Bone cancer. Light micrograph of a section through a chondrosarcoma, a cancerous bone tumour. The cancer cells (centre) have enlarged, irregular nuclei. Chondrosarcoma may occur spontaneously in children, although this is rare. More commonly, it is a development of existing benign growths (such as chondromas) in older people. It usually causes pain and swelling. It is treated by surgical removal of the tumour, with a limited role for radiation or drug therapy. Magnification unknown.