Ki-67 immunoreactivity in human central nervous system tumors: a study with MIB 1 monoclonal antibody on archival material.

Paraffin-embedded surgical specimens from 136 primary human central nervous system (CNS) tumors, including 50 meningiomas, 24 astrocytomas, 26 anaplastic astrocytomas, 9 glioblastomas, 8 oligodendrogliomas, 4 ependymomas, 1 anaplastic ependymoma, 2 subependymomas, 9 medulloblastomas, and 3 paragangliomas, were immunostained, following microwave processing, using a streptavidin/peroxidase method and the MIB 1 monoclonal antibody (mAb) against the Ki-67 antigen. The following mean Ki-67 labeling index (LI) values +/- SD were found: meningiomas, 2.47 +/- 1.83; astrocytomas, 2.03 +/- 2.03; anaplastic astrocytomas, 12.80 +/- 6.29; glioblastomas, 14.57 +/- 6.77; oligodendrogliomas, 5.06 +/- 4.78; ependymomas, 2.63 +/- 2.58; anaplastic ependymoma, 6.89; subependymomas, 1.79 +/- 1.54; medulloblastomas, 18.77 +/- 9.65; and paragangliomas, 2.19 +/- 2.51. Our findings indicate that while malignant CNS tumors always exhibited high Ki-67 LI values, and benign CNS tumors generally displayed lower values, increased immunoreactivity for Ki-67 epitopes (Ki-67 LI higher than 4) was noted in a number of meningiomas, astrocytomas, ependymomas, oligodendrogliomas and paragangliomas, contrasting with their benign histological features. Further investigations of the Ki-67 immunoreactivity in CNS tumors and systematic correlation with the postoperative follow-up of patients are necessary to determine the value of Ki-67 LI in predicting the biological behavior of CNS neoplasms.