DNA ploidy alterations detected during dedifferentiation of periosteal chondrosarcoma

DNA ploidy of a case with dedifferentiated periosteal chondrosarcoma was an alyzed by DNA cytofluorometry. The diagnosis of primary periosteal chondros arcoma was made on the basis of the radiographic and histological findings. At 4 years after marginal resection, the tumor recurred locally and metast asized to various organs. The patient died of disease 2 years later. Histol ogically, there were two components, chondrosarcoma and malignant fibrous h istiocytoma, in the recurrent and metastatic tumors. DNA ploidy analysis of multiple samples revealed that the primary lesion was composed of many dip loid cells with some tetraploid and octaploid cells, whereas in the dediffe rentiated area, there were many aneuploid cells which were not recognized i n any area of the primary tumors. This case illustrated that DNA ploidy alt eration of euploidy to aneuploidy is closely correlated with the process of dedifferentiation in chondrosarcoma.