Dedifferentiated chondrsarcoma: a clinicopathologic analysis of 25 cases.

Background: To investigate the clinical, imaging and pathological features of dedifferentiated chondrosarcoma for better diagnosis.

Methods: Patients who had been confirmed to have dedifferentiated chondrosarcoma were enrolled in this study and analyzed in the clinical, imaging and pathological data.

Results: Twenty-five patients had pathologically confirmed dedifferentiated chondrosarcoma including 15 males and 10 females with an age range of 24-74 (median 58, interquartile range 49-65). Ten patients had the tumor at the femur, four at the ilium, two at the humerus, two at the tibia, two at cotyle, and one at each of the following locations: scapula, sacrum, rib, pubic branch, and calcaneus. Twenty-one patients had local pain and a soft tissue mass while the other four patients had only local pain without a soft tissue mass. Four patients had pathological fractures. Imaging showed extensive bone destruction with calcification inside the lesion and possible pathological fractures. On gross observation of the specimen, the chondrosarcoma components were usually located inside the bone, and the dedifferentiated sarcoma components were mainly located outside the bone. Microscopy showed the dedifferentiated tumor had two components: well-differentiated chondrosarcoma and poorly differentiated non-chondral sarcoma including malignant fibrous histiocytoma in eleven cases, osteosarcoma in ten cases, fibrosarcoma in two, liomyosarcoma in one, and lipoblastoma in the remaining one.. Followed up from 3 moths to 60 months (mean 15.6), eight patients died with a survival time of 10-23 months (mean 16), and the other 17 patients survived with the survival duration from three to 60 months (15).

Conclusion: Dedifferentiated chondrosarcoma is a fatal disease with multiple components, and most of the cases have dual morphological and imaging features of chondrosarcoma and non-chondrosarcoma. The imaging presentations are primarily of common central chondrosarcoma, combined with cortical destruction, soft tissue mass, and pathological fractures.