Dedifferentiated Chondrosarcoma

The term dedifferentiated chondrosarcoma has been applied to tumors in which a well differentiated cartilaginous component, sometimes of demonstrably long duration, is associated with a less differentiated non-cartilaginous component that is assumed to be of relatively recent development3’2. The less differentiated component usually has the histological features of fibrosarcoma or malignant fibrous histiocytoma, although other types of malignant tumor, such as osteosarcoma or rhabdomyosarcoma, have been reported’#{176}”7. The term dedifferentiated chondrosarcoma implies that the non-cartilaginous component develops from a cartilaginous precursor, although it has been suggested that it may arise from fibrous tissue surrounding areas of necrotic cartilage’6 or from undifferentiated stem cells’7. Patients who have dedifferentiated chondrosarcoma, in contrast to most other chondrosarcomas, have a very poor prognosis; few patients survive one year after clinical presentation lO#{149} In this paper, we report a case of a patient who had dedifferentiated chondrosarcoma in which the non-cartilaginous component, ultimately recognized as malignant fibrous histiocytoma, showed a close histological resemblance to a giant-cell tumor.