Chromosome analysis was made of brain lesions from three patients which, according to classical histopathological criteria, did not contain tumor cells. In addition to normal cells, we identified abnormal karyotypes with clonal numerical and structural chromosome alterations in at least two independently originated primary cultures from each lesion. Our data suggest that chromosomal aberrations can exist in vivo in non-neoplastic lesions. Other abnormalities may be due to genetic instability manifested only in vitro (culture artifacts) or may already have been present in brain tissue, reflecting previous chromosome damage (as a result of exposure to chemical treatment or enviromental clastogens).
