Osteosarcoma, also called osteogenic sarcoma, is characterized by the production of immature bone. It is the most common type of bone cancer. The usual symptom is recurrent pain in the affected area which does not go away with rest. Most patients with osteosarcoma are males and younger than 25 years old. Most cases are only identified when the tumor has weakened the bone so much that it resulted to a fracture. Such tumors often develop around the knee or in the upper arm. The diagnostic tests for this condition include x-ray, MRI, bone scan, CT scan, and biopsy. The treatments include surgery, chemotherapy, and radiation therapy.