There are different types of mediastinal tumors, and their causes vary depending on where they grow in the mediastinum. This blog post discusses where mediastinal tumors grow and how they are diagnosed.
Superior Mediastinum lies within the upper third of the chest and is bordered by the thoracic inlet, inner aspects of the lungs, back of the sternum and front of the upper vertebral bodies. This area contains the thymus, trachea, esophagus, major arteries, veins and important nerves.
Mediastinum anterior (front)
The anterior mediastinum (front) is a compartment bordered in front by the sternum and behind by the spinal column. The thoracic inlet serves as the superior boundary, and the diaphragm serves as the inferior boundary. Growths within this compartment include:
Hodgkin’s disease and non-hodgkin’s lymphoma both fall under the category of cancer known as lymphoma,
Two thymic lesions are thymoma and a thymic cyst. Thymomas are encased in fibrous capsules and are typically benign tumors. However, about 30% of them might be more aggressive and grow outside the sac into nearby tissue. Thymomas are the most common tumors in this compartment.
Both males and females are susceptible to germ cell neoplasms, the vast majority of which (60 to 70%) are benign.Thyroid mediastinal mass: Usually, this is a benign growth, like a goiter (irregular growth of the thyroid gland) but may be cancerous.
Middle Mediastinum
The middle mediastinum is a compartment located between the lungs. It contains the heart and its great vessels, the trachea, esophagus, and thoracic duct. The middle mediastinum is surrounded by the pleura of each lung. Growths within this compartment may include:
A benign growth with rudimentary respiratory origins called a bronchogenic cyst. An enlargement of the lymph nodes in this area is known as mediastinal lymphadenopathy and may represent an infectious, inflammatory, or cancerous condition. A pericardial cyst is a benign growth that involves an outpouching of the pericardial sac around the heart.
Mediastinum posterior (back)
The mediastinum posterior (back) is a vital part of the body and contains many important organs.
The posterior mediastinum posterior is bordered by the diaphragm below, the vertebral column and the pericardial sac around the heart. This area is important because it contains the esophagus, aorta, veins, and lymphatics.
Three different types of neurogenic tumors—nerve sheath neoplasms, ganglion cell neoplasms, and preganglionic cell neoplasms—are the most common causes of posterior mediastinal tumors. Roughly 70% are benign.
Esophageal tumors may be benign or malignant. Examples of benign esophageal abnormalities include diverticulums, hiatal hernias, and achalasia. Vascular abnormalities may be due to an aortic aneurysm or aortic dissection.
The swelling of the lymph nodes is known as lymphadenopathy. A neurenteric cyst is an uncommon development with gastrointestinal and neurological components. Paravertebral abnormalities include thoracic spine anomalies that are infectious, malignant, or traumatic.
How Is a Mediastinal Tumor Diagnosed?
CT scans and magnetic resonance imaging (MRI) are imaging tests that can provide more detailed pictures of the inside of the chest. These tests can often show tumors that are not visible on a plain X-ray. PET scans use a radioactive marker in order to highlight abnormal areas of the body.
Endoscopy is a procedure that uses a thin, flexible tube with a light and camera at the end to look inside the chest.
Bronchoscopy involves the passage of the tube into the airways.
Esophagoscopy is the passage of the camera into the esophagus. Both procedures can be used to take biopsies (samples of tissue) from the tumor. A biopsy is needed to confirm the type of tumor which is crucial in determining treatment.
Blood tests, such as a complete blood count (CBC) and tumor markers, may also be done. Tumor markers are substances that are produced by some types of cancer cells. They can be found in the blood, urine, or other body fluids. However, not all tumors make tumor markers, and having a high level of a tumor marker does not necessarily mean that you have cancer.
CT-guided needle biopsy may be done if the tumor can be reached with a long, thin needle. During this procedure, the doctor uses the CT scan for guidance in order to accurately insert the needle through the skin and into the tumor. A small piece of tissue is then removed and sent to a laboratory for analysis.
Mediastinoscopy is an outpatient procedure that may be done if the tumor cannot be reached with a needle. In this procedure, the surgeon makes a small incision just above the breastbone and uses a scope to remove a small piece of the tumor. The tissue is then sent to a laboratory for analysis.
What happens after the biopsy results are back?
Once the biopsy results are available, your doctor will determine the next steps in your treatment. A benign growth may require no treatment or may require surgery if it is compromising adjacent organs.
If the tumor is cancerous, additional testing is often required to determine the stage of cancer. Treatment will depend on the type and stage of cancer. It may include surgery, radiation therapy, and/or chemotherapy.
Lawrence Schmetterer, M.D., F.A.C.S is a Board Certified Cardiothoracic Surgeon with more than three decades of experience in the treatment of these problems. Obtain additional information regarding the Symptoms, Causes, Treatment, and Prognosis of mediastinal tumors. Schedule a consultation now to discover more about the best treatment for you or a loved one who suffer from the mediastinal tumor.
