DNA in meningioma tissues and explant cell cultures. A flow cytometric study with clinicopathological correlates

New classification scheme for the prognostic stratification of meningioma on the basis of chromosome 14 abnormalities, patient age, and tumor histopathology

PURPOSE

Meningiomas are usually considered benign tumors. However, relapses occur in 10% to 20% of all patients, including both histopathologically aggressive and benign tumors. This study explored the value of numerical abnormalities for 10 different chromosomes in meningiomas for predicting relapse-free survival (RFS).

PATIENTS AND METHODS

This study prospectively analyzed the frequency of numerical abnormalities of chromosomes 1, 9, 10, 11, 14, 15, 17, 22, X, and Y in 70 meningioma patients by fluorescence in situ hybridization and their relationship with disease characteristics at diagnosis and patients' outcome.

RESULTS

Results showed the presence of numerical abnormalities for one or more chromosomes in most patients (77%). Chromosome 22 in the whole series and chromosome Y in males were those more frequently altered, followed by chromosomes 1, 14, and X in females. Patients with abnormalities of chromosomes 1, 9, 10, 11, 14, 15, 17, the sex chromosomes, and gains of chromosome 22 were associated with adverse prognostic features, more frequent relapses, and shorter RFS. Multivariate analysis showed that tumor grade together with chromosome 14 status and age were the best combination of independent variables for predicting RFS. According to these variables, all patients with a score of two or more than two adverse prognostic factors had experienced relapse at 5 years, whereas none of those with a score of zero had experienced relapse 10 years after surgery.

CONCLUSION

In addition to age and histologic grade, abnormalities of chromosome 14 contribute to a better prognostic stratification of meningioma patients at diagnosis. Additional prospective studies in larger series of patients, also including larger numbers of patients who experienced relapse, are necessary to confirm the utility of the proposed predictive model.

Proliferation rate of intracranial meningiomas as defined by the monoclonal antibody MIB-1: correlation with peritumoural oedema and other clinicoradiological and histological characteristics

Paraffin-embedded surgical specimens from 55 meningiomas were immunostained after microwave processing using the streptavidin/peroxidase method and the monoclonal antibody (moAb) MIB-1 to the Ki-67 antigen. The authors assessed proliferative labelling index (LI) from a series of surgically removed meningiomas using immunohistochemical methods and MIB-1, and they correlated this index with clinical, radiological, and histological factors. No relationship was found between LI, sex, age, resection and histological grades, or volume. Symptoms, location, and peritumoural oedema did have a significant relationship to the MIB-1 LI. The symptomatic patients, i.e. those with tumours at the base of the skull and with GR3 peritumoural oedema (grade 3), had a greater chance of higher MIB-1 LI. It was proven that the increase of one unit in peritumoural oedema classification gave an increased risk of 3.312 and an LI greater than 3%. The authors also discuss the different methods of evaluating LIs in meningiomas, based on the available literature.

Prognostic significance of cyclin a expression in meningiomas

Unconstrained cell proliferation is characteristic of tumors. It is caused by the functional disorders of proteins that constitute the cell cycle mechanism. The cell cycle is controlled by cyclins, cyclin-dependent kinases, and cyclin-dependent kinase inhibitors. Many reports have proved, in cancers, that cyclins, cyclin-dependent kinases, and cyclin-dependent kinase inhibitors are out of control. Cyclin A is a protein that regulates critical transition of the cell cycle. The expression of cyclin A in meningiomas by immunohistochemical method was investigated. Furthermore, the correlation among cyclin A expression, clinical course, and proliferative potential were also evaluated. Seventy-seven meningiomas were studied. The mean cyclin A labeling indices were as follows: benign meningiomas, 1.01% +/- 0.62%; atypical meningiomas, 4.23% +/- 1.82%; and anaplastic meningiomas, 7.72% +/- 0.88%. Analyses of variance showed that significant differences existed between tumor grades for cyclin A labeling indices. A linear positive correlation between the cyclin A labeling index and bromodeoxyuridine labeling index was observed. The multivariate analysis using Cox's hazards model showed a high cyclin A labeling index (>3%) was a significant risk factor for recurrence. A high Ki-67 labeling index (>5%) and high tumor grade (World Health Organization grade II, III) were also significant risk factors for recurrence. These results suggested that the evaluation of cyclin A expression in meningiomas provides significant clinical information, especially as an independent prognostic indicator.

Gains of chromosome 22 by fluorescence in situ hybridization in the context of an hyperdiploid karyotype are associated with aggressive clinical features in meningioma patients

BACKGROUND

Meningiomas usually are considered to be benign tumors; however, 10-20% of cases recur. Few disease characteristics have proved to have prognostic impact for predicting disease free survival. The objective of the current study was to explore the prognostic value of numeric abnormalities of chromosome 22 for meningioma patients.

METHODS

In this study, the authors prospectively analyzed the incidence of numeric chromosome abnormalities of chromosome 22 by interphase fluorescence in situ hybridization, using a specific probe for the bcr gene located in chromosome 22q11.2, on a total of 88 consecutive meningioma patients. The authors also analyzed its correlation with both the clinicobiologic characteristics at presentation and the patient's outcome.

RESULTS

The authors' results show that monosomy 22 was present in 49% of the cases and that this numeric chromosomal abnormality is not associated with other prognostic features of the disease. In contrast, gains (trisomy/tetrasomy) of chromosome 22 were detected in 8 (9%) cases who simultaneously showed gains for other chromosomes and represent an adverse prognostic factor regarding disease free survival (P = 0.001); in addition, trisomy/tetrasomy 22 was more frequently related to younger patients (P = 0.001), aggressive histopathologic features (P < 0.000), a greater incidence of DNA aneuploidy (P =0.006), and a higher proportion of S-phase tumor cells (P = 0.02).

CONCLUSIONS

In summary, the authors conclude that loss of a copy of chromosome 22 is a frequent finding in meningioma tumors, but it does not affect the clinical outcome of these patients. In contrast, gains (trisomy/tetrasomy) of chromosome 22, in the context of an hyperdiploid karyotype, although much less frequent, are associated with a more aggressive disease course.

Expression of the proliferating cell nuclear antigen and clinicopathological features in intracranial meningiomas

PC10, a monoclonal antibody (mAb) to proliferating cell nuclear antigen (PCNA) is known to show immunoreactivity in paraffin-embedded specimens. The authors present the relation between PCNA expression and clinicopathological features in 38 intracranial meningiomas. PCNA scores were obtained by immunohistochemical staining of the paraffin-embedded sections using a streptavidin-biotin immunoperoxidase method with PC10 mAb. Univariate analysis showed that high PC10 scores were associated with old age (> or = 50 years old), male, recurrent tumours, and meningothelial type. However, these high scores did not reach a statistical significance (P> 0.05). PC10 scores of the basal meningioma tended to be higher than that of the hemispheric meningioma (P< 0.05). The staining intensity of PCNA was also markedly increased in basal meningiomas. It is suggested that the proliferative potential is higher in basal meningiomas than in hemispheric meningiomas. Moreover, these results could reflect high recurrence and difficulty in management of the skull base meningiomas.

Biologic parameters that correlate with the prognosis of human gliomas

Much clinical and biologic data have been processed in the search for useful objective parameters to predict brain tumor behavior. Seventy cases of astrocytic glioma collected by a single clinical team were studied using a full complement of clinical procedures: follow up (7 years), histologic analysis, DNA content estimation, and cell kinetics by flow cytometry. Proliferating cell nuclear antigen (PCNA) was determined by immunocytochemical-coupling flow cytometry (PFC) and also by counting under light microscopy (PIHC). A statistical evaluation was carried out to establish the usefulness of several parameters for glioma prognosis. The cases were histologically classified as 14 low-grade astrocytomas, 20 anaplastic astrocytomas, and 36 glioblastomas multiforme. The survival curve showed significant differences between histologic groups. Diploid populations were more frequent in low-grade astrocytomas, and aneuploid tumors often had increased S-phase and proliferative fractions. The PCNA-labeled index (PCNA-LI) increased with malignancy and correlated with histologic grading (P = 0.01). The PCNA-LI and age segregated low- from high-grade astrocytomas (including anaplastic astrocytoma and glioblastoma multiforme), but none of the variables considered differentiated anaplastic astrocytoma from glioblastoma multiforme. The Cox regression test displayed significant values for age, histologic diagnosis, and PCNA determinations when considered in tandem. Discriminant analysis obtained a function integrating age and specifically PIHC-LI to help in the prognosis of doubtful cases. The results emphasize the importance of parameters integrating different variables in an attempt to provide an accurate prognosis, the most significant being age, histopathologic diagnosis, and the proliferative fraction determined by PCNA.

Long-term follow up of progesterone receptor status in benign meningioma: a prognostic indicator of recurrence?

OBJECT

A long-term prospective analysis of patients with benign meningioma was undertaken to determine whether progesterone receptor (PR) status of the excised tumor has any influence on recurrence.

METHODS

Between 1983 and 1985, a total of 62 meningiomas in 53 patients (age range 19-79 years, mean age 55.6 years) were studied for clinical, histological, and pathological characteristics, including hormone receptor status and DNA features. Progesterone receptor status was quantified by cryostat section assay, and then factors affecting recurrence were analyzed. During 1997 all case records were reviewed to determine whether tumor had recurred in any patient, and PR status was correlated with tumor recurrence. Of the 62 tumors, 60 were benign, and of the benign tumors 29 (48%) were PR positive. Patients harboring 14 of the 60 benign tumors were lost to follow up. Of the 46 tumors included in the final analysis, 13 were recurrent (all within 5 years) and 33 were nonrecurrent. Of the 33 nonrecurrent tumors, 14 had not recurred 5 to 10 years postresection and 19 had not recurred after more than 10 years. Chi-square analysis of the results did not show an association between recurrence and patient's sex, extent of resection, histological subtype, or tumor site but did show an association between recurrence and PR negativity (p = 0.013).

CONCLUSIONS

The results indicate that benign meningiomas that are PR positive are less likely to recur, a finding that has prognostic and therapeutic implications.

DNA ploidy and cell-cycle analysis in intracranial meningiomas and hemangiopericytomas: a study with high-resolution DNA flow cytometry

Although various DNA flow-cytometric studies have been performed on meningiomas, the role of DNA ploidy and the S-phase fraction (SPF) in predicting biological tumor behavior remains unresolved. Discrepant results in earlier studies might be due to different preparing, staining and measuring techniques; different quality standards; and lack of sophisticated computer software. In this study, high-resolution DNA flow cytometry using the DNA-specific dye DAPI (4', 6'-diamidino-2-phenylindol) was performed on stored frozen tissue from 128 microsurgically resected meningiomas and 7 hemangiopericytomas, including 17 recurrent meningiomas and 4 recurrent hemangiopericytomas. The computer software Multicycle 2.5 was used to determine the ploidy level and to perform cell-cycle analysis. DNA aneuploidy and SPF were significantly higher in atypical, anaplastic and recurrent meningiomas and correlated well with histopathological features such as focal necrosis, infiltration of dura mater and mitotic activity. Among 128 meningiomas, 42 had additional DNA aneuploid stem lines. No association between hypo- and hyperploidy and either histological subtype or clinical outcome was found. In 7 hemangiopericytomas, SPF was significantly higher compared to the benign meningioma group, while only 1 tumor was aneuploid. In all 42 DNA aneuploid tumors, cell-cycle analysis was performed separately for the euploid and aneuploid stem lines. The proliferation parameters (SPF, G2/M phase) were significantly higher in the DNA aneuploid stem lines. DNA ploidy and SPF are thus useful indicators of different biological behavior within identical histological subgroups in meningiomas.

Meningioma grading: an analysis of histologic parameters

Histologic grading of meningiomas has prognostic and sometimes therapeutic implications, but diagnostic criteria for atypical meningioma are vague, and the significance of brain invasion in the determination of malignancy remains controversial. We reviewed our experience with 581 patients whose meningiomas were resected at Mayo Clinic during the years 1978 through 1988. All patients were followed until death or a median of 9.0 years. Ten histologic parameters were assessed and compared with recurrence-free survival. On univariate analysis, six variables were associated with recurrence, although most were statistically significant only in the subset of patients having undergone gross total tumor resection. On multivariate analyses, the most significant parameters were histologic brain invasion (when assessable) and maximal mitotic rate of at least four per 10 high-power fields (HPF). Also significant were combinations of at least three of the following four parameters: hypercellularity, architectural sheeting, macronucleoli, and small cell formation. Proposed grading criteria based on these findings yielded 81% classic, 15% atypical, and 4% brain invasive meningiomas with respective 5-year recurrence rates of 12%, 41%, and 56%. There was no association between histologic grade and either extent of surgical resection or patient age. However, male sex was associated with high-grade (atypical/brain invasive) tumors. Too few frankly anaplastic meningiomas were encountered for statistical analysis. Brain invasion and an increased mitotic index (at least four per 10 HPF) are the most powerful histologic factors prognostic for recurrence in meningiomas. We propose an objective definition for atypical meningioma based on our data. Because the difference in recurrence rates for brain invasive and atypical meningiomas was not statistically significant, it could not be determined whether brain invasion alone warrants a designation of malignancy. Likewise, we were unable to determine what constitutes histologic anaplasia due to the rarity of such cases.

High PCNA index in meningiomas resistant to radiation therapy

PURPOSE

Meningiomas are common intracranial tumors, often well controlled with surgical resection alone. While the efficacy of radiation therapy in improving local control and progression-free survival is well documented, prognostic data substantiate factors that are predictive of poor local control following definitive radiation therapy. PCNA is a DNA polymerase expressed at the highest levels in the S-phase, the most resistant portion of the cell cycle to ionizing radiation in vitro. We investigated the possible correlation between the levels of PCNA expression and the clinical outcome of patients treated with definitive radiation therapy.

METHODS AND MATERIALS

Archival tissue was collected from 33 cases of meningioma treated at our institution for definitive radiation therapy between 1970 and 1990. Age-matched normal meningeal tissue and asymptomatic meningiomas removed at autopsy served as tissue controls. A standard ABC immumoperoxidase technique employing antibodies to PCNA, PC-10 (Dako, California) was used to stain specimen slides for PCNA. PCNA index was defined as the number of positive nuclei per 10 high-power fields at 400x magnification. Two independent observers scored the slides without prior knowledge of the cases at hand.

RESULTS

Patients with high PCNA index were less likely to be controlled by therapeutic radiation (p < 0.001, Kaplan-Meier). All patients with a PCNA index greater that 25 failed radiation therapy. Using multivariate analyses, malignant (but not atypical), histology and PCNA index were significant predictors of progression following radiation therapy (p < 0.05, log rank).

CONCLUSION

PCNA index may be a useful adjunct to more standard histopathologic criteria in the determination of meningioma local control and progression-free survival following therapeutic irradiation. Data on a more expanded population evaluated on a prospective basis will be needed before such criteria are routinely employed in the clinical setting.

Progesterone and estrogen receptors in meningiomas: prognostic considerations

Meningiomas often contain steroid hormone receptors, but the correlation of receptor presence with patient outcome or mitotic index is unclear. Intracranial meningiomas from 70 patients (27 males and 43 females, mean age 52.9 + 1.7 years [mean +/- standard error of the mean], range 15-78 years) were evaluated immunocytochemically for female sex hormone receptors using specific monoclonal antibodies. Prognostic correlations were determined using statistical analyses that included clinical and histological variables. Twenty-eight tumors were benign, 27 had atypical features, and 15 were malignant. Thirty tumors were meningotheliomatous, 11 were fibroblastic, 28 were transitional, and one was secretory. Twenty-nine of the 70 primary tumors recurred (mean interval to recurrence 50.1 +/- 10 months). The mean progression-free follow-up period for patients without recurrence was 82.1 +/- 7.7 months. Nuclear staining for the progesterone receptor (PR) was found in 58 cases (83%) and PR status was scored as 0 (0% nuclei positive), 1 (< 1%), 2 (1-9%), 3 (10-49%), or 4 (> 50%). Only six tumors (8.6%) contained nuclear estrogen receptor (ER) staining, which was limited to a small number of nuclei (< 1%). Fisher's exact test (two-tailed) showed an inverse correlation between tumor grade and PR staining score (p < or = 0.001), with 96% of benign and 40% of malignant meningiomas containing PR-positive nuclei. No correlation between age or histological subtype and PR score was detected. Meningiomas from female patients had more PRs (p < or = 0.05). Analysis of variance revealed that the mitotic index (total counts of mitoses per 10 high-power fields) for tumors with 0 PR staining (18 +/- 4.4) was higher (p < or = 0.0001) than for those with PR scores of 1 to 4 (4.3 +/- 1.9, 5.1 +/- 2, 2.2 +/- 0.8, and 1.7 +/- 0.9, respectively). Univariate analysis indicated that the absence of PR, high mitotic index, and higher tumor grade were significant factors for shorter disease-free intervals. Multivariate analysis showed that a three-factor interaction model, with a PR score of 0, mitotic index greater than 6, and malignant tumor grade, was a highly significant predictor (p < or = 0.0001) for worse outcome in patients harboring meningiomas. These data indicate that the presence of PRs, even in a small number of tumor cells, is a favorable prognostic factor for meningiomas.

MIB-1 staining index and peritumoral brain edema of meningiomas

BACKGROUND

Growth rates and tumor aggressiveness of meningiomas are thought to be closely related to brain edema development. However, histopathologic data alone are not consistently accurate predictors of the behavior and clinical course of a meningioma.

METHODS

The authors examined 57 histologically proven intracranial meningiomas to identify factors, including growth fractions determined by MIB-1 immunostaining, that may influence the development of meningioma-associated peritumoral brain edema. There were 54 benign, 2 atypical, and 1 anaplastic meningiomas. The MIB-1 staining index (SI) percentage was defined as the number of MIB-1 positive cells divided by the total number of tumor cells in a 1.037-square millimeter area on the slide. The extent of peritumoral brain edema was determined using preoperative magnetic resonance imaging. The extent of edema was classified as Grade 0,1, or 2 (GR0, GR1, or GR2), in order of increasing severity.

RESULTS

The MIB-1 SIs of the 57 cases ranged from 0.06-6.8% (median, 0.80%). There were 26 GR0, 20 GR1, and 11 GR2 edema cases. The MIB-1 SI rose in order of increasing edema severity. There was a statistically significant correlation between the MIB-1 SI and the extent of brain edema (P<0.0001), and also between the tumor size and the extent of brain edema (P=0.001). Meningothelial and atypical/anaplastic meningiomas were associated with peritumoral brain edema more often than any other subtype (P<0.005).

CONCLUSIONS

Growth fractions, as determined by MIB-1 immunostaining, rise with increasing severity of peritumoral brain edema, indicating a close relationship between tumor aggressiveness and edema development.

Prognostic significance of nuclear DNA content in human meningiomas: a prospective study

Flow cytometric DNA analyses were performed to study the correlation between alterations of nuclear DNA content and clinical aggressive tumour behaviour in 134 cranial meningiomas. Forty-one meningiomas revealed an aneuploid DNA content with a distribution of n = 24 in benign, n = 12 in atypical and n = 5 in anaplastic tumours. Aneuploid DNA content was correlated with a significantly higher amount of histomorphological criteria like evidence of mitoses, necrosis, infiltration and increased cellularity. There was a significantly higher Ki 67 proliferation index in the aneuploid meningiomas in comparison to the diploid tumour group. The rate of aneuploid cell-lines was increased in recurrent tumours. No tumour recurrence could be found in diploid meningiomas during follow up (mean 37 months, range 22-46 months). However eight of forty-one aneuploid tumours showed meningioma recurrence. Nuclear DNA content has an important significance in predicting risk of recurrence and poor clinical outcome after benign meningioma surgery.

Significance of proliferating cell nuclear antigen in predicting recurrence of intracranial meningioma

It is well known that the histological appearance of meningiomas often fails to predict accurately the clinical behavior of the tumor. Therefore, attention has turned from tumor histology to tumor biology. Proliferating cell nuclear antigen (PCNA), a cell cycle-regulated protein, has been recently characterized as the cofactor of DNA polymerase-delta, an enzyme required for DNA replication. The rate of synthesis of PCNA directly correlates with the proliferative state of cells. Immunohistochemical labeling of this antigen is now possible with monoclonal antibodies that allow for its demonstration in routinely fixed, paraffin-embedded specimens. In this study, the PCNA labeling index (LI) was determined for 83 meningiomas, including tumors with both benign and malignant clinical courses and with benign, atypical, and malignant histologies, apparent after total or subtotal resections. No statistical difference was found between the LI on recurrence and that found at initial presentation. In addition, stepwise multivariate regression analysis failed to identify any combination of factors (age, gender, race, age of specimen, tumor histology, Simpson grade of resection) that contributes to the predictive strength of the PCNA LI for tumor recurrence. However, for LIs less than 2%, only one of 26 gross totally resected tumors recurred (mean follow up 53 months); for LIs more than 7%, five of 13 gross totally resected tumors recurred (mean follow up 55 months). The difference in recurrence rates between gross totally resected meningiomas with PCNA LIs less than 2% and those with PCNA LIs more than 7% achieved statistical significance with a Fisher's exact probability equaling 0.011. The authors conclude that quantitative PCNA labeling of meningiomas is a promising technique that can provide meaningful prognostic information.

Nuclear morphometry and DNA densitometry of human gliomas by image analysis

In 48 patients with gliomas in whom complete clinical follow-up was obtained, DNA ploidy was evaluated by using formalin-fixed paraffin-embedded tissues and by means of image analysis. The mean DNA indices, determined by averaging DNA indices of all tumor cells in a tumor, were mainly affected by mean DNA indices of the nuclei of SG2M phase tumor cell (including S phase and G2M phase cells) (SG2M DNA indices) and that mean DNA indices correlated with the SG2M phase fraction. The SG2M DNA indices and the percentage of tumor cells with S phase and G2M phase were higher in high grade gliomas including anaplastic glioma and glioblastoma multiforme than in low grade gliomas. Patients with G2M-hypertetraploid tumors demonstrated a shorter time to tumor progression than those with G2M-tetraploid in high grade glioma. Morphometrically, the nuclei of SG2M phase glioma cells were larger and more deformity than those of G0G1 phase (including G0 phase and G1 phase cells) cells. The G2M-hypertetraploid tumors were highly malignant and demonstrated large nuclei, greater nuclear deformity, and a higher proliferative potential. The G2M-tetraploid gliomas demonstrated a shorter time to tumor progression in cases whose the SG2M fraction was large. In contrast, G2M-hypotetraploid gliomas revealed an insignificant trend towards a longer time to tumor progression than those associated with tetraploid and hypertetraploid gliomas. We emphasize herein the prognostic importance of the SG2M phase cell, as well as other proliferation indices.

Repeated multifocal recurrence of grade I, grade II, and grade III meningiomas: regional multicentricity (primary new growth) or metastases?

In this study 48 patients with histologic grade I and 41 with grade II/III meningiomas were reviewed retrospectively for the occurrence of multifocal tumor masses in relation to recurrence. Regional multicentric tumor masses were increasingly seen in progressive disease with repeated recurrence and occurred significantly more frequently in grade II/III compared to grade I meningiomas. Small microscopic tumor extensions along the subdural space around the tumor bulk, defined as tumor spurs, could be documented as an alternative form of multifocal disease. The occurrence of these spurs was associated with recurrence. In nearly all cases the multifocal disease was limited to the vicinity of the primary or previous tumor site. In three patients with grade III meningiomas however, at recurrence distant tumors could be found. These were interpreted as drop, cerebrospinal fluid and hematogenic metastases, respectively. In these three cases tumor spurs were documented in previous operations. It is concluded that not only primary new growth in a tumor that virtually from the beginning already has a regional multifocal origin, but also the spread of tumor cells along the subdural space forming tumor spurs, as well as distant metastases, plays an important role in recurrent meningioma.

Cell kinetic analysis in pediatric brain and spinal tumors: a study of 117 cases with Ki-67 quantitation and flow cytometry

We present cell kinetic data including Ki-67 quantitation and flow cytometry on 117 pediatric brain/spinal cord tumors and review the literature. Although, in general, these proliferation indices are in agreement with the histologic grade, they are useful in prognostication in some instances when the histological features of malignancy are equivocal. Specific examples in which flow cytometry may prove particularly useful in this context are childhood ependymomas, which do not show frank anaplasia but have cellular foci with focal increase in mitoses, and choroid plexus neoplasms, where elevated S phase fractions have been associated with an adverse outcome. Thus Ki-67 quantitation and flow cytometry not only serve as useful adjuncts to conventional histologic grading but also in specific instances may provide new information on tumor prognosis.

The biology and pathology of selected skull base tumors

This paper describes the pathobiology of some of the more common skull base tumors. In addition to clinicopathologic features, emphasis is placed upon methods of diagnosis utilizing immunoperoxidase stains and molecular markers that may or may not impact upon prognosis.

Meningiomas of the cranial base

Treatment objectives for meningiomas of the cranial base include relief of neurologic disability and prevention of clinical progression or recurrence with the least morbidity. Recent advances in skull base surgical techniques, through an appreciation of skull base anatomy and institutional specialization, have contributed major improvements to the outlook for patients with these tumors, and previously inoperable cases may now often be removed completely with acceptable risk. Since significant morbidity may be incurred during surgical resection of these difficult lesions, especially in terms of cranial nerve dysfunction, the value of aggressive surgical resection must be weighted against the often indolent natural history of these lesions, and must be individualized in each patient. Completeness of resection is the major prognostic factor determining the outcome of patients with typical benign meningiomas in terms of length of survival, risk of recurrence, and neurological disability. Various means of prognosticating the growth potential of a given tumor are being investigated, though none have yet been confirmed for their predictive value in typical, histologically benign meningiomas. The role of external beam radiotherapy has not been subjected to adequately controlled, prospective studies, and there is currently insufficient followup to assess the risks and benefits of stereotactic radiosurgery. Advances in the clinical management of tumors of the skull base has had perhaps the greatest impact for patients with meningiomas who constitute a large portion of tumors seen in these locations. Although the majority have benign histological features, skull base meningiomas can present a formidable challenge due to their proximity to vital structures, surgical inaccessibility, and occasional aggressive features. The combination in recent years of advances in skull base surgical techniques, adjuvant therapy, and rehabilitation methods have dramatically improved the outcome for these tumors.

Clinical evaluation of DNA index in human brain tumors

We evaluated the DNA index values in 28 brain-tumor patients showing DNA aneuploidy on the DNA histogram obtained by flow cytometry. In 17 cases among them, the DNA index values were compared to BUdR labeling indices (BUdR-LI). Average DNA indices of individual tumor types were 1.89 +/- 0.10 (6 glioblastomas multiforme), 1.93 +/- 0.05 (4 anaplastic astrocytomas), 1.68 +/- 0.09 (3 malignant meningiomas), 1.24 +/- 0.03 (7 meningiomas), 1.19 +/- 0.05 (2 pituitary adenomas) and 1.86 +/- 0.24 (6 metastatic brain tumors). Slow-growing tumors such as meningioma and pituitary adenoma, had lower values than malignant tumors, except a case of a metastatic brain tumor. All malignant meningiomas had higher DNA index values than the other meningiomas. No difference was observed between the DNA index values of glioblastomas multiforme and anaplastic astrocytomas. DNA index values were correlated with BUdR-LI values (p < 0.05), and seven cases with low DNA index values (1.13-1.31) had low BUdR-LI values of less than 1%. Others with high DNA index values of 1.44 or more had high BUdR-LI values of 3.5% or more. These results suggest that high DNA index values is related to tumor malignancy, and despite the presence of some disparities, many slow-growing brain tumor has low DNA index values.

A sequential cell kinetic study of meningioma cells in primary explant culture using bromodeoxyuridine

The present study was undertaken to evaluate the sequential BrdU-LI at weekly intervals upto four weeks in 18 primary explant cultures of meningiomas. This revealed three distinct patterns of growth which could be arbitrarily defined as 'degenerating' (group I), 'proliferating' (group II) and 'adaptive' (group III) types. Interestingly two cases of malignant and two of recurrent meningiomas fell into the 'degenerating' group I pattern. The possible explanations for the observed relatively higher in vitro LI values compared to lower in vivo values as reported in the literature and the theoretical implications of the three distinct patterns of sequential LI values are discussed.

Relationship between proliferative activity and ploidy level in a series of 530 human brain tumors, including astrocytomas, meningiomas, schwannomas, and metastases

By identifying six DNA histogram types (diploid, hyperdiploid, triploid, hypertriploid, tetraploid, and polymorphic) in a series of 206 astrocytic tumors, we showed recently that patients with hypertriploid astrocytic tumors have a better possibility of survival than patients with other DNA histogram-type related tumors. In the present work DNA histogram type and proliferation index (S-phase fraction) are characterized in a series of 530 adult tumors from the central and peripheral nervous systems. Of these 530 tumors, there were 79 nerve sheath tumors, 181 meningiomas, 221 astrocytic tumors, and 49 metastases. Analysis was performed by means of digital cell image examination of Feulgen-stained nuclei from formalin-fixed, paraffin-embedded tumors. The data reveal that there was a majority of diploid tumors (66%) in the primary tumor group (nerve sheath tumors, meningiomas, and astrocytic tumors), while aneuploid tumors were in a marked majority (90%) in the secondary (metastatic) brain tumor group, with a predominance (47%) of the polymorphic tumor type. Independently of tumor histopathologic group, the hypertriploid-type tumors proliferated less actively than the five other types. Such a feature might partly explain the better prognosis associated with hypertriploid astrocytic tumors as compared with what occurs with respect to the other DNA histogram-type related tumors.

Prediction of recurrence in pituitary tumours: a flow cytometric study using in vivo bromodeoxyuridine

Although most pituitary tumours are regarded as benign, there is a significant risk of local recurrence and a few are frankly malignant. The prediction of clinically aggressive behaviour by histopathological means is inadequate and the selection of patients for postoperative radiotherapy has often been empirical. The flow cytometric analysis of the DNA content of certain intracranial tumours has suggested a correlation between a high proliferative index and a tendency to recur. The in vivo administration of bromodeoxyuridine (BUdR) yields a reliable and accurate S-phase labelling index and evaluation by flow cytometry allows a much greater and therefore more representative number of cells to be examined. We report our results for the flow cytometric evaluation of the S-phase fraction in a group of 11 human pituitary tumours following the preoperative administration of BUdR and discuss the correlation between high values of S-phase fraction and clinically aggressive behaviour. Initial results suggest a correlation between radiological evidence of tumour invasion and an S-phase greater than 2%.

Proliferating cell nuclear antigen (PCNA) in atypical and malignant meningiomas

Because it is not easy to determine the tumor status of meningiomas by current diagnostic procedures, we investigated these tumors immunohistochemically using the monoclonal antibody PC 10. This antibody recognizes a fixation- and processing-resistant epitope of the proliferating cell nuclear antigen (PCNA), which is a 36-KD nuclear antigen associated with the cell cycle. We studied paraffin-embedded and formalin-fixed tissue specimens of a group of 21 atypical/malignant meningiomas together with 18 benign meningiomas. PCNA staining results were compared with the mean number of silver-stained nucleolar organizer region-associated proteins (AgNORs), tumor grading, and mitotic indices of these tumors. The percentage of PCNA-positive cells was found to range between 0.1% and 40%, irrespective of the tumor grade. When all tumors were collectively considered, no positive correlation was found between PCNA scores and histologic grading and only a weak one between PCNA score and mitotic index. A higher correlation was seen between AgNOR counts and tumor grading. Our results suggest that PCNA labeling and histologic grading seem to be independent parameters. The correlations found between AgNOR counts and tumor grading should be substantiated in further series.

Meningiomas: clinical implications of a high proliferative potential determined by bromodeoxyuridine labeling

The clinical behavior of meningiomas with a high proliferative potential was analyzed to determine if the bromodeoxyuridine (BUdR) labeling index (LI) could be used to predict recurrence and the time to reoperation. Each patient received an intraoperative infusion of BUdR to label cells in DNA synthesis; the percentage of S-phase cells, or BUdR LI, of each tumor was determined immunohistochemically. Of 178 meningiomas studied, 53 had BUdR LIs greater than or equal to 1%. Of these 53 tumors, 21 were diagnosed histopathologically as malignant meningioma. Twenty-two percent of nonmalignant tumors and 81% of malignant tumors were recurrent or recurred after the BUdR study; repeat studies were performed in four patients. The mean BUdR LI of recurrent tumors was significantly higher than that of the nonrecurrent tumors [3.9 +/- 2.6 versus 1.9 +/- 1.0% (SD), P less than 0.005]. The recurrence rate was 100% for tumors with LIs greater than or equal to 5%, 55.6% for those with LIs of 3 to 5%, and 30.6% for those with LIs of 1 to 3%; the percentages of malignant meningiomas in these groups were 88%, 78%, and 19%, respectively. Logarithmic regression analysis showed that the time to reoperation (in months) can be predicted from the BUdR LI as: 70.0 x LI (%)-1.2 (R = 0.76). This formula can be used to estimate the doubling time of individual tumors and to predict the period of greatest risk of recurrence of meningiomas with a high proliferative potential.

Correlation of in vitro bromodeoxyuridine labeling index and DNA aneuploidy with survival or recurrence in brain-tumor patients

There are no previous reports correlating the in vitro bromodeoxyuridine (BUdR) labeling index (LI) with the clinical outcome in patients with brain tumors. The reliability of the LI as a predictor of patient survival or recurrence was examined in this study of 66 human brain tumors (19 gliomas, 18 meningiomas, and 29 others). Anti-BUdR staining was performed on surgically extirpated tumor tissue that had been treated with BUdR as previously described. Correlation of the BUdR LI with patient survival or tumor recurrence rate was carried out by the method of Kaplan and Meier. Deoxyribonucleic acid (DNA) aneuploidy was estimated in 52 cases. The results of this study indicate that BUdR LI values correlated well with the clinical course of patients with brain tumor. In comparison with patients with higher LI's, there was both a significantly higher survival rate for tumors other than meningiomas and a higher recurrence-free rate for meningiomas in patients with LI's of less than 4% and 1%, respectively. Although there was a tendency for patients without tumor aneuploidy to show better survival data than the others, no statistical difference was observed. These results suggest that the in vitro BUdR labeling method is reliable for prediction of a patient's prognosis, whereas prognosis on the basis of DNA aneuploidy alone is uncertain.

Tumors of the meninges: proposed modifications of the World Health Organization classification

The present WHO classification of meningiomas has served us well. In keeping with the adage, "if it ain't broke, don't fix it," alterations should be made with due caution. These proposed modifications of the WHO classification are prompted by advances in our understanding of the pathobiology of meningeal neoplasms, as well as a need for an orderly scheme based upon factors of clinical importance. The author is well aware, that given the vastly differing technologies available to those utilizing the "blue book," its application must have a basis in routine histology rather than in "high-tech" procedures. No classification is ideal, but the modifications suggested represent a compromise between the pathologist's need for a complete morphologic exposition and the clinician's desire for a concise classification of therapeutic and prognostic significance.

Immunohistochemical profile of meningiomas and their histological subtypes

Seventy-seven cases of meningioma (15 with single or multiple recurrences), selected on the basis of their histologic subtypes, and nine cases of neurilemoma were analyzed immunohistochemically for the presence of the five classes of intermediate filament proteins, neuron-specific enolase (NSE), protein S-100, epithelial membrane antigen (EMA), and HNK-1 (Leu-7). Most antibodies were studied with the alkaline phosphatase-antialkaline phosphatase method. The peroxidase-anti-peroxidase and avidin-biotin-complex methods were used for Leu-7 and NSE, respectively. Meningiomas were subdivided into groups showing cytokeratin or protein S-100 positivity. Coexpression of these two markers was rare (5%) and occurred in meningotheliomatous meningiomas only. Only in these cases was cytokeratin expression more frequent than in meningiomas taken together (33% versus 20%). In contrast, protein S-100 expression was less frequent (46% versus 60% on average). In fibrous meningiomas, both cytokeratins and NSE were expressed less frequently than on average (11% versus 20%, 67% versus 88%, respectively). Protein S-100 occurred in a higher percentage of cases. Transitional meningiomas did not show cytokeratin expression. Protein S-100 occurred in a higher percentage of cases. Transitional meningiomas did not show cytokeratin expression. Protein S-100 was expressed slightly more often than in the other subtypes. Psam-momatous meningiomas coexpressed more markers than any other subtype. Hemangioblastic and hemangiopericytic forms did not stain for EMA, but otherwise showed a staining profile similar to that of meningiomas. HNK-1 was expressed in 29% of meningiomas, particularly among tumors with anaplastic histologic features. There was no marker that retrospectively indicated impending recurrences.

Bromodeoxyuridine labeling study of intracranial meningiomas: proliferative potential and recurrence

Ninety-six patients with intracranial meningiomas and two with hemangiopericytic variants received a 30-min intravenous infusion of bromodeoxyuridine (BrdUrd), 200 mg/m2, before tumor removal. Excised tumor specimens were stained by the indirect immunoperoxidase method to determine the BrdUrd labeling index (LI), or percentage of cells in DNA synthesis. The BrdUrd LI was less than 1% in 63 (86.3%) of 73 nonmalignant meningiomas and less than 1% in 20 (87%) of 23 malignant meningiomas. Of 23 malignant meningiomas 11 were recurrent tumors; 8 patients had recurrence 3 to 33 months after the study. The recurrence rate was 100% (five of five) in patients whose tumors had a BrdUrd LI greater than 5%, 44% (11 of 25) in those with a BrdUrd LI 1% to 5%, and 6.1% (4 of 66) in those with an LI less than 1%. Thus, meningiomas with a BrdUrd LI greater than 1% may grow faster and recur more frequently. Among patients with malignant meningiomas, the mean time to recurrence after the study was 7.5 months in those with a BrdUrd LI greater than 5% and 20.2 months for those with an LI 1% to 5%. The mean time to recurrence was 97.8 months in patients with nonmalignant meningiomas. Both hemangiopericytic variants were recurrent and showed LIs of 0.5% and 4.1%; the former tumor recurred 8 years after complete resection, while the latter recurred three times in 3.5 years. Thus, the proliferative potential of intracranial meningiomas as reflected by the BrdUrd LI appears to be a prognostic variable that can help to elucidate the biological behavior of individual meningiomas.

Loss of the Y chromosome in meningiomas. A molecular genetic approach

Loss of the Y chromosome in meningiomas from 17 male patients was examined by cytogenetic analysis and by Southern blot hybridization with a series of Y-specific DNA probes. Cytogenetic analysis revealed loss of the Y chromosome in seven of 17 (41%) of the tumors whereas Southern blot hybridization showed loss of Y-associated sequences in only three of 17 (18%). Although the incidence of Y-chromosome loss was less by Southern blot hybridization than by cytogenetic analysis, the finding that loss of Y is present in the original uncultured tumor specimen suggests that a gene or genes on the Y chromosome may play a role in growth control of meningioma cells, and loss of this gene may be associated with tumor progression. The difference in the incidence of Y loss between the two methods indicates that both methods should be used when examining chromosome losses.

The prediction of recurrence in meningiomas. A flow cytometric study of paraffin-embedded archival material

Despite the complete macroscopic excision of meningiomas, there is a significant rate of recurrence approaching 20% at 20 years. The prediction of recurrence by clinical and histopathological means is inadequate. Flow cytometric analysis of deoxyribonucleic acid (DNA) in meningiomas has shown a correlation between a high proliferative index based on tumor cell-cycle stage (%S + %G2/M) and clinically aggressive behavior. Accordingly, the DNA analysis of meningioma tissue may be of value in predicting recurrence of these tumors. To test this hypothesis, the DNA of paraffin-embedded archival tissue from known recurrent meningiomas was compared with an age- and sex-matched nonrecurrent group. Both groups had comparable follow-up periods. Forty patients with total macroscopic removal at the time of surgery were analyzed. The paraffin blocks of these tumors were retrieved and reclassified histologically according to the World Health Organization system. Sections were then taken for flow cytometric study. The DNA analysis showed that the proliferative index of the recurrent group was significantly higher than that of the nonrecurrent group (p less than 0.002), although the histological subtyping of the two groups was similar. These results support the suggestion that flow cytometry may be of value in the prediction of recurrence of histologically benign, macroscopically removed meningiomas.

Flow-cytometric DNA analysis and immunohistochemical measurement of Ki-67 and BUdR labeling indices in human brain tumors

Cell proliferation potential was assessed by measuring the labeling indices of the monoclonal antibody Ki-67 and of 5-bromodeoxyuridine (BUdR), and the cellular deoxyribonucleic acid (DNA) content in 48 human brain tumors. The diagnostic and prognostic value of flow-cytometric DNA analysis was also evaluated using ethanol-fixed paraffin-embedded BUdR-labeled specimens; these were the same specimens as were used for measuring the BUdR and Ki-67 labeling indices. Both the Ki-67 and the BUdR labeling indices correlated with the degree of malignancy estimated from conventional histological preparations. The Ki-67 labeling index was 1.7 times greater than the BUdR labeling index. The relationship of DNA aneuploidy to the labeling indices or to morphology in cases of glioma was examined. All of the tumors with an aneuploid line corresponded to malignant glioma classified by histological criteria, although malignant glioma did not always show DNA aneuploidy. In addition, the cases with aneuploid lines showed high BUdR and Ki-67 labeling indices. The cell kinetic data, which indicate the biological character of tumors, allowed prediction of the prognosis of the patients with gliomas. In contrast, despite the presence of an aneuploid line, three of 13 meningiomas showed a benign histological pattern without an aggressive clinical course, and neither the Ki-67 nor the BUdR labeling index was high. These results indicate an unequivocal relationship between DNA aneuploidy and clinical behavior; in general, both labeling indices may prove to be objective indicators of the outcome of patients with brain tumors.

DNA-determination in the clinical management of patients with meningioma or haemangioblastoma

The histopathology and clinical course of 15 benign (grade I) and nine anaplastic (grade II-III) meningiomas was reviewed and compared with the nuclear DNA distribution patterns of the tumour cells as determined by Feulgen staining with ensuing image and flow cytometry. In addition, eight haemangioblastomas were studied. One benign meningioma, three anaplastic meningiomas and two haemangioblastomas were aneuploid. The outcome could be well predicted from standard histopathological criteria and a critical evaluation of the extent of removal at operation. The determination of nuclear DNA contents did not add further information useful in the management of these meningioma patients. Histopathologically aggressive or frankly anaplastic tumours had a bad outcome. The clinical results underline the importance of aggressive treatment of anaplastic meningiomas.

Cytogenetic studies in 50 meningiomas

In a series of 50 meningiomas, cytogenetic studies showed that almost half had a normal diploid karyotype. The remainder had monosomy 22, some with a normal diploid line also present. The initial monosomy was often followed by further chromosome loss, and occasionally by structural abnormalities, some with distinctive characteristics. Chromosomes most often involved in structural rearrangements were 1, 14, 10, and 19, and those most often lost were 17 and Y. The type of chromosome abnormalities seen were similar to those described for senescent human cell cultures, which suggests that common chromosomal mechanisms may be operative in benign tumors and senescent cells. Although meningiomas occur more commonly in females, the chromosomally abnormal tumors are distributed evenly between males and females. Within the group of tumors with structural chromosomal abnormality, there seems to be a bias toward meningotheliomatous histology, but otherwise the karyotype changes seen independent of the histologic type of tumor.