We report for the first time on the cytogenetics of a radiation-induce
d meningioma, in a patient without neurofibromatosis. Chromosome 22 mo
nosomy was found in more than 50% of the cells examined These findings
seem to suggest that the same kind of chromosomal aberrations are fou
nd in both '' idiopathic'' and radiation-induced meningiomas and that
a common etiopathogenetic mechanism might be at work in meningiomas of
whatever origin.