A thymoma is a tumor in the thymus gland. It is a rare, typically nonaggressive cancer that is occasionally found among people who have the autoimmune disease myasthenia gravis. Tumors typically grow slowly, but can break out of their capsules and grow aggressively. The causes of thymoma are unknown.


  • Persistent cough
  • Shortness of breath
  • Pain or pressure in the chest
  • Muscle weakness
  • Drooping eyelids
  • Double vision
  • Arm or facial swelling
  • Difficulty swallowing
  • Anemia (low red blood cell count)
  • Frequent infections
  • Fatigue
  • Dizziness

Diagnosing Thymoma

About half of the people who have a thymoma experience no symptoms at all. Often, tumors are discovered during an X-ray or CT scan performed for another reason.

Because a growing thymoma can apply pressure on other structures in the chest, many people go to the emergency room complaining of chest pressure.

A diagnosis can typically be made from a CT scan. A biopsy (tissue sample) may be needed to stage larger tumors, which, if found to be cancerous, may require chemotherapy before surgery.


The treatment plan depends on the size, location and aggressiveness of the cancer. If a tumor is cancerous, radiation and chemotherapy may be recommended. There are several types of surgeries available. 

  • Thymectomy is the removal of the thymus gland, typically done to remove a thymoma. Various surgical approaches to thymectomy exist.
  • Sternotomy involves splitting the breastbone to gain access to the thymus. This may be performed if the tumor is very large, aggressive and malignant.
  • Thoracoscopy or video-assisted thorascopic surgery (VATS) is a minimally invasive technique that involves inserting instruments and cameras through two to four small incisions made on one or both sides of the chest.
  • Robotic thymectomy is a newer minimally invasive technique that gives surgeons better visibility and greater precision in removing the thymus. Benefits might include less pain, shorter hospital stay and faster recovery.