Fig. 6

Histopathologic images a H&E staining, × 100 (case 7, grade II). The lesion showed proliferation of tumor cells within the chondroid matrix with focal calcification. b H&E staining, × 200 (case 7, grade II) Atypical chondrocytes presented with increased cellularity, pleomorphism, multinucleation, and mitoses. c S-100 protein, × 100 (case 3, grade II) immunohistochemistry showed diffuse positive expression of S-100 protein. d Ki-67, × 200 (case 4, grade II) immunohistochemistry showed 15–20% positive expression of Ki-67