[Chromosome study on giant cell tumor of bone]

Chromosome study was made in 30 specimens of giant cell tumor of bone (GCT) and osteosarcoma (OS). In 15 tumors, karyotypes were satisfactorily made for chromosome analysis, including 13 GCTs, one OS and one cell-line of same. The karyotypes of all cells were recognized and described according to the international system for human cytogenetic nomenclature. Karyotype analysis showed that GCT differs from OS both in numerical chromosomal aberrations and in structural chromosomal aberrations. The number of chromosome of GCT concentrated on diploid or subdiploid, with the exception of some superdiploid, while that of OS concentrated on superdiploid or subtriploid. Terminal deletion of chromosome was the most common cytogenetic event in GCT. This resulted in telomere-to-telomere translocations and dicentric chromosomes. Eight of the thirteen successfully analyzed GCT specimens demonstrated telometric fusion or dicentric chromosomes. Superdiploid karyotype was found in six GCTs. Contrast study with DNA flow cytometry showed that the numerical aberrations were consistent with DNA content of GCT. The other structural chromosomal aberrations were ring chromosome, marker chromosome and double minute chromatin bodies etc. The correlation between the chromosome changes and prognosis in GCT has not yet been determined, because of the short term of this study. The cytogenetic changes of osteosarcoma were much more complicated. The common chromosome structural aberrations were translocation, deletion, maker chromosome and double minute chromatin bodies etc.