Because osteosarcoma is very rare, your doctor will ask about your symptoms and check for more common causes of limb pain and swelling, such as sports injuries and arthritis. He or she will examine the painful area, feeling for warmth, swelling, and tenderness, and looking for signs of joint swelling or fluid. You'll be asked about any difficulty moving the limb or using the joint.
The true cause of your symptoms may not be known until your doctor orders an x-ray of the area. Blood tests may be ordered, too. In most cases, the blood tests will be normal, although some patients will have high levels of certain enzymes. However, the x-ray typically shows characteristic abnormalities suggesting cancer.
Once your doctor has x-ray evidence of a bone tumor, he or she will refer you to a major medical center with the facilities, staff, and experience to treat bone cancer. There, you may have a magnetic resonance imaging (MRI) scan of the area to determine how far the tumor has invaded nearby nerves, blood vessels, and joints. You also may have x-rays and a bone scan to see whether the cancer has spread to your lungs, other bones, and other parts of your body.
When these tests are complete, you will have a biopsy to confirm the diagnosis. In a biopsy, a small piece of bone is removed and checked for cancer cells in a laboratory.