Fig. 2

Histologic sections of the tumor: A, B HE-stained section: microscopically, there are many polyhedral tumor cells and abundant osteoid. The eosinophilic osteoid matrix could be found intimately admixed with the highly atypical tumor cells, presenting focal deposition (A original magnification × 100; B original magnification × 400). C Immunohistochemical staining reveals the tumor cells is positive for SATB2 (original magnification × 200). D Immunohistochemical staining reveals the Ki-67 positive rate is about 60% (original magnification × 200)