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Mediastinal Disease
This section discusses diseases of the mediastinum along with the diagnostic and therapeutic tests available for its treatment.
The mediastinum refers to the area in the middle of your chest. There are many organs and structures which are in the mediastinum, including the heart, esophagus, thymus gland and trachea (main breathing tube which goes from your mouth/throat to your lungs).
Tumors or masses are the abnormal growth of cells from tissues in your body. These growths can be malignant, which means cancerous, or benign, which means non-cancerous. When masses or tumors arise in the middle part of your chest they are called mediastinal masses or mediastinal tumors. In some circumstances, such as myasthenia gravis, there may be a proliferation of cells of the thymus, called thymic hyperplasia.
Evaluation of mediastinal masses or tumors
Many of these masses or tumors are found on routine chest x-rays and patients are asymptomatic. In this instance, there is an abnormal shadow or widening of the mediastinum. This may prompt further investigation with a more detailed x-ray called computerized tomography (CT scan) or magnetic resonance imaging (MRI). If a mediastinal mass or tumor is identified, depending on your history and physical exam, further investigation may be warranted. Blood tests and other non-invasive tests may also be necessary for any individual patient. A thoracic surgeon is a specialist who is able to assist in the diagnosis and treatment of tumors of the chest, including the mediastinum. It is important to seek the opinion of a thoracic when a mediastinal mass is found, prior to undergoing any invasive test or biopsy.
Types of mediastinal Masses
There are a number of types of mediastinal masses, as seen in chart 1. (Be able to enlarge chart) Based on one's history, physical exam and CT scan results, a diagnosis can be narrowed to 1 or 2 entities, in most cases. Certain disease states may also be affected by normal tissue in the mediastinum, as in the case of myasthenia gravis being affected by the thymus gland.
Mediastinal Masses
Anterior Mediastinum
Thymoma
(http://www.nci.nih.gov/cancerinfo/types/malignantthymoma/)
Thymic cysts
Thymic remnants
Thymic hyperplasia (as seen in myasthenia gravis)
Lymphomas ( http://www.nci.nih.gov/cancerinfo/types/non-hodgkins- lymphoma)
Germ-cell tumors
( http://www.nci.nih.gov/cancerinfo/types/extragonadal-germ-cell )
Seminomatous
Nonseminomatous
Teratomas
Thyroid goiters
Mesenchymal tumors
Middle mediastinum
Lymphoma
Foregut cysts
Bronchogenic cysts
Pericardial cysts
Posterior Mediastinum
Neurogenic tumors
Foregut cysts
Esophageal cysts
Thymoma
Biopsy options
Once a mediastinal mass or mediastinal tumor has been imaged using a CT scan or MRI and you have been evaluated by a thoracic surgeon, a tissue diagnosis to specifically classify the type of mass or tumor may be warranted. The tissue is examined by pathologist, a physician who specializes in examining tissue and cells under a microscope, for a diagnosis. In some cases a tissue biopsy is not necessary and may even be contraindicated
There are three main methods used to perform a biopsy.
• Percutaneous biopsy - is a procedure performed by an interventional radiologist under CT scan guidance. The patient is awake during the procedure, while a small needle is placed between your ribs and a small sample of the mass is taken.
• Thoracoscopic mediastinal biopsy- is a procedure performed in the operating room with the patient completely asleep. A small camera, the size of a pencil, is placed between the ribs in your armpit and the mass can be directly examined and a small piece can be removed for examination.
• Open mediastinal mass biopsy (Chamberlein procedure) - is a procedure performed in the operating room with the patient completely asleep. A small incision is made next to your sternum (breastbone) and a small piece can be removed for examination.
All three options may be available, depending on the individual patient and the ability of the surgeon and institution to offer all of these services.
Treatment of mediastinal masses and tumors
After complete evaluation and diagnosis, a number of treatment options may be available. Some types of tumors, lymphomas, usually respond best to chemotherapy as the primary choice, while others, neurogenic tumors or thymoma are usually best treated with surgery. There are some occasions when radiation therapy may be beneficial or combinations of surgery, chemotherapy and radiation therapy are necessary. Discussed below are a number of surgical treatment options available for removal of tumors or masses when appropriate. Our group has a large experience with all of these procedures and will discuss these options with you based on your individual evaluation and needs.
Surgery
Traditionally surgery for tumors of the chest required large incisions called sternotomies, dividing the breast bone, or thoracotomies dividing the ribs. In some cases these types of incisions are necessary to safely and effectively remove the tumors and masses. Over the last decade a number of minimally invasive approaches have been developed for mediastinal tumors, as well as for treatment of lung disease, lung cancer and many types of heart surgery.
Traditional open surgery
Resections of large mediastinal masses or tumors are usually approached through incisions called sternotomies, dividing the breast bone or thoracotomies dividing the ribs. These approaches are still the most commonly performed and are necessary for larger tumors and masses. These approaches allow access to the entire chest cavity including the heart, great vessels, and lungs. The type and size of the tumor will affect if any other structures, such as the pericardium or lung need to be resected.
Minimally Invasive Surgery
Mini-sternotomy or hemi-sternotomy is when the upper part of the sternum, or breastbone, is divided. This allows similar access to the mediastinal structure but results in less pain and shorter recovery periods compared to traditional sternotomy.
Mini-thoracotomy is a broad term, which may include, muscle-sparing and /or non-rib spreading incisions. These approaches also lessen pain and recovery compared to traditional postereolateral thoracotomies.
Video-assisted thoracoscopic surgery (VATS) is a procedure using a small camera and pencil-sized incisions to look into the chest cavity and biopsy and resect mediastinal tumors or masses. VATS has also been used to resect lung cancer, lung nodules, lung biopsies, and problems of the esophagus, including cancer. Resecting mediastinal tumors and masses, including the thymus for myasthenia gravis, is able to be performed using VATS techniques by advanced thoracoscopic and minimally invasive thoracic surgeons.
Robotic or Totally Endoscopic Surgery
More recently, robotic surgery has been used to treat many mediastinal diseases, including thymectomy for myasthenia gravis, as well as lung, esophageal, and cardiac diseases. Using the da Vinci Surgical System, a camera and two small pencil sized instruments are placed inside the chest cavity similar to thoracoscopic or VATS surgery. This robotic system, which is FDA approved, allows improved visualization and improved dissection and suturing capabilities compared to VATS. These abilities may even be improvements over open surgery because of the increased magnification and precise dissection techniques.
Our surgeons were one of the first groups to develop, use, and publish on robotic surgery for all forms of thoracic and cardiac surgery including thymectomy for myasthenia gravis, mediastinal evaluation of tumors, resection of lung cancer and various cardiac procedures.
Transcervical approaches to the mediastinum are used for certain types of tumors or masses. The most common use of this approach is for thyroid goiter which extends into the mediastinum from the neck. Most of the resection of the thyroid can be done through a single neck incision, even when it extends in to the neck. This approach can also be used to perform a thymectomy for myasthenia gravis in certain patients. An incision is made in the neck and the dissection can be performed by looking under the sternum (breastbone), without breaking it, to resect the thymus.
Myasthenia Gravis
http://www.myasthenia.org/index.htm - http://pages.prodigy.net/stanley.w a y/myasthenia/
Areas of Specialty