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Thymus Cancer: Symptoms 

What are the symptoms of thymus cancer?

Thymus tumors might not cause symptoms right away. In fact, many thymus tumors are found by imaging tests of the chest that are done for some other reason. 

When thymus tumors cause symptoms, it’s often due to the tumor growing large enough to press on organs or blood vessels in the middle of your chest. These are some of the possible symptoms if this happens:

  • A cough that doesn’t go away or that gets worse over time

  • Chest pain

  • Shortness of breath

  • Trouble swallowing

  • Loss of appetite or unexplained weight loss

  • Tiredness or weakness

  • Swelling in your face and arms

  • Lightheadedness or dizziness

  • Headaches

  • Muscle weakness

  • Hoarseness of voice

  • Drooping eyelids

  • Double vision

  • Anemia, which is a low red blood cell count

  • Frequent infections

Some people with thymus tumors develop paraneoplastic syndromes. These are conditions related to cancer. But they are not caused by the growth of the tumor itself. Many people with thymus tumors develop autoimmune diseases. These may be the first sign of the tumor. The most common examples include those listed below.

Myasthenia gravis

This is an autoimmune disease that can cause severe muscle weakness. The areas affected most often are your eyes, neck, throat, and chest. This can cause blurred or double vision. It can also cause you to have trouble keeping your eyes open or looking upwards. It may also lead to trouble swallowing and breathing. You may also have serious fatigue that gets worse as the day goes on. Some people with thymus tumors also have myasthenia gravis. But most people with myasthenia gravis don’t have a thymus tumor.

Red cell aplasia

In this condition, your bone marrow does not make enough red blood cells. Red blood cells carry oxygen from your lungs to other body tissues. When your body doesn't make enough red blood cells, you have a low red blood cell count. This is called anemia. Anemia may cause weakness, dizziness, shortness of breath, and fatigue. About 1 in 20 people with thymus tumors have this. 


This is when your body does not make enough infection-fighting antibodies. These are called gamma globulins. This can make you more likely to get infections. About 1 in 20 to 1 in 10 people with hypogammaglobulinemia also have thymus tumors.

When to see your healthcare provider

Many of these symptoms can be caused by other health problems. But it is important to see your healthcare provider if you have these symptoms. Only a healthcare provider can tell if you have thymus cancer or some other condition.

Medical Reviewers:

  • L Renee Watson MSN RN
  • Marianne Fraser MSN RN
  • Todd Gersten MD