COMPARATIVE DNA-CYTOMETRIC AND CYTOGENETI C DETERMINATION OF PLOIDY IN CHONDROSARCOMAS AND OSTEOSARCOMAS

10 chondrosarcomas and 10 osteosarcomas were examined using cytogeneti cs and DNA-image-cytometry. Cytogenetically 6 of 10 chondrosarcomas an d 4 of 10 osteosarcomas showed hyperdiploid tumorcells. By DNA-cytomet ry in 8 of 10 chondrosarcomas and 9 of 10 osteosarcomas hyperdiploid t umorcells resp. hyperdiploid stemlines were detected. This discrepancy reflects an in-vitro-selection depending on the different entities. I n 7 aneuploid clones of chondrosarcomas the chromosomal ploidy was cal culated using the relative length of the chromosomes and compared with the DNA-ploidy of the native tumor. There was a close relation betwee n both parameters of nuclear DNA-content. The interpretation of cytoge netic results is improved using a combination of karyotypic and DNA-cy tometric examination. This is particularly important for the search fo r relations between numeric chromosomal aberrations and morphological parameters (grading).