Osteosarcoma - Childhood and Adolescence: Diagnosis

Approved by the Cancer.Net Editorial Board, 01/2022

ON THIS PAGE: You will find a list of common tests, procedures, and scans that doctors use to find the cause of a medical problem. Use the menu to see other pages.

Doctors use many tests to find, or diagnose, cancer. They also do tests to learn if cancer has spread to another part of the body from where it started. If the cancer has spread, it is called metastasis. Doctors may also do tests to learn which treatments could work best.

For most types of cancer, including osteosarcoma, a biopsy is the only sure way for the doctor to know if an area of the body has cancer. During a biopsy, the doctor takes a small sample of tissue for testing in a laboratory. It is important that the health care team members performing the biopsy are experienced with this type of tumor and would be able to remove the tumor, if needed.

How osteosarcoma is diagnosed

There are many tests used for gathering more information when a bone tumor is present. The diagnosis of osteosarcoma can only be confirmed by a biopsy. Not all tests described here will be used for every person. Your child’s doctor may consider these factors when choosing a diagnostic test:

  • The type of cancer suspected

  • Your child's signs and symptoms

  • Your child's age and general health

  • The results of earlier medical tests

In addition to a physical examination, the following tests may help in coming up with a suspected diagnosis of osteosarcoma. A health care team with experience diagnosing and treating bone tumors should perform these tests.

  • X-ray. An x-ray is a way to create a picture of the structures inside of the body using a small amount of radiation. The doctor will take an x-ray of the area where there is a lump or swelling. Osteosarcoma usually shows certain common features on an x-ray. Its appearance on an x-ray can lead to suspicion that an osteosarcoma may be present.

  • Computed tomography (CT or CAT) scan. A CT scan takes pictures of the inside of the body using x-rays taken from different angles. A computer combines these pictures into a detailed, 3-dimensional image that shows any abnormalities or tumors. A CT scan can be used to measure the tumor’s size. Sometimes, a special dye called a contrast medium is given before the scan to provide better detail on the image. This dye can be injected into a person's vein or given as a pill or liquid to swallow. In osteosarcoma, CT scans are frequently used to get images of the lungs as a potential location of tumor metastases. They can also be used at the site the tumor started at as a means of characterizing the tumor and its relationship to vital normal structures. A CT scan is frequently performed before a biopsy to ensure the biopsy is placed properly.

  • Magnetic resonance imaging (MRI). An MRI uses magnetic fields, not x-rays, to produce detailed images of the body. MRI can be used to measure the tumor’s size. A special dye called a contrast medium is given before the scan to create a clearer picture. This dye can be injected into a person's vein or given as a pill or liquid to swallow. An MRI creates an image that is based on different physical properties of the tumor as compared to CT scans. MRI is used by some doctors to find out more about the site where the tumor started. Similar to a CT scan, it can help the orthopedic oncologist plan surgery. An orthopedic oncologist is a doctor who specializes in surgery to remove tumors on the bones and soft tissues. Surgery removes the tumor-containing area of bone along with a portion of the surrounding healthy tissue, called the margin. Sometimes biopsies are performed by orthopedic oncologists or interventional radiologists, which are doctors who use image-guided procedures to diagnose and treat disease. Some oncologists prefer CT scans, some prefer MRI, and some prefer both along with x-rays to image the location where the tumor started.

  • Positron emission tomography (PET) or PET-CT scan. A PET scan is usually combined with a CT scan (see above), called a PET-CT scan. However, you may hear your doctor refer to this procedure just as a PET scan. A PET scan is a way to create pictures of organs and tissues inside the body. A small amount of a radioactive sugar substance is injected into the person's body. This sugar substance is taken up by cells that use the most energy. Because cancer tends to use energy actively, it absorbs more of the radioactive substance. However, the amount of radiation in the substance is too low to be harmful. A scanner then detects this substance to produce images of the inside of the body. In osteosarcoma, a PET scan is used to find a tumor located in other places in the body that are distant from where the tumor started. Some oncologists prefer PET scans for distant disease (along with a chest CT scan), while other doctors prefer bone scans, which are described below.

  • Bone scan. A bone scan uses a radioactive tracer to look at the inside of the bones. The amount of radiation in the tracer is too low to be harmful. The tracer is injected into a patient’s vein. It collects in areas of the bone and is detected by a special camera. Healthy bone appears lighter to the camera, and areas of injury, such as those caused by cancer, stand out on the image. A bone scan is a way to find out whether or not osteosarcoma may have spread to other bones beyond the place it started.

  • Biopsy. biopsy is the removal of a small amount of tissue for examination under a microscope. Other tests can suggest that a tumor is present, but only a biopsy can make a definitive diagnosis. A pathologist then analyzes the sample(s). A pathologist is a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease. The material obtained from the biopsy can also be used for testing genetic changes in the tumor. You should discuss this with your child's doctor, as different sites may lead them to recommend different gene tests. Some of these studies are performed as part of participation in clinical trials.

    A doctor who specializes in bone tumors should perform the biopsy. The biopsy typically involves surgery. However, sometimes the doctor may use a needle biopsy. These procedures are at times performed by orthopedic oncologists and sometimes interventional radiologists. A needle biopsy uses a hollow needle inserted into the tumor. For bone tumors, a "core needle" biopsy may be large enough to make the diagnosis. A "fine needle" aspiration is a type of biopsy used for several other cancer types that uses a very thin needle. However, it is rarely appropriate for osteosarcoma. It is critical that sufficient material is obtained during the biopsy to ensure the pathologist can make an accurate diagnosis. Osteosarcoma is most often diagnosed based on its specific characteristics and appearance under a microscope. The doctor may analyze the genes or other features of the cancer cells, most often to tell osteosarcoma apart from other types of cancer that have more characteristic genetic features.

After diagnostic tests are done, your child’s doctor will review the results with you. If the diagnosis is cancer, these results also help the doctor describe the location(s) of the cancer. This is called staging.

The next section in this guide is Stages. It explains the system doctors use to describe the extent of the disease. Use the menu to choose a different section to read in this guide.