What Is the Thymus Gland Responsible For?

The thymus is a gland in the upper rib cage responsible for maturing the immune system through developing a type of infection-fighting white blood cell. This gland falls into disuse and shrinks after puberty, once the immune cells have matured and traveled to lymph nodes.

The thymus is a small organ located just behind the breast bone, in the space in the chest between the lungs, in front of and above the heart. The thymus is part of the body’s immune system, but it is only active until puberty. After puberty it decreases in size and is replaced by body fat. Adults essentially live without a functioning thymus gland.  

The thymus gland is responsible for immune function. It is primarily involved in the production and maturation of a type of white blood cell called T lymphocytes (T cells). T cells develop in the thymus and travel to lymph nodes where they help the immune system protect the body from foreign invaders such as viruses, bacteria, fungus, and other types of infections.

The T lymphocytes produced by the thymus gland also help protect the body from itself by controlling cancerous cells. 

Many people with thymus diseases and thymus cancer have no symptoms. 

Symptoms of thymus problems depend on the cause and may include: 

• Reduced resistance to infectious diseases
• Muscle fatigue
• Drooping eyelids
• Shortness of breath
• Difficulty breathing
• Cough (with bloody sputum)
• Difficulty swallowing
• Headache
• Dizziness
• Weight loss
• Loss of appetite
• Chest pain
• Head, face, or neck swelling
• Bluish skin color 

Causes of thymus diseases include: 

• Genetic abnormalities
• Autoimmune disorders
• Cancer

In many people with thymus cancer, tumors are found by chance on imaging tests such as chest X-rays or CT scans done for other reasons. Other tests that may be performed to diagnose thymus problems include:

• Magnetic resonance imaging (MRI)
• Positron emission tomography (PET) scan

Thymus cancer is treated with one or more of the following:  

• Surgery
  • Removal of the thymus gland, including any tumor (thymectomy)
  • Removal of as much tumor as possible (debulking), in cases where the tumor is unable to be completely removed
• Radiation therapy
  • External beam radiation therapy (EBRT)
    • Three-dimensional conformal radiation therapy (3D-CRT) 
    • Intensity-modulated radiation therapy (IMRT) 
• Chemotherapy
  • Doxorubicin (Adriamycin)
  • Cisplatin (Platinol, Platinol-AQ)
  • Carboplatin (Paraplatin)
  • Cyclophosphamide (Cytoxan)
  • Ifosfamide (Ifex)
  • Vincristine (Oncovin)
  • Etoposide (VP-16)
  • Paclitaxel (Taxol)
  • Pemetrexed (Alimta)
  • 5-fluorouracil (5-FU)
  • Gemcitabine (Gemzar)

The corticosteroid prednisone is often given with chemotherapy.