Prediction of biologic aggressiveness in human meningiomas: a cell kinetic study using bromodeoxy-uridine in cells of primary explant culture

Correlation of histology, cytogenetics and proliferation fraction (Ki-67 and PCNA) quantitated by image analysis in meningiomas

Sixty meningiomas were classified histologically according to the WHO criteria and analyzed cytogenetically. The Ki-67 and PCNA proliferation fractions (PRFs) were assessed by immunhistochemistry. The staining results were quantified by TV-image analysis (Miamed, Leica, Germany). Within meningiomas of WHO-grade II/III and those with complete or partial deletion of # 1p, we found a significantly higher mean and maximal Ki-67 PRFs than in those of WHO-grade I and those with all other karyotypes. This was not the case for PCNA PRFs. No differences in PRFs were detectable between histological subtypes. Although these results were obtained after measurement of five high power fields (HPFs) only, the heterogeneity of PRF distribution within the tumors was high. Even after the measurement of 100 HPFs, the 95% confidence intervals were in a range of 18% to 34.3% PRF. This finding seems to be responsible for the moderate interobserver reproducibility of image analytical determination of PRF (r = 0.74). Nevertheless, there was a good correlation between subjective and objective image analytical assessment of PRF (r = 0.83). The significance of the maximum Ki-67 PRF per specimen implies the possibility of selecting those areas which show the highest fraction of positively stained nuclei for measurement, avoiding the problem of intraslide heterogeneity. Thus the time needed for image analytical quantification may be reduced.

Comparison of MIB-1 (Ki-67) antigen and bromodeoxyuridine proliferation indices in meningiomas

Meningiomas from 40 adult patients were labeled immunohistochemically with monoclonal antibodies to bromodeoxyuridine (BUdR) and the Ki-67 antigen, MIB-1. The meningiomas were classified as classical, or benign (n = 31); atypical (n = 4); or malignant (n = 5). Meningeal sarcomas and hemangiopericytomas were excluded. The patient population consisted of 26 women and 14 men, ranging in age from 26 to 75 years. BUdR proliferation indices ranged from 0% to 5.8%, measurements that were expectedly lower than those for MIB-1, which ranged from 1.5% to 19.3%. MIB-1 proliferation indices were not significantly affected regarding steroid pretreatment or age. These results show a good correlation between the BUdR and MIB-1 proliferation markers (rs = 0.72; P < .0001), which supports the use of anti-MIB-1 as an alternative labeling tool to BUdR for the determination of the proliferation index in meningiomas, thus avoiding the administration of a potentially mutagenic drug.

Triple approach for diagnosis and grading of meningiomas: histology, morphometry of Ki-67/Feulgen stainings, and cytogenetics

With regard to meningioma grading and the recently introduced "atypical" meningioma, we evaluated 160 cases retrospectively by conventional histology and image analysis. For that, the cell nuclei were stained with a Ki-67 (MIB1)/Feulgen-method on paraffin sections, thus enabling the assessment of both the Ki-67 proliferation index and nuclear morphometric features, such as tumour cell arrangement, nuclear pleomorphism, and cellularity. It could be demonstrated that the Ki-67 proliferation index is the most important criterion for distinguishing anaplastic meningiomas (WHO "grade" III) (mean Ki-67 index: 11%) from those of common type (WHO "grade" I) (mean Ki-67 index: 0.7%). The parameter for the "relative volume weighted mean nuclear volume" is another valuable morphometric feature. The "atypical" meningioma (WHO "grade" II) which should represent an intermediate category between common type and anaplastic meningiomas is characterized by a mean Ki-67 proliferation index of 2.1%. Common type meningiomas which comprise almost 50% of the cases of this series have a relapse rate of 9%. "Atypical" and anaplastic meningiomas recurred in 29% and 50%, respectively. Since the term "atypical" meningioma is confusing in the context of tumour grading, the term "intermediate type meningioma" is proposed. Furthermore, the results of cytogenetic analyses of 142 cases of this series were evaluated and compared with the meningioma grades. Thereby, 25 cases disclosed, independent of the typical loss of one chromosome 22, cytogenetic features assumed to be progression-associated, e.g., the gain or loss of different chromosomes and the deletion of the short arm of one chromosome 1 (hyperdiploidy, increased hypodiploidy, 1p-), when correlated to the histological and morphometric findings or the high relapse rate. For meningioma diagnosis and grading, a practical guideline is proposed based upon histology, morphometry (Ki-67), and cytogenetics.

A correlative study of in vivo and in vitro labeling index using bromodeoxyuridine in human brain tumors

The labeling index (LI) of 216 cases of human brain tumors was determined by the immunohistochemical technique with monoclonal antibody to bromodeoxyuridine (BrdU). The proliferative potential of 110 cases was estimated using the intra-operative intravenous infusion of BrdU at a dose of 200 mg/sq m. In another 106 cases, the in vitro technique of incubating freshly resected tumor tissue fragments with 100 microM bromodeoxyuridine was used. The BrdU LI in these tumors was then correlated with the histological types and the data as determined by both the in vivo and in vitro BrdU incorporation were compared. The results indicate that although in vivo and in vitro techniques could possibly provide equivalent data in some histologic types, a clear statistically valid proof however is not apparent from this study.

Rearranged p53 gene with loss of normal allele in a low-grade nonrecurrent glioma

We are studying the p53 gene profile in primary glial tumors by seeking alterations in the hybridization pattern of the tumor DNA probed with a p53 gene probe. This report documents a rearranged p53 gene with loss of the normal allele in a low-grade mixed glioma which has not recurred during 4-year follow-up. The tumor had a low 5-bromodeoxyuridine (BrdU)-labeling index and low AgNOR count. The p53 protein was not detected on immunochemical staining. To our knowledge, this is the first report of an altered p53 gene in a low-grade nonrecurrent glial tumor and highlights the presence of further checks and balances on the control of cell proliferation and other malignancy-associated phenotypes, even in an already-established tumor.

The application of 5-bromodeoxyuridine in the management of CNS tumors

A variety of clinical reports have described the application of the bromodeoxyuridine labeling index as an adjunct to conventional pathological examination of CNS tumors. This index has proven useful in predicting the clinical outcome associated with many such tumors. Furthermore, because of its efficacy as a radiosensitizing agent, bromodeoxyuridine (and the closely related iododeoxyuridine) has been used in combination with radiation therapy for malignant glial neoplasms, with some encouraging results. Although most studies suggest that bromodeoxyuridine is safe, there is evidence that this compound does have potential side-effects, including the observation that it is a mutagen and carcinogen in some experimental systems. A number of new alternative approaches for predicting the clinical outcome of CNS tumors has been developed based on an increased understanding of their molecular biology. However, until such approaches are better characterized, the clinical application of bromodeoxyuridine will continue to play an important role in predicting the clinical behavior of many CNS tumors.

Cell culture studies on human nerve sheath tumors

The main controversy about nerve sheath tumors (NSTs) has been their histogenesis. A Schwann cell origin has been proposed by many investigators for both schwannomas and neurofibromas. However Erlandson and Woodruff observed that while schwannomas appeared to be composed predominantly of Schwann cells, neurofibromas consisted of mainly perineurial cells. In addition, variable numbers of fibroblast-like cells and intermediate cells also have been reported in the 2 lesions. Whether these represent distinct cell types or variants of Schwann cells is still debatable. In an attempt to solve this controversy, the present study was undertaken to observe the morphology and the behaviour of these tumors in culture. These studies showed that all nerve sheath tumors are basically of Schwann cell origin and that intermediate cells and fibroblasts are variants of Schwann cell. Tissue culture studies done chiefly on schwannomas showed that the morphological features of schwannomas are preserved in 'in vitro culture' condition and therefore the difference between neurofibroma and schwannoma appears to be due to inherent differentiating property of the Schwann cells along with some environmental stimulus.

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.

Morphological appearance, growth kinetics and glial fibrillary acidic protein (GFAP) expression in primary in vitro explant culture of astrocytic neoplasms

Astrocytomas of different grades of malignancy were cultured as primary explant and their sequential growth pattern, glial fibrillary acidic protein (GFAP) expression and labelling index (LI) using bromodeoxyuridine (BrdU) were assessed and correlated with the grade of malignancy of the original tumor tissue. Low-grade astrocytomas showed patterns of growth that diverged from anaplastic astrocytomas and glioblastoma multiforme. The GFAP expression decreased with increasing time in culture in all astrocytomas irrespective of the grading. Maximum GFAP was, however, expressed in the morphologically well-differentiated stellate cells. Contrary to expectations, lower BrdU LI was observed in glioblastoma multiforme in comparison to low-grade astrocytomas, which suggests some unidentified mechanism of differentiation in vitro for astrocytomas of higher grade of malignancy. Hence, in contrast to reported literature on the prognostic value of studies on primary cultures, the present study cautions the extrapolation of the in vitro findings for astrocytomas.