Dedifferentiated peripheral chondrosarcoma: a review of radiologic characteristics

Introduction. Peripheral de-differentiated chondrosarcomas are among the rarest malignant mesenchymal tumors. This tumor's descriptive radiographic characteristics are reported but objective quantification does not exist. This investigation surveyed imaging of peripheral de-differentiated chondrosarcomas to facilitate better recognition of these uncommon tumors. Methods. Database interrogation for peripheral de-differentiated chondrosarcomas was performed; 23 patients were identified and imaging for 18 was reviewed. A musculoskeletal radiologist reviewed all studies for mineralization characteristics; presence of pre-existing osteochondromas; preserved corticomedullary continuity; adjacent cortical obliteration; soft-tissue mass; tumor necrosis; and presence of a cartilage cap. Tumor luminance was measured with computer software. Results. Mineralization was present in 17 tumors. Pre-existing exostoses were evident in nine cases, corticomedullary continuity was preserved in three cases. There was no difference in mineralization or other characteristics based on tumor location. Mean tumor luminance was 94.9 candela/m(2). Conclusions. The imaging characteristics described for central de-differentiated chondrosarcomas are similar to the peripheral form of this tumor. Peripheral mineralization with a bimorphic pattern on CT scan and the presence of a soft-tissue mass should be considered worrisome for a peripheral de-differentiated chondrosarcoma, particularly in the setting of multiple hereditary exostoses.