Cell kinetics of the malignant evolution of meningothelial meningioma.

A meningotheliomatous meningioma occurred in the right parietal parasagittal region of a 43-year-old woman. A total excision was carried out. Three years and 9 months later, one parasagittal and two falx tumors in close proximity recurred and were excised. The falx tumors showed the features of an anaplastic transitional meningioma with increased mitoses. The falx meningioma recurred locally and repeatedly, despite radiation therapy and chemoimmunotherapy. She died 7 years and 8 months after the onset. At autopsy, the tumor was found to have metastasized via the cerebrospinal fluid to the spinal cord and pituitary stalk. Extracranial metastases were not evident. At the fourth craniotomy, bromodeoxyuridine (BrdU) was administered intravenously to label tumor cells in the S phase of the cell cycle. The BrdU-labeled cells accounted for 9.0%; they are usually less than 1% in benign meningiomas. Meningothelial meningiomas with a high labeling index recur rapidly, even after Simpson's grade 2 removal, and treatment for a malignant meningioma should be instituted.