Osteosarcoma Orthopaedia

Description: Osteosarcoma, also referred to as osteogenic sarcoma is a malignant osteoid producing tumor that involves the skeletal system. The abnormal cell is the malignant osteoblast. The cells are spindle shaped cells with variable amounts of pleomorphism, cytologic atypia and mitotic activity. Osteogenic sarcoma has mutlple variants that exist, including low grade intramudulary, telangetactic, chondroblastic, small blue cell. It also exists as a surface lesion, known as juxtacortical osteosarcoma. Like the intramedulary form, the surface form can be low grade, intermediate or high grade. Ninety percent of all osteosarcomas are of the conventional high grade intramedullary type.
Osteosarcoma has a strong genetic association with defects in the retinoblastoma (RB) gene. The majority of tumors will show evidence of a loss of function mutation in this gene. Patients with RB gene defects are at very high risk of developing osteosarcoma. P53, another tumor suppressor gene, like the RB is also frequently found to have loss of function in osteosarcoma cells.
Osteosarcoma is the most common primary bone malignancy comprising 22% of all malignant primary bone tumors (Mirra, 1989). There are approximately 900 new cases of osteosarcoma reported each year in the united states (American Cancer Society (ACS), 2007). This is in comparison to 180,000 new cases of breast cancer each year in the United States (ACS, 2007).