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Thymus Cancer: Diagnosis

If your healthcare provider thinks you might have a thymus tumor, you will need certain exams and tests to be sure. Diagnosing a thymus tumor starts with your healthcare provider asking you questions. He or she will ask you about your health history, your symptoms, risk factors, and family history of disease. Your healthcare provider will also give you a physical exam.

What tests might I need?

You may have one or more of the following tests:

  • Imaging tests

  • Blood tests

  • Biopsy

Imaging tests

Imaging tests are used to look for a thymus tumor.

Chest X-ray

If your healthcare provider thinks you have a problem in the middle of your chest, he or she may do an X-ray. It can often show tumors in the thymus, nearby organs, or lymph nodes.  

Computed tomography (CT) scan

For this test, you lie on a table as it slides through a CT scanner. The scanner takes many X-rays. Then a computer combines these images to make pictures for your healthcare provider to look at. CT scans show much more detail than chest X-rays.

Magnetic resonance imaging (MRI)

MRIs use radio waves and magnets to create very detailed images of the inside of your body. You may have this test if you cannot have a CT scan for some reason.

Positron emission tomography (PET) scan

For this test, you’re injected with a slightly radioactive sugar. Tumor cells collect more of the sugar than normal cells. Your healthcare provider then uses a special camera to take a picture of your whole body. The images from PET scans are not as detailed as those from CT or MRI scans. But they can often show if an abnormal area is a tumor. Some machines can do a PET scan and CT scan at the same time.

Blood tests

Blood tests cannot be used to diagnose thymus tumors. But they can still sometimes be helpful. For instance, your healthcare provider may do blood tests to look for antibodies in your blood. These can sometimes be found in people with myasthenia gravis or other autoimmune disorders linked to thymus tumors.


If your healthcare provider spots a thymus tumor on an imaging test, he or she will decide if it can be removed. If it can be, the next step is often surgery to remove the tumor and the thymus. In some cases, the diagnosis is not clear or surgery cannot remove the whole tumor. When this happens, your healthcare provider may remove a sample of the tumor during a biopsy. A doctor who specializes in looking at cells, called a pathologist, then looks at the samples under a microscope.

Needle biopsy

For this test, a thin, hollow needle is put through your skin and into the tumor to get a sample of it. This is often done during a CT scan of your chest. This lets your healthcare provider see the needle going into the tumor. This is less invasive than an open (surgical) biopsy. However, it may not always collect enough of a sample to make a clear diagnosis.

Open biopsy

A biopsy may be taken during surgery. This is more invasive than a needle biopsy. But it’s also more likely to provide a large enough sample for diagnosis.

Getting your test results

When your healthcare provider has the results of your tests, he or she will contact you with the results. Your provider will talk with you about other tests you may need if a thymus tumor is found. Make sure you understand the results and what follow-up you need.

Online Medical Reviewer: Alteri, Rick, MD
Online Medical Reviewer: Gersten, Todd, MD
Last Review Date: 6/1/2016
© 2013 The StayWell Company, LLC. 780 Township Line Road, Yardley, PA 19067. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare provider's instructions.