Thymoma and thymic carcinoma are diseases in which malignant (cancer) cells form in the thymus.

Thymoma and thymic carcinoma are two types of cancer that can form in the cells that cover the outside surface of the thymus. The thymus is a small organ in the upper chest under the breastbone. It is part of the lymph system and makes white blood cells, called lymphocytes, that help fight infection. These cancers usually form between the lungs in the front part of the chest and are often found during a chest x-ray that is done for another reason.

Anatomy of the thymus gland. The thymus gland is a small organ that lies in the upper chest under the breastbone. It makes white blood cells, called lymphocytes, which protect the body against infections.

Even though thymoma and thymic carcinoma form in the same type of cell, they act differently:

• Thymoma. The cancer cells look a lot like the normal cells of the thymus, grow slowly, and rarely spread beyond the thymus. A thymoma may become a thymic carcinoma over time.
• Thymic carcinoma. The cancer cells do not look like the normal cells of the thymus, grow more quickly, and are more likely to spread to other parts of the body.

Other types of tumors, such as lymphoma or germ cell tumors, may form in the thymus, but they are not considered to be thymoma or thymic carcinoma.

Signs and symptoms of thymoma and thymic carcinoma include coughing and trouble breathing.

These and other signs and symptoms may be caused by thymoma and thymic carcinoma or by other conditions.

Check with your child's doctor if your child has any of the following:

• Coughing.
• Trouble breathing.
• Pain or a tight feeling in the chest.
• Trouble swallowing.
• Hoarseness.
• Fever.
• Weight loss.
• Superior vena cava syndrome.

Children with thymoma or thymic carcinoma may also have other health problems.

Children who have thymoma or thymic carcinoma may also have one of the following immune system diseases or hormone disorders:

• Myasthenia gravis.
• Pure red cell aplasia.
• Hypogammaglobulinemia.
• Nephrotic syndrome.
• Scleroderma.
• Dermatomyositis.
• Lupus.
• Rheumatoid arthritis.
• Thyroiditis.
• Hyperthyroidism.
• Addison disease.
• Panhypopituitarism.

Tests that examine the thymus and chest are used to help diagnose thymoma and thymic carcinoma.

The following tests and procedures may be used:

• Physical exam and health history: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits and past illnesses and treatments will also be taken.
• Chest x-ray: An x-ray of the organs and bones inside the chest. An x-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body.
• CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.
• MRI (magnetic resonance imaging): A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the body. This procedure is also called nuclear magnetic resonance imaging (NMRI).
• PET scan (positron emission tomography scan): A procedure to find malignant tumor cells in the body. A small amount of radioactive glucose (sugar) is injected into a vein. The PET scanner rotates around the body and makes a picture of where glucose is being used in the body. Malignant tumor cells show up brighter in the picture because they are more active and take up more glucose than normal cells do.

  

  Positron emission tomography (PET) scan. The child lies on a table that slides through the PET scanner. The head rest and white strap help the child lie still. A small amount of radioactive glucose (sugar) is injected into the child's vein, and a scanner makes a picture of where the glucose is being used in the body. Cancer cells show up brighter in the picture because they take up more glucose than normal cells do.

• Biopsy: The removal of cells or tissues so they can be viewed under a microscope by a pathologist to check for signs of cancer.

Certain factors affect prognosis (chance of recovery).

The prognosis depends on the following:

• Whether the cancer is thymoma or thymic carcinoma.
• Whether the cancer has spread to nearby areas or other parts of the body.
• Whether the cancer was completely removed by surgery.
• Whether the cancer is newly diagnosed or has recurred (come back) after treatment.

The prognosis is better when the cancer has not spread to other parts of the body. Childhood thymoma is usually diagnosed before the tumor has spread.

After thymoma or thymic carcinoma has been diagnosed, tests are done to find out if cancer cells have spread to nearby areas or to other parts of the body.

The process used to find out if thymoma or thymic carcinoma has spread from the thymus to nearby areas or other parts of the body is called staging. Thymoma and thymic carcinoma may spread to the lungs, liver, kidneys, or the lining around the lungs and heart. The results of tests and procedures done to diagnose thymoma or thymic carcinoma are used to help make decisions about treatment.

Sometimes childhood thymoma or thymic carcinoma recurs (comes back) after treatment.

There are three ways that cancer spreads in the body.

Cancer can spread through tissue, the lymph system, and the blood:

• Tissue. The cancer spreads from where it began by growing into nearby areas.
• Lymph system. The cancer spreads from where it began by getting into the lymph system. The cancer travels through the lymph vessels to other parts of the body.
• Blood. The cancer spreads from where it began by getting into the blood. The cancer travels through the blood vessels to other parts of the body.

Cancer may spread from where it began to other parts of the body.

When cancer spreads to another part of the body, it is called metastasis. Cancer cells break away from where they began (the primary tumor) and travel through the lymph system or blood.

• Lymph system. The cancer gets into the lymph system, travels through the lymph vessels, and forms a tumor (metastatic tumor) in another part of the body.
• Blood. The cancer gets into the blood, travels through the blood vessels, and forms a tumor (metastatic tumor) in another part of the body.

The metastatic tumor is the same type of cancer as the primary tumor. For example, if thymic carcinoma spreads to the lung, the cancer cells in the lung are actually thymic carcinoma cells. The disease is metastatic thymic carcinoma, not lung cancer.

There are different types of treatment for children with thymoma or thymic carcinoma.

Some treatments are standard (the currently used treatment), and some are being tested in clinical trials. A treatment clinical trial is a research study meant to help improve current treatments or obtain information on new treatments for patients with cancer. When clinical trials show that a new treatment is better than the standard treatment, the new treatment may become the standard treatment.

Because cancer in children is rare, taking part in a clinical trial should be considered. Some clinical trials are open only to patients who have not started treatment.

Children with thymoma or thymic carcinoma should have their treatment planned by a team of doctors who are experts in treating childhood cancer.

Treatment will be overseen by a pediatric oncologist, a doctor who specializes in treating children with cancer. The pediatric oncologist works with other pediatric health professionals who are experts in treating children with cancer and who specialize in certain areas of medicine. This may include the following specialists and others:

• Pediatrician.
• Pediatric surgeon.
• Radiation oncologist.
• Pathologist.
• Pediatric nurse specialist.
• Social worker.
• Rehabilitation specialist.
• Psychologist.
• Child-life specialist.

Five types of standard treatment are used:

New types of treatment are being tested in clinical trials.

Information about clinical trials is available from the NCI website.

Treatment of thymoma and thymic carcinoma may cause side effects.

To learn more about side effects that begin during treatment for cancer, visit Side Effects.

Side effects from cancer treatment that begin after treatment and continue for months or years are called late effects. Late effects of cancer treatment may include:

• Physical problems.
• Changes in mood, feelings, thinking, learning, or memory.
• Second cancers (new types of cancer) or other conditions.

Some late effects may be treated or controlled. It is important to talk with your child's doctors about the possible late effects caused by some treatments. See the PDQ summary on Late Effects of Treatment for Childhood Cancer for more information.

Patients may want to think about taking part in a clinical trial.

For some patients, taking part in a clinical trial may be the best treatment choice. Clinical trials are part of the cancer research process. Clinical trials are done to find out if new cancer treatments are safe and effective or better than the standard treatment.

Many of today's standard treatments for cancer are based on earlier clinical trials. Patients who take part in a clinical trial may receive the standard treatment or be among the first to receive a new treatment.

Patients who take part in clinical trials also help improve the way cancer will be treated in the future. Even when clinical trials do not lead to effective new treatments, they often answer important questions and help move research forward.

Patients can enter clinical trials before, during, or after starting their cancer treatment.

Some clinical trials only include patients who have not yet received treatment. Other trials test treatments for patients whose cancer has not gotten better. There are also clinical trials that test new ways to stop cancer from recurring (coming back) or reduce the side effects of cancer treatment.

Clinical trials are taking place in many parts of the country. Information about clinical trials supported by NCI can be found on NCI’s clinical trials search webpage. Clinical trials supported by other organizations can be found on the ClinicalTrials.gov website.

Follow-up tests may be needed.

As your child goes through treatment, they will have follow-up tests or check-ups. Some tests that were done to diagnose or stage the cancer may be repeated to see how well the treatment is working. Decisions about whether to continue, change, or stop treatment may be based on the results of these tests.

Some of the tests will continue to be done from time to time after treatment has ended. The results of these tests can show if your child's condition has changed or if the cancer has recurred (come back).

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