GLIOSIS SPECIMENS CONTAIN CLONAL CYTOGENETIC ABNORMALITIES

The relevance of sex chromosome aneusomy and trisomy 7 in neoplastic b rain tissue is controversial. For better understanding of the relative importance of these anomalies, we made a conventional cytogenetic stu dy of cells from tissue obtained from patients who underwent partial c erebral resection for a seizure disorder. Each specimen exhibited ''gl iosis,'' but none contained histologically identifiable tumor cells. S ixty-six specimens were analyzed by routine cytogenetic methods. Noncl onal abnormalities were observed in 11.6% of the cells (86% of cases) analyzed. In 11 cases, however, simple clonal karyotypes were observed . Of these cases, six involved loss of a Y chromosome and three involv ed loss of an X chromosome. Among the cases with loss of an X chromoso me, two exhibited multiple abnormal clones. One of these cases had tri somy 7 as well as trisomy 18, and another had a supernumerary psu dic( 15)(q13). The supernumerary chromosome was constitutional. One patient had possible Klinefelter syndrome. An additional case had a clonal de l(10)(q23) that may have resulted from a hereditary fragile site. We c onclude that although some of the apparently acquired clonal and noncl onal abnormalities may be due to a consistent in vitro artifact, it is probable that they are present in the brain tissue itself. Whatever t he cause, caution should be used in interpretating cytogenetic abnorma lities observed in brain tumor specimens.