Sarcoma

Diagnostic Approaches

There are no standard screening tests for sarcoma. Instead, your doctor will likely make the diagnosis through a combination of a clinical examination, imaging tests and confirmation by a biopsy. Your doctor will recommend specific tests required to make a correct diagnosis based on your age and medical condition, inherited disorders, type of cancer suspected, severity of symptoms and previous test results.

Imaging Tests

Imaging tests can be done to look for the cause of symptoms and to find a sarcoma tumor. They may also be done after a sarcoma is diagnosed to see if it has metastasized (spread) to other parts of the body.

X-ray. An X-ray of the area with the lump is often the first imaging test done, but it is usually not the only imaging test for diagnosing sarcoma. Rather, an X-ray is done to detect any abnormalities that may be sarcoma. If the findings on an X-ray suggest sarcoma, other imaging tests will be ordered. A chest X-ray may be done after an initial diagnosis to see if it has spread to the lungs.

Ultrasound. This test involves the use of sound waves to create a picture of internal organs. An ultrasound can sometimes determine if a lump is a cyst with fluid, which is likely to be benign (noncancerous) and not a sarcoma. An ultrasound can also be used to help guide a biopsy needle precisely into a tumor inside the body.

Computed tomography (CT). A CT is often performed if the doctor suspects sarcoma in the chest or abdomen. CT is an X-ray procedure in which three-dimensional images of structures in the body are created by a computer integrated with the X-ray. The detailed, cross-sectional images of the body can show if sarcoma has spread into the lungs, liver or other organs. Sometimes a special dye (called a contrast) is injected into a vein in the arm or is taken as a pill to provide better detail on the image. CT (like an ultrasound) can also be used to help guide a biopsy needle precisely into a tumor.

Magnetic resonance imaging (MRI). MRI is routinely done if a doctor suspects sarcoma. MRI can show the location of a tumor, the size of the tumor and sometimes even the type of tissue (like fat or muscle). All of these details are helpful for planning a biopsy. With MRI, radio waves and strong magnets are used to create detailed images of organs and tissues. These images are often better than CT images for evaluating sarcomas in the arms or legs. MRI is also used to see if sarcoma is present in the brain and spinal cord.

Positron emission tomography (PET). This specialized test may be ordered to see if sarcoma has spread. PET is not often used for sarcoma, but it can be helpful in certain cases.

Sometimes, PET and CT are integrated to collect images from both types of tests. The resulting combination of images provides more information about the structure of a tumor and how much energy it uses compared with normal tissues. This information can be helpful when trying to determine if abnormalities seen on the CT image are cancer or benign tumors.

Biopsy

The most important procedure to confirm a diagnosis of sarcoma is a biopsy. A small amount of tissue from the tumor is removed, and a pathologist (a doctor trained to examine tissues and interpret the results) examines the tissue through a microscope to determine if cancer cells are present.

Several types of biopsy may be used to diagnose sarcoma. Doctors experienced with these tumors will choose one or more types of biopsy based on the size and location of the tumor. Samples are taken from the primary tumor, lymph nodes or other suspicious areas.

For a needle biopsy, a doctor inserts a hollow needle into the tumor to obtain tissue or cells for examination. Two types of needle biopsy may be done: core-needle or fine-needle. If the tumor is too deep to feel, the doctor can use CT or ultrasound to help guide the needle accurately into the tumor.

Surgical biopsies include an incisional biopsy, which almost always involves removing enough tissue to diagnose the exact type and grade of sarcoma, and an excisional biopsy, in which the surgeon removes the entire tumor.

Molecular Laboratory Testing

Your doctor may suggest molecular laboratory tests on a tumor sample to identify specific genes, proteins and other factors unique to the tumor. Sometimes these special tests are needed to accurately determine whether a sarcoma is present and, if so, what type. Your doctor may also use the test results to recommend the best treatment because certain types of sarcoma may respond to different treatments. Ask your doctor if the tissue samples from other testing can be used for molecular testing to prevent additional procedures, if possible.

 

 

Bone Sarcoma Tests

If bone sarcoma is suspected, your doctor also may recommend the following tests:

Blood tests may help find bone cancer because people with osteosarcoma or Ewing sarcoma may have higher alkaline phosphatase and lactate dehydrogenase levels in the blood. High levels, however, do not always mean cancer. Alkaline phosphatase is normally high when cells that form bone tissue are very active, such as when children are growing or a broken bone is healing.

Bone scans use a radioactive tracer to look at the inside of the bones. The tracer is injected into a vein and collects in areas of the bone. Healthy bone is detected by a special camera and appears gray. Areas of injury, such as those caused by cancerous cells, appear dark.

 

Additional Resources

 

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