Osteosarcoma is the most common type of malignant bone cancer, accounting for 35% of primary bone malignancies. There is a preference for the metaphyseal region of tubular long bones. 50% of cases occur around the knee. It is a malignant connective (soft) tissue tumor whose neoplastic cells present osteoblastic differentiation and form tumoral bone.
Family physicians and orthopedists rarely see a malignant bone tumor (most bone tumors are benign). Thus, many patients are initially misdiagnosed with cysts or muscle problems, and some are sent straight to physical therapy without an x-ray.
The route to osteosarcoma diagnosis usually begins with an x-ray, continues with a combination of scans (CT scan, PET scan, bone scan, MRI) and ends with a surgical biopsy. Films are suggestive, but bone biopsy is the only definitive method to determine whether a tumor is malignant or benign.
The biopsy of suspected osteosarcoma should be performed by a qualified orthopedic oncologist. The American Cancer Society states: “Probably in no other cancer is it as important to perform this procedure properly. An improperly performed biopsy may make it difficult to save the affected limb from amputation.”