DNA ploidy alterations detected during dedifferentiation of periosteal chondrosarcoma

DNA ploidy of a case with dedifferentiated periosteal chondrosarcoma was analyzed by DNA cytofluorometry. The diagnosis of primary periosteal chondrosarcoma was made on the basis of the radiographic and histological findings. At 4 years after marginal resection, the tumor recurred locally and metastasized to various organs. The patient died of disease 2 years later. Histologically, there were two components, chondrosarcoma and malignant fibrous histiocytoma, in the recurrent and metastatic tumors. DNA ploidy analysis of multiple samples revealed that the primary lesion was composed of many diploid cells with some tetraploid and octaploid cells, whereas in the dedifferentiated area, there were many aneuploid cells which were not recognized in any area of the primary tumors. This case illustrated that DNA ploidy alteration of euploidy to aneuploidy is closely correlated with the process of dedifferentiation in chondrosarcoma.