The mediastinum is the space in the middle part of your chest cavity (thorax) that contains your heart, aorta, esophagus, thymus, thyroid, trachea, lymph nodes and nerves. It separates your lungs, and is surrounded by your breastbone (sternum) in the front, your spine in the back and your lungs on either side.
Whether benign or cancerous, mediastinal tumors require a specialized, multidisciplinary team of surgeons, oncologists, and other specialists to diagnose accurately and treat optimally. Mediastinal tumors can occur:
- In any of the structures located inside the mediastinum, including the heart, thymus, esophagus, trachea and tissues surrounding them.
- In any of the mediastinal tissues, such as nerves, connective tissues, lymph nodes and lymph vessels.
- In cells that move through the mediastinum during development.
- When cancer cells metastasize from other tumors in other parts of the body, such as the lungs, head and neck, breast, thyroid, kidney or prostate.
What causes mediastinal tumors?
Mediastinal tumors in general are rare. Because of their location, however, they may cause problems if left untreated, even if they are not cancerous.
While doctors don’t know the exact cause of any cancer, the causes of mediastinal tumors are connected to where they form in the mediastinum, which is separated into three sections: anterior, middle and posterior. Different kinds of mediastinal tumors develop in each of these sections.
Most mediastinal tumors in adults occur in the anterior (front) mediastinum, usually as lymphomas or malignant thymomas. These growths often develop from an enlarged lymph node or an abnormal growth in the thymus, thyroid, parathyroid or other gland, and may begin as cysts in the bronchus, esophagus, or pericardium (the sac that houses the heart).
Common types of mediastinal tumors and cancers
- Thymomas and thymic cysts are mostly benign, and associated with autoimmune conditions such as myasthenia gravis, rheumatoid arthritis and lupus. They tend to grow slowly and are typically removed surgically.
- Thymic carcinoma (also called type C thymoma) is an aggressive cancer of the thymus that usually spreads quickly and has a high risk of recurrence.
- Thymic carcinoids are neuroendocrine cancers that account for 2% of all mediastinal tumors and 5% of thymic cancers.
- Lymphomas are cancers of the lymph glands that can develop in the mediastinum as Hodgkin's disease and non-Hodgkin’s lymphoma.
- Neurogenic tumors begin in cells that make up the nervous system and represent about 25% of all mediastinum tumors. Most are not cancerous and treated with surgery.
- Germ cell tumors form from cells in the sex organs that did not grow properly during gestation, and can develop anywhere in the body, including the mediastinum.