Imaging differentiation of central grade I chondrosarcoma from enchondroma in long bones

Objective: To evaluate imaging features for in differentiating central grade I chondrosarcoma from enchondroma in long bones. Methods: Images of 32 patients with central grade I chondrosarcoma (n = 18) and enchondroma in long bones (b-14) confirmed by surgery and postoperative 5 years follow up were retrospectively reviewed. All patients underwent X-ray, enhanced and non-enhanced MRI. Imaging features were independently assessed. The Chi-square test was used to identify features with differentiating strength. Results: (1) X-ray: all tumors documented multiple patchy and cluster ossifications located in the central regions of marrow cavities, and there was no sclerified edges around the tumors. Osteolysis were not seen within or around the lesions. It was difficult to estimate the extent of tumors because there was no definite boundary. (2) MR: there was no hemorrhage, ossification and margin enhancement seen in all cases. Of the 18 central grade I chondrosarcomas, 16 was located in diaphysis/metaphysis of the extremities, 15 had cortical bony destruction, 13 had abnormal signal around bone marrow. Of the 14 enchondroma in long bone, 8 was located in diaphysis/metaphysis of the extremities, 1 had cortical bony destruction, 4 had abnormal signal around bone marrow. No statistically significant difference was found between central grade I chondrosarcoma and enchondroma in long bones, (χ² values were 4.233, 18.286, 6.026, P < 0.05). Soft masses were only seen in central grade I chondrosarcomas. Conclusion: Location in diaphysis/metaphysis of the extremities, cortical destruction, soft mass, and abnormal signal around marrow are the most reliable predictors for differentiating central grade I chondrosarcoma from enchondroma in long bones. (authors)