Mediastinal Tumor

Mediastinal tumors include thymomas, lymphomas, germ cell tumors and cysts, among others. They’re masses of cells that appear in the space between your lungs, called the mediastinum. These tumors may be malignant (cancerous), but they’re usually benign (noncancerous). Surgery is the most common treatment.


Front view of the mediastinum and side view that includes the anterior, middle and posterior parts
Mediastinal tumors form in your mediastinum’s anterior, middle or posterior parts.

What are mediastinal tumors?

Tumors (also called neoplasms) are masses of cells. They can be benign (not cancerous) or malignant (cancerous). Mediastinal tumors are growths that form in the area of your chest between your lungs.

This area, called the mediastinum, is surrounded by your breastbone in front, your spine in back and your lungs on each side. Your mediastinum contains your heart, aorta, esophagus, thymus, thyroid, trachea, lymph nodes and nerves. Your thymus is an organ that’s part of your immune system. Your lymph system, or lymphatic system, is also part of your immune system and helps protect your body.

What are the types of mediastinal tumors?

There are several types of mediastinal tumors. They’re classified based on where they are in your mediastinum: the anterior (front), middle or posterior (back).

Anterior (front) mediastinal masses
  • Thymoma and thymic carcinoma: Thymomas are the most common mediastinal tumors. They’re cancerous tumors that start in your thymus gland. Most thymomas grow slowly. A more aggressive cancerous tumor that forms on your thymus gland, called thymic carcinoma, grows and spreads more quickly than thymomas.
  • Thymic cysts: Thymic cysts are benign. They usually only require treatment if they’re placing pressure on nearby structures and causing symptoms.
  • Lymphoma: These malignant tumors include both Hodgkin lymphoma and non-Hodgkin lymphoma.
  • Germ cell tumor: Your mediastinum is the most common place for germ cell tumors to form other than your gonads (ovaries or testicles). The majority of germ cell tumors are benign.
  • Thyroid mass: This is usually a benign growth, like a goiter.
Middle mediastinal masses
  • Bronchogenic cyst: These small, benign cysts are usually filled with fluid or mucus.
  • Mediastinal lymphadenopathy: This condition involves having swollen or enlarged lymph nodes.
  • Pericardial cyst: These benign growths form in the fluid-filled sac that surrounds your heart, called the pericardium.
  • Tracheal tumors: Tumors in your windpipe, or trachea, may be benign or malignant.
  • Esophageal tumors: Tumors in your esophagus, or food pipe, may be benign or malignant.
  • Esophageal conditions: These are benign conditions of your food pipe that include achalasia, diverticulum and hiatal hernia.
  • Blood vessel conditions: These include aortic aneurysm and aortic dissection.
Posterior (back) mediastinal masses
  • Neurogenic tumors: These tumors form in nerve tissue. They’re the most common posterior mediastinal tumors. They include nerve sheath tumors, ganglion cell tumors and paragangliomas. Most neurogenic tumors are benign.
  • Mediastinal lymphadenopathy: You can also have enlarged lymph nodes in the back portion of your mediastinum.
  • Extramedullary hematopoiesis (EMH): In rare cases, masses can form from bone marrow.
  • Neuroenteric cyst: This is a rare growth, consisting of various tissue types.
  • Conditions affecting your mid-spine (paravertebral conditions): These include infectious, malignant and traumatic abnormalities that appear in the middle of your spine (thoracic spine).
  • Blood vessel conditions: These include aortic aneurysms.

Who is affected by mediastinal tumors?

Most people diagnosed with mediastinal tumors are between the ages of 30 and 50. Still, these tumors can develop at any age and form from any tissue that exists in or passes through your chest cavity.

In adults, most tumors form in the anterior (front) mediastinum and are cancerous lymphomas or thymomas.

In children, most tumors form in the posterior (back) mediastinum. These tumors often begin in the nerves and aren’t cancerous.

How common are mediastinal tumors?

Mediastinal tumors are rare, occurring in less than 1% of the population. Most form in the anterior (front) part of your mediastinum. The most common types are thymomas, benign mediastinal cysts and lymphomas.

Is a mediastinal tumor serious?

Due to their location, mediastinal tumors that aren’t treated can cause serious problems, even if they’re not cancerous. These issues include spreading to your heart, pericardium (the lining around your heart) and great vessels (the aorta and vena cava). Tumors in your posterior (back) mediastinum can place pressure on your spinal cord.

Only about 25% of mediastinal masses are cancer. However, the chance of a malignant tumor increases if it’s in the front part of your mediastinum. Approximately 60% of anterior mediastinal masses are cancerous.


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Symptoms and Causes

What are the symptoms of a mediastinal tumor?

Almost 40% of people with mediastinal tumors don’t notice symptoms. Instead, healthcare providers often discover these tumors incidentally during chest X-rays performed for other reasons.

Symptoms often result from the tumor putting pressure on surrounding structures, like your heart, airway or spinal cord. Generally, children experience symptoms more commonly than adults. Malignant tumors cause symptoms more often than benign tumors.

Symptoms of a mediastinal tumor may include:

What causes mediastinal tumors?

Mediastinal tumors form for different reasons, including:

  • Out-of-control cell growth: Malignant and benign tumors form when cells multiply out of control, producing overgrowths. Researchers don’t always know what causes cells to start growing atypically.
  • Response to an underlying condition: Mediastinal tumors may form in response to inflammation or an underlying infection or condition. This can be the case with lymphadenopathy.
  • Atypical tissue development before birth: Mediastinal tumors may be congenital, or present at birth. Pericardial cysts, bronchogenic cysts and germ cell tumors are all congenital conditions.


Diagnosis and Tests

How is a mediastinal mass diagnosed?

When a mediastinal mass, or tumor, appears on a chest X-ray, healthcare providers often perform additional tests, like imaging or bloodwork, to learn more about it. Your healthcare provider may also perform tests if you have symptoms and a medical history that suggests a mediastinal mass.

The tests most commonly used to diagnose and evaluate a mediastinal tumor include:

  • Chest X-ray: Reveals masses in your mediastinum.
  • Computed tomography (CT) scan with an IV contrast agent: Shows the mass in more detail than a chest X-ray can, including how the tumor affects other structures inside your chest. This information can help your provider plan treatment.
  • Magnetic resonance imaging (MRI): Can show whether a mass is placing pressure on nearby tissue or invading nearby tissue (as with cancer).
  • Positron emission tomography (PET) scan: Can help healthcare providers identify certain mediastinal tumors, like lymphomas.
  • Blood tests: Can reveal if your blood contains proteins or enzymes associated with certain types of tumors (tumor markers).
  • Biopsy: Collecting a sample from the mass can reveal the type of tissue that makes up the tumor. For example, a biopsy can reveal if a tumor contains cancer cells. Biopsy procedures include CT-guided needle biopsy, esophagoscopy and bronchoscopy.
  • Mediastinoscopy with biopsy: This procedure allows your provider to view your mediastinum by inserting a lighted tube into your chest. Then, they remove tissue samples for testing.

Management and Treatment

What is the treatment for a mediastinal mass?

Treatment for mediastinal tumors depends on the type of tumor, its location, its stage (if it’s cancerous) and your symptoms. Surgery is the most common treatment.

  • Surgery: Cancerous tumors, tumors placing pressure on nearby organs or tissue, and tumors causing symptoms will likely need to be removed. Thymomas, thymic carcinoma, neurogenic tumors and other masses that cause symptoms often require surgery. Your healthcare provider may recommend surgery that involves an incision (cut) through your breastbone, called a sternotomy. Or they may recommend minimally invasive surgery to treat mediastinal tumors called video-assisted thorascopic surgery (VATS).
  • Radiation therapy: Radiation directs high-energy X-ray beams toward tumors, destroying them. You may receive radiation alone or with other treatments, like surgery. Depending on your cancer stage, you may receive radiation for thymomas, thymic cancer or lymphoma.
  • Chemotherapy: Chemotherapy drugs kill cancer cells and shrink tumors. Chemotherapy treatments are commonly used to treat thymic cancers.
  • Antibiotics: You may need antibiotics if your mediastinal mass results from an infection, as may be the case with lymphadenopathy.
  • Watchful waiting: Your healthcare provider may monitor the tumor instead of treating it directly if it’s benign and not causing symptoms.



How can I prevent mediastinal tumors?

Mediastinal masses aren’t preventable. But you can improve your chance of successful treatment if a healthcare provider finds your tumor early. See a healthcare provider if you have shortness of breath, coughing or other symptoms lasting longer than two weeks.

Outlook / Prognosis

What is the outlook for people with mediastinal tumors?

Every type of tumor is different. The outlook varies based on the type of tumor, whether the tumor’s cancerous and your general health.

Ask your healthcare provider about likely treatment outcomes. If you have a cancerous tumor, like a thymoma or lymphoma, ask your healthcare provider about cure rates and survival rates based on your unique diagnosis.

Living With

What questions should I ask my doctor?

Questions to ask include:

  • What type of mediastinal tumor do I have?
  • Is the tumor malignant or benign?
  • Will the tumor require treatment?
  • What types of treatment would you recommend?
  • What are the benefits and risks of potential treatment options?
  • What outcomes should I expect from treatment?
  • Should I look for signs of complications (from either the tumor or treatment)?

A note from Cleveland Clinic

Various tumors can form in your mediastinum. Some are serious and require immediate treatment. With others, you may not experience symptoms or need treatment at all. Your healthcare provider can explain your tumor type and whether it’s serious. Often, your provider can remove tumors causing symptoms with minimally invasive procedures like video-assisted thoracic surgery (VATS). Ask your healthcare provider about likely outcomes based on the type of tumor you have.

Medically Reviewed

Last reviewed on 12/13/2022.

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