Cytogenetic findings in 19 malignant bone tumors.

BACKGROUND

The majority of karyotypes observed in osteosarcomas (OS) and chondrosarcomas (CS) are complex. Specific chromosomal abnormalities have not yet been characterized in either tumor except for a ring chromosome in parosteal OS. The purpose of this study was to determine recurrent chromosomal abnormalities and establish a possible correlation between the cytogenetic changes and the pathologic findings.

METHODS

Ten OS and nine CS were cytogenetically analyzed. Tumor samples were obtained from patients having a resection or incisional biopsy. Cytogenetic study of short term cell cultures included harvesting and G-banding, which were performed by routine methodologies.

RESULTS

Clonal abnormalities were observed in six OS and six CS. Modal chromosome numbers ranged from near diploid to near tetraploid in both types of tumors. The structural rearrangements observed in OS involved mostly chromosomes 1, 2, 6, 12, and 17. Nonreciprocal translocations were the most frequent event. Two OS had a single clonal abnormality involving 11p15 and 14q32, respectively. Double minute chromosomes were observed in three cases. In CS, the most frequent structural abnormalities were nonreciprocal translocations and deletions involving numerous chromosomes. Rearrangements of 1p together with other abnormalities were observed in four CS.

CONCLUSIONS

The karyotypes were usually complex consisting of numerical and structural changes, particularly in high grade tumors. Rearrangements of 11p15 and 14q32 in OS and possibly 1p in CS were found as primary cytogenetic aberrations. Cytogenetic analysis in more cases of OS and CS together with molecular studies are necessary to characterize further the consistent genetic changes in these tumors.