Thymoma and thymic carcinomas are a type of cancer that affects the thymus, an organ located in between the lungs and is part of the lymphatic and immune systems. The thymus is where T-cells mature before they travel to the lymph nodes all over the body. These T-cells are very important to the body’s ability to adapt to and fight off new illnesses from bacteria, viruses and fungal infections.

The thymus reaches full maturity during puberty. After this stage, the organ slowly begins to be replaced by fatty tissue as the patient ages.

In the past, thymoma was considered by the medical community to have the ability to be either benign (noncancerous) or malignant (cancerous). However, thymoma is now considered to be always possibility malignant and the best way to determine if the condition will recur after treatment is to examine if the tumors have spread to other areas.

See also emphysema, mediastinal tumors, mesothelioma and sarcoidosis for other lung diseases.


Symptoms of thymoma and thymic carcinoma will vary from patient to patient depending on the severity of the condition and whether the tumor has spread to other areas of the body. In the early stages of the condition, patients may not notice any symptoms at all. When symptoms are present, they may include:

  • Shortness of breath
  • Cough, which may contain blood
  • Chest pain
  • Trouble swallowing
  • Loss of appetite
  • Weight loss

If the tumor is affecting the main blood vessel between the head and heart, known as superior vena cava, superior vena cava syndrome may develop. Symptoms of this syndrome can include:

  • Swelling in the face, neck, and upper chest, sometimes with a bluish color
  • Swelling of the visible veins in this part of the body
  • Headaches
  • Feeling dizzy or lightheaded

Thymoma and thymic carcinoma can cause secondary conditions that develop because of the tumor. These secondary conditions often include autoimmune disorders that cause the body to attack itself, such as myasthenia gravis, red cell aplasia, hypogammaglobulinemia and other autoimmune disorders. Symptoms of these autoimmune disorders may also be present.

Causes and Risk Factors

In the United States, thymoma is most commonly diagnosed in Asian and Pacific Islander communities. The risk of developing this condition increases with age and most patients are in their 70s when they are diagnosed.


Diagnosis of thymoma and thymic carcinoma can happen unintentionally when a patient has a chest x-ray or CT scan performed for another reason.

When this does not happen, the patient may visits their physician because they are experiencing symptoms and be diagnosed at that time. Diagnosis of the condition usually begins with a physical exam and a review of the patient’s medical history and symptoms. The only way to positively diagnose thymoma is through a biopsy of the affected tissue. Other diagnostic tests may be performed in order to better understand the condition.

A biopsy of the affected tissue is the only way to positively diagnose thymoma. During a biopsy, a sample of tissue may be removed either by using a needle or during a surgical procedure. This tissue is then examined under a microscope to determine if cancer is present.

Chest x-rays, CT scans, magnetic resonance imaging (MRI) or positron emission tomography (PET) may be used to provide an image of what is going on inside the body and are often used to make an initial diagnosis and better understand the patient’s condition. If these imaging tests suggest the presence of thymoma or other cancers, a biopsy is performed.

Blood tests to check for markers that indicate if cancer or an autoimmune disorder is present may also be performed.


Treatment of thymoma and thymic carcinoma will depend on the stage of the condition and whether it has spread to other areas. Most treatments will involve surgery, radiation therapy, chemotherapy or a combination of one or more of these treatments.

When the tumor is able to be completely removed during surgery, this is generally the best treatment option. For early stages of thymoma this is often the only treatment needed. When the cancer has progressed to a later stage, surgery may be used to remove as much of the tumor as possible.

Radiation therapy is used after surgery when the thymoma is at a later stage and unable to be fully removed during surgery. The radiation therapy directs an x-ray beam at the tumor in order to destroy the cancer cells. This can also help shrink the tumor before surgery is performed.

Chemotherapy uses a mixture of medications that work to kill off the cancer cells. These medications can also damage or destroy healthy cells during treatment; however, most side effects go away after the treatment is completed. Chemotherapy is generally used for patients with Stage IVB thymoma, which is unable to be completely removed during surgery or if the cancer continues to return.

Early treatment can help achieve a better outcome. Because this condition is rare and can be difficult to diagnose, it is important for patients to seek medical attention from a specialist who is familiar with thymoma. The knowledgeable and highly trained staff at the Women's Guild Lung Institute work as a multidisciplinary team to determine the best treatment option for each patient.

© 2000-2022 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.
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