Signs and Symptoms of Thymus Cancers

Not all thymus cancers (thymomas and thymic carcinomas) cause signs or symptoms when they are found. Some are found when an imaging test of the chest (such as an x-ray or CT scan) is done for some other reason, before a person has symptoms.

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 (see below).

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 the 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 structures, 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, and upper chest, 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, and 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.

About half of people with thymomas develop paraneoplastic autoimmune diseases, where the immune system starts to attack the body itself. Part of the normal function of the thymus is to help keep the immune system in check, which may help explain why this happens.

Myasthenia gravis

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

In this disease, the immune system makes antibodies that block the chemical signals for muscles to move. This causes severe muscle weakness. People with MG tire easily. They may notice problems climbing stairs or walking long distances.

Although people with MG can lose muscle strength throughout the body, symptoms caused by weakness of the muscles of the eyes, neck, and chest may be the most troublesome:

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

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 abnormalities of the thymus.

Pure red cell aplasia

In pure red cell aplasia, the body’s ability to make new red blood cells is severely reduced.

Red blood cells carry oxygen from the lungs to other tissues of the body. Reduced red blood cell production causes anemia (low red blood cell counts).

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 in which the body makes low amounts of infection-fighting antibodies (also known as gamma globulins). This leaves the person susceptible to 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 also been linked to thymomas, but these are much less common in people with these tumors. Some examples include:

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

Most people who have these autoimmune diseases do not have a thymoma.