Dedifferentiated chondrosarcoma is a highly malignant variant of
chondrosarcoma. Approximately 11 per cent of chondrosarcomas can be
expected to dedifferentiate into more anaplastic lesions. In this report,
we analyze the clinicopathological features and treatment of seventy-eight
lesions of this type. The ages of the patients ranged from nineteen to
eighty-two years (average, 54.6 years). The cartilaginous precursor was
central in most patients. Eleven of the lesions developed in the site of a
previously resected low-grade chondrosarcoma. Dedifferentiation was from
low-grade chondrosarcoma to osteosarcoma in forty-two patients, to
fibrosarcoma in thirty-three, and to malignant (fibrous) histiocytoma in
three. Perforation of the cortex and a soft-tissue mass were found in most
of the patients. Widespread metastatic disease within two years after
resection was a frequent finding. The over-all five-year-survival rate was
10.5 per cent. Any potential for a "cure" is related to early diagnosis and
adequate surgical treatment by amputation or resection.