Osteoblastic Osteosarcoma Arising beneath an Osteochondroma in an 11-Year-Old Male with Multiple Hereditary Exostoses

Figure 4

Photomicrographs showing (a) fibrocartilaginous cap (osteochondroma or exostosis-green arrow) (H&E ×20), (b) the tumor-forming osteoid in the marrow and numerous pleomorphic bizarre osteoblasts (H&E ×100), and (c) higher power showing spicules of new bone (osteoid) (blue arrow) among the osteoblasts (red arrow) (H&E ×400).

(a)

(b)

(c)