Dedifferentiated central chondrosarcoma.

BACKGROUND: The prognosis for patients who develop dedifferentiation of central chondrosarcoma traditionally has been poor. Because not much has been reported about this rare lesion, many uncertainties remain about prognostic factors.

METHODS: In this retrospective study, the clinical, radiographic, and histologic features and the treatments in 123 patients from the Rizzoli Institute were reviewed in an attempt to define which factors may be related to outcome in patients with dedifferentiated central chondrosarcoma.

RESULTS: Among 123 patients who were included in this study, 109 patients were treated at the Rizzoli Institute, and 14 patients were seen in consultation. There were 66 males and 57 females, and their average age was 59 years. The femur (62 patients), pelvis (28 patients), and humerus (20 patients) were the most common locations. Radiographically, a soft tissue mass was present in 87% of patients, and a bimorphic pattern was appreciated in 53% of patients. Histologically, the cartilaginous component was considered Grade 1 in 63% of patients and Grade 2 in 37% of patients. In most patients, the dedifferentiated component showed the features of an osteosarcoma (92 patients), followed by fibrosarcoma (19 patients), and malignant fibrous histiocytoma (9 patients). For 101 patients, surgery was a component of their definitive management. In 25 patients, surgery was combined with chemotherapy. The 2-year and 5-year survival rates were 34% and 24%, respectively. The median survival was 13 months (95% confidence interval, 9-17 months).

CONCLUSIONS: Metastatic disease at diagnosis, malignant fibrous histiocytoma dedifferentiation, and a high percentage of dedifferentiated component were related to poorer outcomes. There was no statistical evidence of any beneficial effect from adjuvant chemotherapy.