Osteogenic sarcoma is a bone tumor in which the malignant cells are capable of directly making osteoid and or bone.
After multiple myeloma, the osteogenic sarcoma is the most common tumor of the bones.
The tumors most commonly arise in the absence of any predisposing condition.
Primary tumors are most common below the age of 20 and occur in the metaphyseal regions of the long bones before the epiphyses is closed.
Secondary osteogenic sarcomas occur in the presence of a pre-existing condition in older individuals in both long bones as well as flat bones. The pre-existing condition may be Paget's disease, fibrous dysplasia, enchondromas, exostoses, osteomyelitis, bone infarct, bone fracture or previous irradiation. Patients with familial retinoblastoma, who have a hereditary mutation on the Rb suppressor gene on chromosome 13, are at risk of developing osteogenic sarcoma usually in an irradiated area of the bone. The sporadic cases of the osteogenic sarcoma (Li-Fraumeni syndrome) are associated with mutation in p53 suppressor gene on chromosome 17.
Clinically, these tumors present with local swelling, tenderness or bone pain.
These tumors metastasize widely to the lung, other organs and bones. Lymphatic metastasis is rare.
The osteogenic sarcoma of the jaw, low grade osteogenic sarcomas, parosteal (juxtacortical) variants and intraosseous low grade osteognic sarcomas have a better prognosis than the classic osteogenic sarcomas.
Grossly, osteogenic sarcomas appear as gray-white tumors showing areas of hemorrahge and necrosis which arise in the medullary cavity of the metaphyseal ends of the long bones (proximal tibia, distal femur, proximal humerus; see figure) and locally destroy adjacent bone and may extend to the soft tissue. These tumors may lead to the destruction of the cortical bone and elevation of the periosteum (Codman's triangle). These tumors rarely destroy the epiphyseal plate.
Microscopically, the tumor cells are embedded within osteoid and/or bone. Some tumors are largely fibroblastic, some are mostly osteoblastic, some are chondroid and some are telangiectatic.