Cytogenetic and spectral karyotype analyses of benign and malignant cartilage tumours.

To date, there have been few studies published on benign and malignant cartilage tumours using high resolution molecular cytogenetic techniques such as spectral karyotyping (SKY). In this study we have used a combination of chromosome banding, SKY and FISH to characterize the chromosomal pattern in 18 benign and malignant cartilage tumours and one small cell osteosarcoma with mesenchymal chondrosarcoma-like features. Clonal structural and/or numerical aberrations were detected in 14 of these tumours. All chondroblastomas and the chondromyxoid fibroma had diploid or near-diploid karyotypes with often relatively simple karyotypes. Although no consistent abnormalities were detected in the chondroblastomas, recurrent breakpoints were found at 2q35, 3q21-23, and 18q21. The chondromyxoid fibroma had an inv(6)(p25q13) as the sole anomaly, suggesting that this is a primary abnormality characteristic of this entity. The karyotypic findings in the chondrosarcomas were, as a rule, more complex than those in the benign tumours. A typical feature was the frequent occurrence of unbalanced rearrangements leading to genomic imbalances with losses and gains of certain chromosomes or chromosome regions. The following breakpoints were recurrent: Xq21, 6p10, 9p13, 20p11 and 22q11-12. Despite the use of high-resolution molecular cytogenetic techniques, we were not able to identify any consistent abnormalities in chondrosarcomas, suggesting that tumour-specific chromosome changes are not likely to be found in this group of tumours.