Karyotypic evolution of human meningioma. Progression through malignancy.

Cytogenetic analysis of an untreated sarcomatous meningioma from a patient submitted to two surgeries separated by 1 year are reported. The material from the first surgery was mostly hypodiploid, with a modal chromosome number of 42. Alterations of chromosome 22 were found in 80.6% of the cells. Four chromosome markers were found involving chromosomes 1, 2, 6, and 22, and numerical alterations involving chromosomes 8, 9, 10, 13, 14, 15, 18, 19, 20, 21, and Y. Although the modal chromosome number of the material from the second surgery was 45 (17.9% of the cells), 43.1% of its cells were hyperdiploid, 73% of these being in the triploid-tetraploid range. Dicentric and ring chromosomes were very frequent. Alterations involving chromosome 22 were still present. There was a recurrent trisomy of chromosome 3. To our knowledge, this is the first cytogenetic description, with banding techniques, of a malignant meningioma.