Background: Dedifferentiated chondrosarcomas consist of two distinguishable components: low-grade chondrosarcoma components and high-grade dedifferentiated components.
Materials and methods: Nine cases (4 males, 5 females) of dedifferentiated chondrosarcoma were treated in our institute. The average age was 58.6 (range, 37-86) years. The tumor location was the long bone in 7 cases (femur, n=5; humerus, n=1; tibia, n=1) and the pelvic bone in 2 cases. The average time from appearance of symptoms to treatment was 9.4 (range, 1-40) months.
Results and discussion: On plain radiographs, matrix mineralization was seen in all 9 cases (100%). Bone destruction was observed in 5 of 9 cases (56%), while pathological fracture was seen in one femur case (11%). Lung metastasis was observed in all cases (initially in 5 cases; during the treatment course in 4 cases). Surgery was performed in 8 cases, with local recurrence occurring in 2 of those cases (time to recurrence, 2 and 10 months). Chemotherapy was administered in 4 cases, but did not result in significant improvement. All 9 cases died of lung metastases, with a median survival time of 10 (range, 3.4-18.8) months. The presence of initial metastasis at diagnosis was a significant unfavorable prognostic factor.
Conclusion: The prognosis of dedifferentiated chondrosarcoma is dismal. With the lack of convincing evidence of the benefit of chemotherapy, complete surgical excision is the initial recommended treatment.