Correlation between radiograph imaging and degree of chondrosarcoma histopathology

Background: Chondrosarcoma is the second most common primary bone tumor in adults after osteosarcoma. It is difficult to distinguish between low and high-grade chondrosarcoma radiographically, due to its various imaging appearances. Therefore, an imaging analysis method is needed to increase grading accuracy preoperatively. This study aim was to evaluate the correlation between imaging characteristics and degree of chondrosarcoma from histopathology.

Material and methods: This study was approved by the ethical clearance and ethics committee in our centre. A cross sectional study was conducted of 22 subjects with histopathology proven diagnosis of chondrosarcoma and had met both inclusion and exclusion criteria. Bone destruction, endosteal scalloping, transitional zone, chondroid matrix calcification, and periosteal reaction were the imaging characteristic that was re-evaluated by two radiologists with hidden identification.

Result: Mean age of all subjects was 43.22 ± 14.28 years old, with slight female predominance (54.5%). 21 out of 22 chondrosarcomas (95.55%) were found in appendicular skeleton and the most frequent site was found in iliac bone (31.82%), followed by femur, humerus, and pubic ramus. Bone destruction and soft tissue mass were the characteristics found on high-grade chondrosarcoma as many as 94% and 100% respectively, in the other hand all low-grade chondrosarcoma none has a picture of endosteal scalloping and periosteal reaction. Still, all low-grade chondrosarcoma has a chondroid matrix. Transitional zone margin 1B and 1C were discovered more on high-grade chondrosarcoma, whereas 1A, 1B, and no 1C were detected on low-grade chondrosarcoma. A radiographic abnormality score ≥3 has 4.7 times more chance to become a high degree greater than <3 score, with ROC curve 0.96 (p<0.05). The intraobserver and interobserver scores were r = 0.630.

Conclusion: Each abnormality in this plain photo cannot stand alone, but must be combined and produce a total score of radiograph abnormality. A radiograph abnormality score with cut off value 3 can help to determine chondrosarcoma’s histopathology degree. Further research with a larger sample and better image quality can be done to increase statistical analysis accuracy.