Symptoms & Signs of Thymus Cancer

April 11, 2026

This page was reviewed under our medical and editorial policy by Amanda Reyes, M.D., Medical Oncologist, City of Hope^® Cancer Center Duarte. 

Thymus cancer develops in the cells of the thymus gland, a small organ behind the breastbone that plays a key role in developing some of the body’s immune cells. Thymus cancer may begin in different cell types within the thymus, including the epithelial cells and the neuroendocrine cells.

Most patients with thymus cancer do not have symptoms before they are diagnosed. However, some may experience signs or symptoms of the condition. A sign of cancer is something that is something objective and measurable that may be seen or detected by a doctor or another person, such as a lump or swelling. A symptom is something that only the patient experiences, such as pain or fatigue.

The two most common types of thymus cancer begin in the epithelial cells and are referred to as thymoma and thymic carcinoma.

Thymic Carcinoma and Thymoma Symptoms

Many patients do not experience symptoms related to thymus cancer. However, among those who do, some of the more common signs and symptoms of thymoma or thymic carcinoma include:

• A cough that brings up blood
• Feeling short of breath or having chest pain
• Trouble swallowing or changes to appetite
• Unexpected weight loss
• Dizziness or light-headedness
• Hoarse voice
• Swelling in the face, neck or upper chest, which can be a sign of superior vena cava syndrome — a condition that may be the result of a tumor pushing on the vena cava veins

Related Conditions

Because thymus cancers may disrupt how the body’s immune system works, some patients may develop immune system conditions that are related to a tumor, even if the tumor does not directly cause the condition. These conditions are called paraneoplastic syndromes, listed below.

Myasthenia gravis: This is a condition where the body produces antibodies that block the signals that control certain muscles. This may lead to muscle weakness or fatigue and affects up to 30%-50% of all thymoma patients.

Pure red cell aplasia: This affects around 1 in 10 thymoma patients. It is a condition where the body does not produce enough red blood cells, leading to issues such as dizziness, fatigue or shortness of breath.

Hypogammaglobulinemia: This is a condition where the body does not produce enough gamma globulins, a type of cell that helps fight infections. Hypogammaglobulinemia affects about 5% of patients with thymoma.