CYTOGENETIC FINDINGS IN 19 MALIGNANT BONE TURNERS

Background. The majority of karyotypes observed in osteosarcomas (OS) and chondrosarcomas (CS) are complex. Specific chromosomal abnormaliti es have not yet been characterized in either tumor except for a ring c hromosome in parosteal OS. The purpose of this study was to determine recurrent chromosomal abnormalities and establish a possible correlati on between the cytogenetic changes and the pathologic findings. Method s. Ten OS and nine CS were cytogenetically analyzed. Tumor samples wer e obtained from patients having a resection or incisional biopsy. Cyto genetic study of short term cell cultures included harvesting and G-ba nding, which were performed by routine methodologies. Results. Clonal abnormalities were observed in six OS and six CS. Modal chromosome num bers ranged from near diploid to near tetraploid in both types of tumo rs. The structural rearrangements observed in OS involved mostly chrom osomes 1, 2, 6, 12, and 17. Nonreciprocal translocations were the most frequent event. Two OS had a single clonal abnormality involving 11p1 5 and 14q32, respectively. Double minute chromosomes were observed in three cases. In CS, the most frequent structural abnormalities were no nreciprocal translocations and deletions involving numerous chromosome s. Rearrangements of Ip together with other abnormalities were observe d in four CS. Conclusions. The karyotypes were usually complex consist ing of numerical and structural changes, particularly in high grade tu mors. Rearrangements of 11p15 and 14q32 in OS and possibly Ip in CS we re found as primary cytogenetic aberrations. Cytogenetic analysis in m ore cases of OS and CS together with molecular studies are necessary t o characterize further the consistent genetic changes in these tumors.