meningioma prior to malignant transformation were reviewed to identify the predictors of transformation. The control group comprised 56 patients with atypical meningiomas who were first diagnosed between January 2017 and December 2018 and had no malignant transformation.

Results

Nine patients in whom the atypical meningiomas underwent malignant transformation were included. The median time interval from diagnosis of atypical meningioma to malignant transformation was 19 months (range, 7-78). The study group showed a significant difference in heterogeneous enhancement (77.8% vs. 33.9%), bone invasion (55.6% vs. 12.5%), mitotic index (MI; 14.8±4.9 vs. 3.5±3.9), and Ki-67 index (20.7±13.9 vs. 9.5±7.1) compared with the control group. In multivariate analysis, increased MI (odds ratio, 1.436; 95% confidence interval, 1.127-1.900; p=0.004) was the only significant factor for predicting malignant transformation.

Conclusion

An increased MI within atypical meningiomas might be used as a predictor of malignant transformation. Tumors at high risk for malignant transformation might require more attentive surveillance and management than other atypical meningiomas.

Does post-operative radiotherapy improve the treatment outcomes of intracranial hemangiopericytoma? A retrospective study

BACKGROUND

Intracranial hemangiopericytoma is a rare disease and surgery is the mainstay treatment. Although postoperative adjuvant radiotherapy is often used, there are no reports comparing different radiotherapy techniques. The purpose of this study is to analyze the impact of post-operative radiotherapy and different radiotherapy technique on the results in patients with intracranial hemangiopericytoma (HPC).

METHODS

We retrospectively reviewed 66 intracranial HPC patients treated between 1999 and 2019 including 29 with surgery followed by radiotherapy (11 with intensity-modulated radiotherapy (IMRT) and 18 with stereotactic radiosurgery (SRS)) and 37 with surgery alone. Chi-square test was used to compare the clinical characteristic between the groups. The Kaplan-Meier method was used to analyze overall survival (OS) and recurrence-free survival (RFS). Multivariate Cox proportional hazards models were used to examine prognostic factors of survival. We also underwent a matched-pair analysis by using the propensity score method.

RESULTS

The crude local control rates were 58.6% in the surgery plus post-operative radiotherapy group (PORT) and 67.6% in the surgery alone group (p = 0.453). In the subgroup analysis of the PORT patients, local controls were 72.7% in the IMRT group and 50% in the SRS group (p = 0.228). The median OS in the PORT and surgery groups were 122 months and 98 months, respectively (p = 0.169). The median RFS was 96 months in the PORT group and 72 months in the surgery alone group (p = 0.714). Regarding radiotherapy technique, the median OS and RFS of the SRS group were not significantly different from those in the IMRT group (p = 0.256, 0.960). The median RFS were 112 and 72 months for pathology grade II and III patients, respectively (p = 0.001). Propensity score matching did not change the observed results.

CONCLUSION

In this retrospective analysis, PORT did not improve the local control rates nor the survivals. The local control rates after IMRT and SRS were similar even though the IMRT technique had a much higher biological dose compared with the SRS technique.

Malignant Progression Contributes to the Failure of Combination Therapy for Atypical Meningiomas

Objective

To investigate the independent risk factors for recurrence in intracranial atypical meningiomas (AMs) treated with gross total resection (GTR) and early external beam radiotherapy (EBRT).

Methods

Clinical, radiological, and pathological data of intracranial AMs treated with GTR-plus-early-EBRT between January 2008 and July 2016 were reviewed. Immunohistochemical staining for Ki-67 was performed. Kaplan–Meier curves and univariate and multivariate Cox proportional hazards regression analyses were used to explore independent predictors of tumor recurrence. Chi square test was performed to compare variables between subgroups.

Results

Forty-six patients with intracranial AMs underwent GTR and early EBRT. Ten (21.7%) recurred and three (6.5%) died during a median follow-up of 76.00 months. Univariate and multivariate Cox analyses revealed that malignant progression (MP) (P = 0.009) was the only independent predictor for recurrence, while Ki-67 was of minor value in this aspect (P = 0.362). MP-AMs had a significantly higher recurrence rate (P = 0.008), a higher proportion of irregularly shaped tumors (P = 0.013) and significantly lower preoperative Karnofsky Performance Scale (KPS) scores (P = 0.040) than primary (Pri) AMs. No significant difference in Ki-67 expression was detected between these subgroups (P = 0.713).

Conclusions

MP was significantly correlated with an increased incidence of recurrence in GTR-plus-early-EBRT-treated intracranial AMs. Significantly higher frequencies of tumor relapse and irregularly shaped tumors and lower preoperative KPS scores were observed in MP-AMs compared with Pri-AMs. Ki-67 expression is of minor value in predicting tumor recurrence or distinguishing tumor origins in AMs.

Prognostic significance of brain invasion in meningiomas: systematic review and meta-analysis

The WHO 2016 classification introduced brain invasion as a standalone criterion for grade II meningioma (GIIM). We systematically reviewed studies published after 2000 and performed a PRISMA-compliant meta-analysis of the hazard ratios (HRs) for progression-free survival (PFS) between brain-invasive and noninvasive meningiomas. In five studies that included both benign and higher-grade meningiomas, brain invasion was a significant risk factor for recurrence (HR = 2.45, p = 0.0004). However, in 3 studies comparing "brain-invasive meningioma with otherwise benign histology (BIOB)" with grade I meningioma, brain invasion was not a significant predictor of PFS (HR = 1.49, p = 0.23). Among GIIM per the WHO 2000 criteria, brain invasion was a significant predictor of shorter PFS than noninvasive GIIM (HR = 3.40, p = 0.001) but not per the WHO 2016 criteria (HR 1.13, p = 0.54), as the latter includes BIOB. Meta-regression analysis of seven studies of grade II meningioma showed that more frequent BIOB was associated with lower HRs (p < 0.0001). Hence, there is no rationale for brain invasion as a standalone criterion for grade II meningioma, although almost all studies were retrospective and exhibited highly heterogeneous HRs due to differences in brain-tumor interface data availability.

Malignant transformation of WHO grade I meningiomas after surgery or radiosurgery: systematic review and meta-analysis of observational studies

Background

The incidence and clinical features of the malignant transformation of benign meningiomas are poorly understood. This study examined the risk of the malignant transformation of benign meningiomas after surgery or stereotactic radiosurgery.

Methods

We systematically reviewed studies published between 1979 and 2019 using PubMed, Scopus, and other sources. We analyzed pooled data according to the PRISMA guideline to clarify the incidence rate of malignant transformation (IMT) and factors affecting malignant transformation in surgically or radiosurgically treated benign meningiomas.

Results

IMT was 2.98/1000 patient-years (95% confidence interval [CI] = 1.9–4.3) in 13 studies in a single-arm meta-analysis. Although the evidence level of the included studies was low, the heterogeneity of the incidence was mostly explained by the tumor location. In meta-regression analysis, skull base tumors had a significantly lower IMT than non-skull base tumors, but no gender association was observed. IMT after radiosurgery in 9 studies was 0.50/1000 person-years (95% CI = 0.02–1.38). However, a higher proportion of skull base tumors, lower proportion of males, and lower salvage surgery rate were observed in the radiosurgery group than in the surgery group. The median time to malignant change was 5 years (interquartile range = 2.5–8.2), and the median survival after malignant transformation was 4.7 years (95% CI = 3.7–8) in individual case data.

Conclusion

IMT of benign meningioma was significantly affected by the tumor location. Radiosurgery did not appear to increase IMT, but exact comparisons were difficult because of differences in study populations.

Predictive factors for high-grade transformation in benign meningiomas

OBJECTIVE

Although they are generally slow-growing benign tumors, meningiomas may recur after surgery with transformation into atypical meningiomas. The purpose of this study was to investigate the radiological and histopathological factors that predict the risk of tumor progression from a benign to an atypical meningioma.

PATIENTS AND METHODS

All patients treated for recurrent meningiomas in whom the tumor showed histopathologically confirmed high-grade transformation (HGT) from a benign to an atypical meningioma between 2001 and 2017 were included. To evaluate the predictors of transformation, patient medical records documenting the diagnosis of a benign meningioma at the first surgery prior to second surgery with HGT were reviewed. Each patient was matched with four age- and sex-matched controls who were treated for a benign meningioma. The control group comprised all patients without any recurrence for at least 60 months.

RESULTS

Fourteen patients with benign meningioma underwent HGT and were included. The median time interval of transformation was 63 months (range, 19-132 months). Multivariate analysis indicated that an increased mitotic index (odds ratio [OR], 10.409; 95 % confidence interval [CI], 1.297-83.549; P = 0.027) was a significant predictor of transformation. Prominent peritumoral edema (OR, 33.822; 95 % CI, 0.935-223.688; P = 0.054) did not reach the statistical significance.

CONCLUSION

An increased mitotic index may be used as the predictor for HGT of benign meningiomas. Although these tumors with a high risk for transformation do not meet the diagnostic criteria for atypical meningiomas, they may require more attentive observation and management than other benign meningiomas.

Single-Fractionated Stereotactic Radiosurgery for Intracranial Meningioma in Elderly Patients: 25-Year Experience at a Single Institution

BACKGROUND

Stereotactic radiosurgery (SRS) has been accepted as a therapeutic option for intracranial meningiomas; however, the detailed data on outcomes in elderly patients remain unclear.

OBJECTIVE

To delineate the efficacy of SRS for meningiomas in elderly patients.

METHODS

The outcomes of 67 patients aged ≥65 yr who underwent SRS for benign intracranial meningioma (World Health Organization grade I) between 1990 and 2014 at our institution were retrospectively analyzed. The median age was 71 yr (range, 65-83 yr), and the mean and median follow-up were 62 and 52 mo (range, 7-195 mo), respectively. Tumor margins were irradiated with a median dose of 16 Gy, and the median tumor volume was 4.9 cm3 (range, 0.7-22.9 cm3).

RESULTS

Actuarial local tumor control rates at 3, 5, and 10 yr after SRS were 92%, 86%, and 72%, respectively. Previous surgery and parasagittal/falcine location were statistically significant predictive factors for failed tumor control. Mild or moderate adverse events were noted in 9 patients. No severe adverse event was observed. A higher margin dose was significantly associated with adverse events by univariate analysis.

CONCLUSION

SRS is one of the standard therapies for meningiomas in elderly patients, providing both favorable tumor control and a low risk of adverse events under minimum invasiveness.

Extra and Intracranial Meningiomas

Two cases of extracranial meningiomas respectively in the left frontal region in a 64-year-old woman and in the right frontal sinus in a 13-year-old boy are reported. Both cases were associated with an intracranial meningioma later detected after primary histologic diagnosis of the extracranial surgical specimen. The possibility of an extracranial meningioma, expecially when an angioblastic, fibroblastic or meningothelial pattern is prominent, must always be considered together with the existence of an intracranial equivalent, as our 2 cases clearly demonstrate.

Recent Experience in the Management of Meningeal Hemangiopericytomas

Although the histogenesis of meningeal hemangiopericytomas (HMP) remains controversial, both biological and clinical evidence seems to identify these neoplasms as a separate entity with respect to meningiomas. In order to assess the current prognosis of HMP we reviewed our personal experience limited to the last decade (1986-1995): during this period 7 patients (4M, 3F) were treated by surgery alone or surgery combined with postoperative radiotherapy. In spite of meticulous attempts at radical resection, the tumors recurred in all but two cases with a mean interval of 85 months, and a total of 18 operations were performed (2.57/patient; range 1-4). Massive intratumoral hemorrhage determined acute deterioration and required emergency surgery in two cases while in one patient diffuse visceral metastases were discovered at autopsy. Five patients are still alive at follow-up but only 2 of them are in good neurological conditions and without evidence of disease. These results are similar to those reported in other series. In view of our results we conclude that intracranial hemangiopericytomas still have a dismal prognosis. Advances in neuroimaging, neuroanesthesia, microneurosurgery and adjuvant therapy do not seem to have significantly affected the recurrence rate, quality of life and mortality.

Degree of Resection and Ki-67 Labeling Index for Recurring Meningiomas

Objective Meningioma recurrence after resection is likely influenced by multiple surgical and histologic factors. In this study, the degree of resection and tumor immunoreactivity to MIB-1 (i.e., Ki-67 labeling index (LI)) are described in recurrent and non-recurrent meningioma cases. Methods Data regarding tumor location, the degree of resection, histologic features, and the degree of Ki-67 positivity were collected for 32 patients treated between September 2008 and July 2009. Follow-up for recurrence was assessed through five years. Results A total of 32 patients (13 males; 19 females) underwent resection. The mean age was 53.3 years. Gross total resection (GTR) occurred in 25 (78.1%) cases. Near-total resection (NTR) occurred in five (15.6%) cases. Subtotal resection (STR) occurred in two (6.2%) cases. The overall mean Ki-67 LI score was 9.75% (ranging between 1% to 48%). The mean Ki-67 LI for GTR, NTR, and STR cases were 8.0%, 10.2%, and 29.5% respectively. Tumor recurrence occurred in five (15.6%) patients. The mean Ki-67 LI for recurrence lesions was 22.2%. Conclusion We present our descriptive data for Ki-67 LI for initial tumors and recurrence. The risk of recurrence following resection of meningiomas may be associated with the degree of Ki-67 positivity.

Intraspinal meningioma with malignant transformation and distant metastasis

Meningioma is typically considered to be a benign tumor. Malignant transformation and metastasis of meningiomas are rare. Moreover, most meningiomas are intracranial, and there are few reports on intraspinal meningiomas. This report aimed to describe the clinical features and pathological findings of a case of malignant transformation and distant metastasis of intraspinal meningioma, with a review of the literature. A 44-year-old man with a bilateral lower limb paresis was diagnosed with an intradural extramedullary tumor of the thoracic spine. Primary tumor resection was performed, and the histological findings revealed atypical meningioma. The meningioma recurred 2 years after the primary surgery, and a second resection was performed, but only partial resection was possible because of decreased motor evoked potential. At age 48, the patient’s lower limb weakness returned, and a third resection was performed, and the histological finding remained atypical meningioma. At age 54, the tumor increased and stereotactic irradiation was performed. At age 60, the patient was diagnosed with metastatic tumors of the rib, lumbar vertebra, cervical spine, and sacrum. Biopsy of the rib metastatic tumor was performed, and the histological findings revealed anaplastic meningioma. This case is the first report of an intraspinal meningioma that transformed from atypical to anaplastic meningioma with distant hematogenous metastasis.

Histologic and Cytogenetic Patterns in Benign, Atypical, and Malignant Meningiomas

Atypical meningiomas comprise an intermediate category of meningeal neoplasmas with some microscopic features of aggressivity and a capacity for recurrence. We present a clin ical, morphologic, and cytogenetic study of 15 meningiomas. Morphologic and cytogenetic analysis suggested the existence of morphologically typical meningiomas with normal karyotype or monosomy 22 and morphologically atypical meningiomas, with increasing chromosomal abnormalities (complex karyotype) between these two types. Present results suggest the existence of a third type of morphologically typical meningioma that lacks a phenotypical aggressivity but has a complex karyotype. These genotypical characteristics may be related to the aggressivity of these neoplasms. Int J Surg Pathol 2(4):301-310, 1995

Relevance of Simpson grading system and recurrence-free survival after surgery for World Health Organization Grade I meningioma

OBJECTIVE The clinical significance of the Simpson system for grading the extent of meningioma resection and its role as a predictor of the recurrence of World Health Organization (WHO) Grade I meningiomas have been questioned in the past, echoing changes in meningioma surgery over the years. The authors reviewed their experience in resecting WHO Grade I meningiomas and assessed the association between extent of resection, as evaluated using the Simpson classification, and recurrence-free survival (RFS) of patients after meningioma surgery. METHODS Clinical and radiological information for patients with WHO Grade I meningiomas who had undergone resective surgery over the past 20 years was retrospectively reviewed. Simpson and Shinshu grading scales were used to evaluate the extent of resection. Statistical analysis was conducted using Kaplan-Meier curves and Cox proportional-hazards regression. RESULTS Four hundred fifty-eight patients were eligible for analysis. Overall tumor recurrence rates for Simpson resection Grades I, II, III, and IV were 5%, 22%, 31%, and 35%, respectively. After Cox regression analysis, Simpson Grade I (extensive resection) was revealed as a significant predictor of RFS (p = 0.003). Patients undergoing Simpson Grade I and II resections showed significant improvement in RFS compared with patients undergoing Grade III and IV resections (p = 0.005). Extent of resection had a significant effect on recurrence rates for both skull base (p = 0.047) and convexity (p = 0.012) meningiomas. Female sex and a Karnofsky Performance Scale score > 70 were also identified as independent predictors of RFS after resection of WHO Grade I meningioma. CONCLUSIONS In this patient cohort, a significant association was noted between extent of resection and rates of tumor recurrence. In the authors' experience the Simpson grading system maintains its relevance and prognostic value and can serve an important role for patient education. Even though complete tumor resection is the goal, surgery should be tailored to each patient according to the risks and surgical morbidity.

Pathology to enhance precision medicine in oncology: lessons from landscape ecology

A major goal of modern medicine is increasing patient specificity so that the right treatment is administered to the right patient at the right time with the right dose. While current cancer studies have largely focused on identification of genetic or epigenetic properties of tumor cells, emerging evidence has clearly demonstrated substantial genetic heterogeneity between tumors in the same patient and within subclones of a single tumor. Thus, molecular analysis from populations of cells (either a whole tumor or small biopsy of that tumor) is, at best, an incomplete representation of the underlying biology. These observations indicate a significant need to define intratumoral evolutionary dynamics that yield the observed spatial variations in cellular properties. It is generally accepted that genetic heterogeneity among cancer cells is a manifestation of intratumoral evolution, and this is typically viewed as a consequence of random mutations generated by genomic instability within the cancer cells. We suggest that this represents an incomplete view of Darwinian dynamics, which typically are governed by phenotypic variations in response to spatial and temporal heterogeneity in environmental selection forces. We propose that pathologic feature analysis can provide precise information regarding regional variations in environmental selection forces and phenotypic adaptations. These observations can be integrated using quantitative, spatially explicit methods developed in landscape ecology to interrogate heterogenous biological processes in tumors within individual patients. The ability to investigate tumor heterogeneity has been shown to inform physicians regarding critical aspects of cancer progression including invasion, metastasis, drug resistance, and disease relapse.

Third ventricular atypical meningioma which recurred with further malignant progression

Meningiomas in the third ventricle are rare, with only very few cases reported in the literature. We report a case of primary third ventricular anaplastic meningioma in a 49-year-old man who presented with progressive weakness of the left limbs and headache. Magnetic resonance imaging revealed a tumor which seemed to arise from the right thalamus and extending into third ventricle. The tumor was heterogeneously enhanced with gadolinium. It was totally removed by right transventricular-subchoroidal approach. The lesion was intraoperatively found to be whitish hard and embedded in right thalamus, but had attachment to choroid plexus near foramen Monroi with narrow interface. The histological diagnosis was atypical meningioma, WHO Grade II. Lesion recurred 20 months later and was resected via the same approach, which turned out to be papillary meningioma, WHO Grade III. The patient had second recurrence 23 months after second surgery which was operated and the final diagnosis was anaplastic meningioma (WHO Grade III). Literature review showed meningioma of the third ventricle is quite exceptional and more than half of the cases were aggressive subtypes (Grade II or III).

Analysis of progression and recurrence of meningioma using (11)C-methionine PET

OBJECTIVE

The recurrence rate of meningioma after surgery is high, and progression is often observed. The risk factors for recurrence and progression are not clear. We evaluated the risk factors for recurrence and progression in meningioma using (11)C-methionine (MET) positron emission tomography (PET).

METHODS

Thirty-seven patients (mean follow-up, 80 months) with an intracranial meningioma were enrolled. MET PET was performed before treatment between 1995 and 2010, and patients were followed up in an out-patient clinic. Surgery was performed in 33 patients, and a wait-and-see approach was taken in four patients. We evaluated the extent of tumor resection, location, WHO grade, Ki-67 labeling index, and lesion to normal ratio (LN ratio) of MET uptake.

RESULTS

Six of the surgical cases had a recurrence, and two of the observation-only patients had tumor progression. A high LN ratio of MET uptake was a significant risk factor for recurrence and progression with univariate analysis. The area under the curve of receiver operating characteristic curve for the LN ratio of MET uptake was 0.754, and the optimal cutoff value was 3.18 (sensitivity 63 %, specificity 79 %). With multivariate analysis, a high LN ratio of MET uptake, non-gross total resection, and a high WHO grade were significant risk factors for progression and recurrence.

CONCLUSION

A high LN ratio of MET uptake was a risk factor for tumor progression and recurrence. The advantage of MET PET is that it is not invasive and can easily be used to evaluate the whole tumor.

Significance of Simpson grading system in modern meningioma surgery: integration of the grade with MIB-1 labeling index as a key to predict the recurrence of WHO Grade I meningiomas

OBJECT

Techniques for the surgical treatment of meningioma have undergone many improvements since Simpson established the neurosurgical dogma for meningioma surgery in his seminal paper published in 1957. This study aims to assess the clinical significance and limitations of the Simpson grading system in relation to modern surgery for WHO Grade I benign meningiomas and to explore the potential of the cell proliferation index to complement the limitations in predicting their recurrence.

METHODS

The surgical records of patients who underwent resection of intracranial meningiomas at the University of Tokyo Hospital between January 1995 and August 2010 were retrospectively analyzed. The authors investigated the relationships between recurrence-free survival (RFS) and Simpson grade or MIB-1 labeling index value.

RESULTS

A total of 240 patients harboring 248 benign meningiomas were included in this study. Simpson Grade IV resection was associated with a significantly shorter RFS than Simpson Grade I, II, or III resection (p<0.001), while no statistically significant difference was noted in RFS between Simpson Grades I, II, and III. Among meningiomas treated by Simpson Grade II and III resections, however, multivariate analysis revealed that an MIB-1 index of 3% or higher was associated with a significantly shorter time to recurrence.

CONCLUSIONS

The clinical significance of the different management strategies related to Simpson Grade I-III resection may have been diluted in the modern surgical era. The MIB-1 index can differentiate tumors with a high risk of recurrence, which could be beneficial for planning tailored optimal follow-up strategies. The results of this study appear to provide a significant backing for the recent shift in meningioma surgery from attempting aggressive resection to valuing the quality of the patient's life.

The oncofetal protein IMP3: a novel molecular marker to predict aggressive meningioma

CONTEXT

One of the major clinical challenges is to predict recurrence of meningioma. Recently, we have found that IMP3, an oncofetal RNA-binding protein, is a biomarker to predict aggressive tumors.

OBJECTIVE

To investigate whether IMP3 can be used as a new biomarker to predict the recurrence and overall survival of patients with meningiomas.

DESIGN

One hundred seven patients with primary meningiomas were investigated for expression of IMP3 by immunohistochemistry and whether expression of this molecule correlated with tumor recurrence and overall survival.

RESULTS

Tumor recurrence was found in 13 of 107 patients with primary meningioma. Seven of 107 patients (6.5%) with primary meningiomas expressed IMP3. Kaplan-Meier plots and log-rank tests showed that patients with IMP3-positive tumors had a much higher recurrence rate (P = .004) and a poorer overall survival (P < .001) than did patients with IMP3-negative tumors. The 5-year recurrence-free and overall survival rates were 0% and 36% in IMP3-positive patients versus 89% and 94% in IMP3-negative patients, respectively. Multivariable analysis of IMP3 status (positive versus negative) in primary tumors showed a hazard ratio of 17.89 for recurrence (P = .01), which was much higher than hazard ratios associated with all other known risk factors including higher tumor grades and Ki-67 labeling index.

CONCLUSIONS

IMP3 is a potential independent prognostic biomarker that can be used at the time of initial diagnosis of meningioma to identify patients who have a high risk of developing a recurrence.

Acute recurrent haemorrhage of an intracranial meningioma

Meningioma-associated haemorrhages are rare. To our knowledge this is the first report of a patient with an acute two-stage haemorrhage of a benign intracranial meningioma (World Health Organization grade I) verified by cranial CT scan and histopathological examination. Early surgery with complete tumour removal led to a good outcome for the patient.

Hemangiopericytoma in the lateral ventricle

A 31-year-old female presented with a particularly rare hemangiopericytoma (HPC) in the right lateral ventricle manifesting as a 6-month history of visual disturbance and headache. Left hemianopsia and choked disc were identified by an ophthalmologist who referred her to us. Magnetic resonance imaging demonstrated a 5-cm homogeneously enhanced mass in the trigone of the right lateral ventricle. The tumor was totally removed by two stage surgery. The histological findings were consistent with HPC. HPC is very important to differentiate from meningioma and solitary fibrous tumors because HPC is more aggressive. The histological and immunochemical findings are important for the differential diagnosis. The present case showed no local recurrence or metastasis without radiation therapy for 4 years, indicating that radiation therapy is not absolutely imperative for patients with intraventricular HPC showing low MIB-1 staining index after total removal.

Spheno-orbital meningiomas: outcome after microsurgical treatment: a clinical review of 30 cases

OBJECTIVE

Spheno-orbital meningiomas represent a delicate subtype of intracranial meningiomas involving the sphenoid wing, orbit and important neurovascular structures such as cavernous sinus, carotid artery or optic nerve. Insidious and aggressive dural, bone and orbital involvement contains several defiances to adequate resection, which provides high rates of recurrence.

METHODS

This retrospective case analysis consisted of 30 patients, who were surgically treated for spheno-orbital meningiomas performing a fronto-pterional approach by or under the supervision of the senior author (J. Meixensberger) between May 2001 and February 2006. There were 22 woman and eight men with a mean age of 54.4 years. The follow-up period ranged from 3 to 75 months (mean: 33.7 months).

RESULTS

The majority of patients presented with a clinical triad of visual impairment (74%), progressive proptosis (55%) and visual field defects (40%). Total microscopic tumor resection was achieved in ten patients (33%). Visual acuity improved in 65% of the patients, and 40% of these returned to normal vision. Pre-existing cranial nerve deficits remained unchanged in the majority of patients (88%) and improved in 12%. Temporary new cranial nerve deficits occurred in three patients. The rate of permanent non-visual morbidity was 10% (three of 30 patients). Eight patients (27%) received post-operative radiotherapy with an overall tumor growth control rate of 63%. The overall recurrence rate was 27% (eight of 30 patients).

CONCLUSION

Sufficient tumor control can be achieved with minimal morbidity and satisfying functional results.

MIB1 proliferation index in meningiomas: does it predict recurrence? A clinicopathological study

The usefulness of proliferation marker MIB1 in predicting recurrences in cranial meningiomas when other clinical and pathological factors are considered was assessed. Data from 65 patients with meningiomas were analysed and their clinical notes reviewed to define the Simpson grade of surgical excision, the location of tumour, amongst other clinical factors. The diagnosis was reviewed; immunohistochemical staining for a proliferation marker MIB1 was carried out on archival formalin-fixed, paraffin-embedded tumour and a labelling index for MIB1 (MIB1 L1) calculated. Analysis was undertaken of the impact of histology, grade of excision, tumour location and proliferation index on the risk of recurrence. The grade of surgical resection and histology type were the most important factors likely to predict recurrence. MIB1 LI was not considered useful in predicting tumour recurrence.

The use of stereotactic radiosurgery in the management of meningiomas

This is a systematic review of a consecutive series of 309 meningiomas treated with gamma knife stereotactic radiosurgery between 1994 and 2000. There was an extreme selection bias towards lesions unfavourable for surgery, determined by the patients referred for treatment: 70% of tumours involved the skull base, 47% specifically the cavernous sinus: 15% of patients had multiple meningiomatosis or type 2 neurofibromatosis. Tumour histology was the main determinant of growth control (p < 0.001), the 5-year actuarial control rates being 87% for typical meningiomas, 49% for atypical tumours and 0% for malignant lesions. Complications from radiosurgery were rare, occurring in 3% of tumours, and were most frequently trigeminal and eye movement disturbances treating cavernous sinus meningiomas. Given the problems inherent in managing these tumours, radiosurgery is a valuable strategy and adjuvant treatment for these meningiomas.

Extraneural metastases from cranial meningioma: a case report

Extracranial metastases from brain meningiomas is a rare, but well-documented entity. Metastases occur mostly in the lungs, pleura and liver, but may also affect lymph nodes and bones. We report here on a patient who was treated for an atypical brain meningioma with multiple surgeries and multiple sessions of stereotactic radiosurgery with good control of his brain disease. Thirteen years after diagnosis, he developed bilateral large sacroiliac and abdominal metastases.

Combined proton and photon conformal radiotherapy for intracranial atypical and malignant meningioma

PURPOSE

To evaluate retrospectively the efficacy of conformal fractionated radiotherapy combining proton and photon beams after primary surgery for treatment of atypical and malignant meningiomas.

PATIENTS AND METHODS

Between September 1999 and October 2006, 24 patients (12 male, 12 female) with histopathologically proven meningioma (atypical 19, malignant 5) received postoperative combined radiotherapy with a 201-MeV proton beam at the Centre Protontherapie d'Orsay and a high-energy photon beam. Six patients underwent gross total resection and 18 a subtotal resection. Median gross tumor volume and clinical target volume were 44.7 cm(3) and 153.3 cm(3), respectively. Mean total irradiation dose was 65.01 CGE (cobalt gray equivalent), with a mean proton total dose of 34.05 CGE and a mean photon total dose 30.96 CGE.

RESULTS

The median (range) follow-up interval was 32.2 (1-72) months. The overall mean local relapse-free interval was 27.2 (10-50) months, 28.3 (10-50) months for atypical meningioma and 23 (13-33) months for malignant meningioma. Ten tumors recurred locally. One-, 2-, 3-, 4-, 5-, and 8- year local control rates for the entire group of patients were 82.9% +/- 7.8%, 82.9% +/- 7.8%, 61.3% +/- 11%, 61.3% +/- 11%, 46.7% +/- 12.3%, and 46.7% +/- 12.3%, respectively. One-, 2-, 3-, 4-, 5-, and 8- year overall survival rates were 100%, 95.5% +/- 4.4%, 80.4% +/- 8.8%, 65.3% +/- 10.6%, 53.2% +/- 11.6%, and 42.6% +/- 13%, respectively. Survival was significantly associated with total dose. There was no acute morbidity of radiotherapy. One patient developed radiation necrosis 16 months after treatment.

CONCLUSIONS

Postoperative combination of conformal radiotherapy with protons and photons for atypical and malignant meningiomas is a well-tolerated treatment producing long-term tumor stabilization.

Adjuvant stereotactic radiosurgery after resection of intracranial hemangiopericytomas

PURPOSE

To evaluate adjuvant stereotactic radiosurgery (SRS) in the management of recurrent or residual intracranial hemangiopericytomas (HPCs), we assessed tumor control, survival, and complications in patients who had undergone gamma knife SRS as part of multimodal therapy.

METHODS AND MATERIALS

We retrospectively reviewed the records of consecutive 20 HPC patients who had undergone SRS for 29 tumors. The median patient age was 51.5 years (range, 8.9-80.2). All patients had undergone previous surgical resection of their tumors. In addition, 12 patients underwent fractionated radiotherapy before SRS. Of the 20 patients, 16 patients had low-grade HPCs (20 tumors) and 4 had high-grade anaplastic HPCs (9 tumors). The median radiosurgery target volume was 4.5 cm(3) (range, 0.07-34.3), and the median marginal dose was 15.0 Gy (range, 10-20).

RESULTS

At an average of 48.2 months (range, 7.2-124.1), 5 patients had died of metastases and 3 patients had died of disease progression. The overall survival after radiosurgery was 100%, 85.9%, and 13.8% at 1, 5, and 10 years, respectively. The follow-up imaging studies demonstrated tumor control in 21 (72.4%) of 29 tumors. The progression-free survival rate after SRS at 1, 3, and 5 years was 89.1% for low-grade HPCs and 88.9%, 66.7%, and 0%, respectively, for high-grade HPCs. The factors associated with improved progression-free survival included lower grade and higher marginal dose. Eight patients had intracranial or extracranial metastasis after the initial diagnosis, which correlated with the shorter survival.

CONCLUSION

The results of our study have shown that adjuvant SRS after tumor resection is an important management option for patients with residual or recurrent HPCs and is particularly effective for less-aggressive tumors.

Acute haemorrhagic presentation of an intracranial meningioma

Acute haemorrhagic presentation of a meningioma is an extremely rare event. In a review of the literature, 44 such cases were found and only eight of them presented with sudden onset of coma. The outcome in these eight cases was, with few exceptions, poor. We report the case of a 72-year-old woman who presented with sudden onset of coma due to a massive haemorrhage into a frontal meningioma. The diagnosis was suspected on the basis of a non-enhanced computed tomographic (CT) scan and considering the clinical status of the patient, emergency evacuation of the haematoma and complete macroscopic resection of the tumour was performed without further diagnostic procedures. The patient fully recovered. Clinical examination and contrast enhanced CT scan at 3 months follow-up were considered normal. The prognosis for haemorrhagic presenting meningiomas is poor especially for those presenting with acute onset of coma. The outcome seems to be improved with rapid decompression and tumour removal. We would like to stress the need to keep the diagnostic procedures to a minimum once a haemorrhagic decompensating meningioma is suspected despite the risks associated with an incomplete radiological work up before surgery. Complete or at least gross tumour removal at the time of emergency surgery seems to be associated with a better outcome and should be attempted in all patients, even those presenting with acute signs of herniation.

De novo versus transformed atypical and anaplastic meningiomas: comparisons of clinical course, cytogenetics, cytokinetics, and outcome

OBJECTIVE

The clinical course of atypical and anaplastic meningiomas is heterogeneous. As malignant gliomas, aggressive meningiomas may arise de novo or transform from a benign tumor. This study aims to compare differences in clinical behavior, cytogenetics, cytokinetics, receptor status, and outcome between de novo malignant meningiomas and meningiomas that progressed to malignancy.

METHODS

Data from 36 patients with atypical or anaplastic meningiomas were selected for retrospective analysis and divided into two subgroups: 1) de novo atypical or anaplastic tumors and 2) tumors that progressed from a lower grade. We analyzed data concerning patients' sex, age, tumor location, number of operations, status of hormone receptors, proliferative indices, cytogenetic findings, additional therapy, and survival. For meningiomas with progression, we calculated the interval between initial diagnosis and tumor progression.

RESULTS

For atypical meningiomas, the subgroups had significant differences in status of progesterone receptors, proliferative indices, cytogenetics, and patients' outcome. The anaplastic group had similar differences, but they did not reach statistical significance because of the small numbers. There was a loss of part or monosomy of chromosome 10 and an increased monosomy or derivative chromosome 1 combined with monosomy of chromosome 14. These phenomena occurred mainly in patients with malignant transformation who had a worse outcome.

CONCLUSION

De novo malignant meningiomas and meningiomas with malignant transformation may represent distinct subgroups of atypical and anaplastic meningiomas.

Application of oncogenetic trees mixtures as a biostatistical model of the clonal cytogenetic evolution of meningiomas

Meningiomas are mostly benign tumors that originate from the coverings of brain and spinal cord. Typically, they reveal a normal karyotype or monosomy for chromosome 22. Rare clinical progression of meningiomas is associated with a nonrandom pattern of secondary losses of other autosomes. Deletion of the short arm of one chromosome 1 appears to be a decisive step for anaplastic growth in meningiomas. We calculated an oncogenetic tree model that estimates the most likely cytogenetic pathways of 661 meningioma patients in terms of accumulation of somatic chromosome changes in tumor cells. The genetic progression score (GPS) estimates the genetic status of a tumor as progression in the corresponding tumor cells along this model. Large GPS values are highly correlated with early recurrence of meningiomas [p < 10(-4)]. This correlation holds even if patients are stratified by WHO grade. We show that tumor location also has an impact on genetic progression. Clinical relevance of the GPS is thus demonstrated with respect to origin, WHO grade and recurrence of the tumor. As a quantitative measure the GPS allows a more precise assessment of the prognosis of meningiomas than categorical cytogenetic markers based on single chromosomal aberrations.

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.

Stereotactic radiation treatment for recurrent nonbenign meningiomas

Object

The authors analyzed the results of stereotactic radiosurgery (SRS) and stereotactic radiotherapy (SRT) for the treatment of recurrent meningiomas that were described at initial resection as showing aggressive, atypical, or malignant features (nonbenign).

Methods

Twenty-five patients who underwent SRS and/or SRT for nonbenign meningiomas between December 1992 and August 2004 were included. Thirteen of these patients underwent treatment for multiple primary or recurrent lesions. In all, 52 tumors were treated. All histological sections were reviewed and reclassified according to World Health Organization (WHO) 2000 guidelines as benign (Grade I), atypical (Grade II), or anaplastic (Grade III) meningiomas. The median follow-up period was 42 months.

Seventeen (68%) of the cases were reclassified as follows: WHO Grade I (five cases), Grade II (11 cases), and Grade III (one case). Malignant progression occurred in eight cases (32%) during the follow-up period; these cases were considered as a separate group. The 3-year progression-free survival (PFS) rates for the Grades I, II, and III, and malignant progression groups were 100, 83, 0, and 11%, respectively (p < 0.001). In the Grade II group, the 3-year PFS rates for patients treated with SRS and SRT were 100 and 33%, respectively (p = 0.1). After initial treatment, 22 new tumors required treatment using SRS or SRT; 17 (77%) of them occurred inside the original resection cavity. Symptomatic edema developed in one patient (4%).

Conclusions

Stereotactic radiation treatment provided effective local control of “aggressive” Grade I and Grade II meningiomas, whereas Grade III lesions were associated with poor outcome. The outcome of cases in the malignant progression group was intermediate between that of the Grade II and Grade III groups, with the lesions showing a tendency toward malignancy.

Meningothelioma as the predominant histological subtype of midline skull base and spinal meningioma

Object

This study was undertaken to test a hypothesis that meningiomas of the midline skull base and spine are predominantly of the meningothelial histological subtype.

Methods

The cases of 794 consecutive patients who underwent resection for meningioma at the Cleveland Clinic between January 1991 and March 2004 were reviewed retrospectively. The authors analyzed the relationship between the tumors’ histological subtypes and sites of origin in the 731 patients from this group who harbored tumors that were determined to be benign histologically (World Health Organization Grade I).

Meningothelial meningiomas (MMs) accounted for 63.5% (464/731) of the Grade I tumors. The incidence of MM according to the site of origin was as follows: 84.9% (186/219) in the midline skull base, 58.3% (35/60) in the lateral skull base, 48.5% (183/377) in a non–skull base location, and 80% (60/75) in spinal locations. The incidence of MM in the midline skull base and spinal locations were significantly higher than in non–skull base or lateral skull base locations.

Conclusions

Meningiomas of the midline neuraxis are predominantly meningotheliomas. Analysis of the increasingly available data on genetic and topographic characteristics of MMs suggests that they may represent a unique entity, contrary to the prevailing belief that all benign meningiomas are identical tumors.

Proliferation potential of spinal meningiomas

OBJECTIVES

The goal of the present study was to quantitatively assess the proliferation index and progesterone receptor status of spinal versus intracranial meningiomas and to determine if these biological indicators can describe the clinical behavior of these tumors. This information could provide the spinal surgeon with important additional information concerning surgical management and follow-up recommendations for the individual patient.

METHODS

The study group consisted of 26 patients with spinal and 241 patients with intracranial meningiomas. Patients with atypical or anaplastic tumors as well as with neurofibromatosis type II were excluded from the study. Furthermore both groups were matched according to age, sex and resection grade (total resection according the Simpson classification). Proliferation index (Ki-67 Labelling index [LI]) and progesterone-receptor (PR) status of spinal and intracranial meningiomas were compared. Clinical charts including surgical and histological records and imaging studies were reviewed. Correlations with histological subtype, intratumoral calcifications, tumor vascularity and recurrence-free survival were analyzed.

RESULTS

Compared to the spinal group with a mean Ki-67 LI of 2.48% and a positive PR-status of 46%, proliferation rates of intracranial meningiomas were significant higher (Ki-67 LI 3.6%; P-value 0.041). No significant difference in PR status was seen (spinal PR-status 46%, P-value 0.261). Furthermore spinal meningiomas were less vascularized and showed less intratumoral calcifications. Time to recurrence was similar in spinal and intracranial tumors.

CONCLUSION

Spinal and intracranial meningiomas differ in their proliferation activity but not in their PR status. However, despite lower proliferation rates, time to recurrence in spinal and cranial meningiomas is comparable in totally excised tumors. Further studies are needed to determine the role of other biological indicators in spinal meningioma growth and response to therapy.

Spontaneous intracranial meningioma bleeding: clinicopathological features and outcome

OBJECT

The aim of this study was to determine the clinicopathological features of patients with intracranial bleeding from unsuspected meningioma and to relate these data to surgery-related outcome.

METHODS

The authors report on two cases in which hemorrhage of an unsuspected meningioma occurred in the tentorial ridge and in the falx, and they discuss the details of 143 cases described in the literature. A bleeding propensity index of the meningioma, related to the patient's age, sex, and the lesion's intracranial location and histological type was computed as a ratio between the frequencies of bleeding meningioma and all meningiomas. This was tested by independent samples t-test for proportions. A chi-square test was used to determine the correlations between several variables: location and type of bleeding; survival and type of bleeding; and consciousness and survival. Increased bleeding tendency was found to be associated with two age groups (< 30 years and > 70 years), convexity and intraventricular locations, and fibrous meningiomas. The overall mortality rate documented in cases of bleeding meningiomas was 21.1% (13.9% in the computerized tomography [CT] scanning era), and that in surgically treated cases was 9.5% (7.5% in the CT scanning era). The overall major morbidity rate was 36% (33.8% in the CT scanning era). Overall 96.2% of conscious patients survived after their meningiomas spontaneously hemorrhaged. In patients who were unconscious before surgery, overall mortality rate was 74.1%, and that in surgically treated cases was 46.2%.

CONCLUSIONS

The mortality rate in preoperatively conscious patients (those in whom acute deterioration and irreversible brain damage were prevented by early diagnosis and definitive surgery) was similar (< 3% in the CT scanning era) to that documented in cases in which meningiomas did not bleed. In contrast, the associated morbidity rates were much higher. One-stage total removal of the hemorrhagic meningioma and hematoma is the treatment of choice in such patients.

Solitary fibrous tumor of the spinal cord: A clinicopathologic study of two cases

Two cases of solitary fibrous tumor of the spinal cord are described. The patients were two men, 36 and 47 years old. Clinically, they sought medical care because of progressive paresthesias or urinary incontinence caused by a nodular, fairly circumscribed intraspinal tumor of the cervical and thoracic spinal cord, respectively. Preoperative magnetic resonance images suggested meningioma. In both cases, laminectomy with tumor resection was carried out. Microscopically, the tumors featured short spindle cells haphazardly enmeshed in a collagenized ground substance. No atypia, necrosis, or significant mitotic activity was recognized. Tumor cells were positive for CD34, bcl2, vimentin, and, in one case, CD99. Both patients recovered from symptoms and are alive and well 12 and 18 months, respectively, after surgical resection. The differential diagnosis includes meningioma, schwannoma, and hemangiopericytoma, all of which may occur in the spinal canal. A careful morphologic approach and the judicious use of immunohistochemistry may assist in distinguishing among these conditions, although some irreducible difficulties may be posed by hemangiopericytoma. Although solitary fibrous tumor of the spinal cord presents with fairly comparable clinical, instrumental, and pathologic patterns, we believe that compilation of more cases is needed to segregate it as a distinct clinicopathologic entity.

Expression of cytokeratin by malignant meningiomas: diagnostic pitfall of cytokeratin to separate malignant meningiomas from metastatic carcinoma

Based on clinical and histologic features, differentiating metastatic carcinomas from benign or malignant meningiomas usually is not difficult. Occasionally, however, in some patients without a clinical history of carcinoma, malignant meningiomas can morphologically simulate metastatic carcinoma, necessitating an immunohistochemical study for cytokeratin to make a correct diagnosis. However, the utility of immunohistochemical markers to separate malignant meningioma from metastatic carcinoma has not been investigated. The immunoperoxidase method with antigen retrieval was used to characterize the expression of three cytokeratins (AE1/AE3, CAM 5.2, and Pan cytokeratin), EMA, CEA, Ber-EP4, CD 15, and B72.3 in 12 previously diagnosed malignant meningiomas, 20 benign meningiomas, and 20 metastatic carcinomas. Cytokeratin expression was detected in 75% of malignant meningiomas, 0% of benign meningiomas, and 100% of metastatic carcinomas. While epithelial markers of Ber-EP4, CEA, B72.3 and CD-15 were positive in 90, 80, 70 and 65% of the metastatic carcinoma, respectively, they were negative in all 12 malignant meningioma examined. Vimentin immunoreactivity was seen in all benign and malignant meningiomas, and in 20% of metastatic carcinomas. Our results indicated that cytokeratin is not a reliable immunohistochemical marker to separate a malignant meningioma from metastatic carcinoma. A panel of epithelial markers including Ber-EP4, CEA, B72.3 and CD-15, and vimentin may be needed to separate malignant meningioma from metastatic carcinoma. Cytokeratin expression can be a potential pitfall for confusing a malignant meningioma with a metastatic carcinoma.

Malignant progression in meningioma: documentation of a series and analysis of cytogenetic findings

Object. The malignant progression of benign tumors is well documented in gliomas and other systemic lesions. It is also well known that some meningiomas become progressively aggressive despite their original benign status. The theory of clonal evolution is widely believed to explain malignant progression in meningioma; however, the data used to explain stepwise progression have typically been derived from the cytogenetic analysis of different types of tumors of different grades and in different patients. In this study, the authors examined the data obtained in a group of patients with meningiomas that showed clear histopathological progression toward a higher grade of malignancy and then analyzed the underlying cytogenetic findings.

Methods. Among 175 patients with recurrent meningiomas, 11 tumors showed a histopathological progression toward a higher grade that was associated with an aggressive clinical course. Six tumors progressed to malignancy and five to the atypical category over a period averaging 112 months. Tests for MIB-1 and p53 and cytogenetic studies with the fluorescence in situ hybridization (FISH) method were performed in successive specimens obtained in four patients.

The MIB-1 value increased in subsequent samples of tumors. Cytogenetic analysis with FISH showed deletions of 22, 1p, and 14q. In all but one case, these aberrations were also present in the previous specimen despite its lower hispathological grade.

Conclusions. The authors documented the progression of meningiomas from benign to a higher histological grade. These tumors were associated with a complex karyotype that was present ab initio in a histologically lower-grade tumor, contradicting the stepwise clonal evolution model. Although it was limited to the tested probes, the FISH method appears to be more accurate than the standard cytogenetic one in detecting these alterations. Tumors that present with complex genetic alterations, even those with a benign histological grade, are potentially aggressive and require closer follow up.

Angiomatous Meningioma

To characterize histopathological and clinical features of angiomatous meningioma, 38 cases of angiomatous meningioma, ie, meningiomas whose vascular component exceeded 50% of the total tumor area, are reported. In addition to histologic examinations, clinical characteristics as well as follow-up data were compiled. Angiomatous meningiomas constituted 2.1% of all meningiomas. Histologic signs of atypia or anaplasia were not observed in any tumor. The mean MIB-1/Ki67 proliferation index was 2.4%. Based on vessel size, two distinct histologic subtypes were identified, which differed in localization but not with regards to sex, age, presence of peritumoral edema, MIB-1/Ki67 proliferation index, or progesterone receptor status. In patients with gross tumor resection, no recurrences occurred. To conclude, angiomatous meningiomas share histologic and clinical features of benign meningiomas. Since all angiomatous meningiomas examined here were grade 1 tumors, the diagnosis of angiomatous meningioma may have prognostic implications. Therefore, the existence of this rare subgroup of meningioma appears justified.

The combination of mitotic and Ki-67 indices as a useful method for predicting short-term recurrence of meningiomas

BACKGROUND

The most relevant factor in the progression-free survival (PFS) of patients with meningiomas is the malignant grade. However, using only the current World Health Organization (WHO) definition that does not consider precise quantitative indicators, an unequivocal diagnosis of the malignant grade is difficult. In our retrospective study of the PFS of meningioma patients, we focused on mitoses and the Ki-67 staining index of tumor specimens obtained at the initial surgery.

METHODS AND RESULTS

A total of 349 patients with intracranial meningioma, operated between 1978 and 2000, were followed for a mean of 7 years. According to the mitotic index (MI), we classified them into 3 groups. In Group A (n = 326), slide-mounted tumor samples exhibited no mitoses; in Group B (n = 15) there were fewer than 4 mitoses, and in Group C (n = 8) 4 or more mitoses were seen per 10 high-power fields (HPF). The estimated 5-year PFS rates in Groups A, B, and C were 93%, 10%, and 13% respectively. The mean PFS for Group A was 148 months; in Groups B and C the median PFS was 43 and 16 months, respectively. A Ki-67 staining index (SI) of less than 1% corresponded with no mitosis, while an SI exceeding 5% was indicative of the presence of mitoses.

CONCLUSION

In meningioma patients, no mitoses and/or a Ki-67 SI <1% signals a favorable outcome. An SI >5% or the presence of mitoses, even fewer than 4 in 10 HPF, is suggestive of a short PFS irrespective of other pathologic features. We suggest that in combination, assay of the Ki-67 SI and the MI represents a reliable, quantitative tool for predicting PFS in meningioma patients.

Medulloblastoma in a cat: clinical and MRI findings

A two-year-old, castrated crossbred cat presented with loss of balance and anorexia. A mass of the caudal aspect of the cerebellum was revealed by magnetic resonance imaging (MRI). The mass was hypointense on T1-weighted images, iso- and hyperintense on T2-weighted images and was enhanced by intravenous gadolinium contrast medium. The MRI characteristics of this case were similar to those of medulloblastoma of the cerebellar vermis in humans. The authors were able to remove almost all of the tumour. The cat was discharged from hospital on day 22 after surgery, but died on day 45. The excised tissue was histologically diagnosed as medulloblastoma.