Cytogenetic and proliferative potentials in meningiomas

Cytogenetic analysis and Ki-67 staining index (SI) were performed on the series of 51 meningiomas, to estimate the relationship between the extent of chromosomal changes and the growth potential of tumors. The tumors were classified according to histological subtype (22 meningiotheliomatous, 15 transitional, 12 fibroblastic and 2 angiomatous) and grade (40 benign, 5 atypical and 6 malignant ones). There was no significant difference in the complexity of chromosomal changes among the histologically distinct tumor subtypes. In contrast, there was a significant association between the number of chromosomal abnormalities and tumor grade. Normal karyotypes were found in 50% and complex in 20% of benign tumors. All grade II or III tumors revealed complex karotype. The tumors classified as benign revealed significantly lower mean Ki-67 SI than atypical or malignant ones (1.6%, 7.4% and 14.7%, respectively). However, within tumors classified as benign, mean Ki-67 SI of these with normal or simple karyotypic changes did not differ significantly from those with complex karyotype (1.6% and 0.9%, respectively). Thus, the extent of genome abnormalities in meningiomas, measured on the chromosomal level, does not relate directly to their proliferative potential.