Signs and Symptoms of Thymus Cancers

Not all thymus cancers (thymomas and thymic carcinomas) cause signs or symptoms. Some are found by chance during an x-ray or CT scan done for some other reason.

Other thymus cancers are found after the cancer starts to cause signs or symptoms. These may be from the tumor itself. Or they may be part of a paraneoplastic syndrome.

Many of the signs and symptoms that can be caused by thymus tumors are more likely to be caused by something else. Still, if you have any of these problems, it’s important to see a doctor so the cause can be found and treated, if needed.

Symptoms caused by a thymus tumor

The thymus is in the middle of the chest, near the airways and certain blood vessels. Tumors in the thymus can press on nearby areas, causing symptoms such as:

• Shortness of breath
• Cough, which may bring up bloody sputum
• Chest pain
• Trouble swallowing
• Loss of appetite
• Weight loss

Superior vena cava syndrome

The thymus is near the superior vena cava (SVC), the large vein that brings blood from the head and upper body to the heart. Tumors that press on the SVC can cause the blood to back up in the veins. This can lead to symptoms of superior vena cava syndrome, which can include:

• Swelling in the face, neck, upper chest, and arms sometimes with a bluish-red skin color
• Swelling of the visible veins in this part of the body
• Trouble breathing
• Headaches
• Feeling dizzy or light-headed

While SVC syndrome can develop gradually over time, sometimes it can become life-threatening. It needs to be treated right away.

Paraneoplastic syndromes

A paraneoplastic syndrome is a condition related to the cancer but that is not caused directly by the tumor mass.

Paraneoplastic syndromes are common among people with thymomas. But they are rarely seen in people with thymic carcinoma. About 30% to 50% of people with thymomas develop an autoimmune disease, where the immune system starts to attack the body itself, as a paraneoplastic syndrome. Part of the normal function of the thymus is to help keep the immune system in check, which may help explain why this happens. Paraneoplastic syndromes often improve after the thymoma is treated, though some people may still need ongoing medical management.

Myasthenia gravis

Myasthenia gravis (MG) is the most common autoimmune disease linked with thymomas.

This disease causes the immune system to make antibodies that block the chemical signals for muscles to move. This causes severe muscle weakness. People with MG get tired easily. They may have trouble climbing stairs or walking long distances.

MG can cause loss of muscle strength throughout the body, but the most noticeable symptoms may be in the muscles of the eyes, neck, and chest:

• Weak eye muscles can cause blurred or double vision and drooping eyelids.
• Weak neck muscles can lead to problems with swallowing.
• Weak chest muscles and diaphragm can cause problems breathing and shortness of breath.

The muscle weakness from MG can become severe enough to require hospitalization, and in some cases can be life-threatening. While as many as half of people with thymomas have MG, most people with MG don’t have thymomas. Many people with MG have other, noncancerous thymus conditions.

Pure red cell aplasia

Pure red cell aplasia affects the body’s ability to make new red blood. It reduces the body’s ability to make new red blood cells.

Red blood cells carry oxygen from the lungs to other tissues of the body. Reduced red blood cell production causes low red blood cell counts. This is a condition called anemia.

Symptoms of anemia can include weakness, dizziness, shortness of breath, and tiring easily.

Pure red cell aplasia occurs in about 5% to 15% of people with thymomas. But about half of people with pure red cell aplasia will be found to have a thymoma.

Hypogammaglobulinemia

Hypogammaglobulinemia is a disorder that causes the body to make low amounts of infection-fighting antibodies known as gamma globulins. Without enough antibodies, the body has trouble fighting infections.

About 5% of people with thymomas develop hypogammaglobulinemia. About 10% of people with hypogammaglobulinemia have a thymoma.

Other autoimmune diseases

Many other autoimmune diseases have been linked to thymomas. While these are linked, many people who have these autoimmune diseases do not have a thymoma. Examples include:

• Systemic lupus erythematosus (“lupus”)
• Polymyositis
• Ulcerative colitis
• Rheumatoid arthritis
• Sjogren (Sjögren) syndrome
• Sarcoidosis
• Scleroderma