There is nothing more precious than a sound and healthy body. You don't realize that unless you are deprived of it. This is the skull of a patient with a rare form of bone cancer. Just imagine the agony caused by thousands of those sharp bone protrusions piercing through the skin, nerves, flesh and even through the eyes. An osteosarcoma or osteogenic sarcoma is a cancerous tumor in a bone. Specifically, it is an aggressive malignant neoplasm that arises from primitive transformed cells of mesenchymal origin and that exhibits osteoblastic differentiation and produces malignant osteoid. Osteosarcoma is the most common histological form of primary bone cancer. It is most prevalent in teenagers and young adults. Many patients first complain of pain that may be worse at night, may be intermittent and of varying intensity and may have been occurring for some time. Teenagers who are active in sports often complain of pain in the lower femur, or immediately below the knee. If the tumor is large, it can present as overt localised swelling. Sometimes a sudden fracture is the first symptom, because affected bone is not as strong as normal bone and may fracture abnormally with minor trauma.