Osteosarcoma

Osteosarcoma is the most common primary, malignant tumor of bone. The cancerous cells derive and from mesenchymal cells and are noted for their production of bone matrix. Osteosarcomas are associated with mutations in the retinoblastoma gene (RB) and p53. In the image, note the extensive, lace-like bone laid down by the cancerous cells. The cancerous cells vary in size and often contain very large nuclei.