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The mediastinum is an anatomical region surrounded by the thoracic inlet at the top, the diaphragm at the bottom, the vertebral column at the back, the sternum/belly anteriorly, and the parietal pleura at the sides. The heart, great vessels, trachea, esophagus, fatty tissue, lymph nodes, and some nerves are within this space. It is divided into the anterior, middle, and posterior mediastinum. The anterior cavity contains the thymus gland. The location of the mediastinal mass affects the surgical method we prefer.
What are Mediastinal Masses?
|Anteriyor mediasten||Orta mediasten||Posteriyor mediasten|
|Germ cell tumors||Metastatic masses||Tumors of peripheral nerve origin|
|Teratoma||Granulomatous diseases||Tumors of sympathetic ganglion origin|
|Seminoma||Developmental cysts||Paraganglionic tissue tumors|
|Embryonal cell cancer||Pericardial cysts||Esophageal lesions|
|Choriocarcinoma||Bronchogenic cysts||Diaphragmatic hernia|
|Lymphoma||Vascular mass and enlargements|
|Thyroid-related lesions||Diaphragmatic hernia|
What are the most common mediastinal masses?
The most common lesions in the mediastinum are generally metastasis/spread of cancers, especially lung cancer (small cell lung cancer, squamous cell cancer, etc.) to the lymph nodes. Lymph node cancer, which we call lymphoma, is a common mediastinum tumor. It is frequent in granulomatous diseases (such as tuberculosis and sarcoidosis). Tumors arising directly from mediastinal tissues are rare, around 20%. 80% are secondary. Thymomas (thymus tumors) in the anterior mediastinum are common.
In the posterior mediastinum, benign tumors originating from the nerves are the most common. Germ cell tumors are common in young men.
What are the symptoms of a mediastinal mass?
These small lesions/masses/tumors are found incidentally because they are asymptomatic when they are small. The symptoms are usually nonspecific. The clinic of the patients varies depending on the structure of the lesion, its localization, compression or invasion of neighboring organs, or side effects of the endocrine system. The most common symptoms are; pain, cough, shortness of breath, swelling of the face and neck, and the veins becoming prominent.
- Fatigue, weight loss, fever, and night sweats are common in lymphoma.
- They do not give as much symptoms as growing in neurogenic tumors
- When anterior mediastinal masses are in large sizes, such as thymoma, they become asymptomatic. Sometimes we can detect thymoma when there are symptoms of Myasthenia Gravis disease.
What are the examinations performed in mediastinal masses?
- Chest x-ray
- Contrasted Thorax CT
- Magnetic resonance (MR): Beneficial for vascular invasion of the mass and cystic lesions.
- Laboratory tests such as,
- LDH, T3, T4, beta-HCG, alpha-fetoprotein (AFP)
- In germ cell tumors, beta-HCG, alpha-fetoprotein (AFP)
- PET-CT if the mass is malignant
- LDH, T3, T4, beta-HCG, alpha-fetoprotein (AFP)
How is the diagnosis/diagnosis made in mediastinal masses?
- Bronchoscopic Endobronchial Ultrasonography EBUS: Preferred for mediastinal lymph nodes
- Endoesophageal Ultrasonography /EUS: Mediastinal lymph nodes
- Tru-cut biopsy: A biopsy is performed by marking it under Computerized Tomography.
- Mediastinoscopy: It is performed under general anesthesia. Mediastinal lymph nodes are biopsied.
- Mediastinotomy: : It is performed under general anesthesia. With a 3 cm incision at the level of 2 ribs from the anterior side, plenty of biopsies from the masses in the anterior mediastinum.
- VATS / Thoracoscopy / Closed surgery: A piece is sampled through one or two incisions. With the VATS method, the relationship of the mass to the vessels also gives information about the surgery.
- Scalene biopsy: It is performed under local anesthesia. We perform mass/lymph node biopsy from the neck or supraclavicular region.
Note 1: If we suspect thymoma clinically and radiologically, we do not perform a biopsy. Thymoma has a capsule to prevent the tumor from spreading to the environment. When we do a biopsy, the capsule may be punctured, and cancer may spread. We recommend immediate surgery.
Treatment of Mediastinal Masses
It varies according to the tumor type.
- Preoperative (neoadjuvant) chemotherapy is followed by surgery, if necessary, for masses extending to the mediastinum.
- First choice in other mediastinal masses: Minimally Invasive Surgery Methods (Robotic and Thoracoscopic Surgery).
- Robotic Surgery
- Thoracoscopic Surgery/VATS
- Median sternotomy
1. Thoracoscopic /VATS
It is the most preferred method. It is a closed method by entering through two or three incisions.
- Note-2: VATS; the capsule mustn't be ruptured, especially in thymomas. If the capsule ruptures during the surgery, the risk of recurrence is high. Therefore, it should not be preferred if the tumor diameter is huge (average diameter: greater than 5 cm). When applied to giant tumors, tumor movements may spread cancer, so it would be better not to use it for tumors with vascular involvement, pericardium, and large-scale tumors.
Figure 1: Videothoracoscopic and robotic thymectomy surgery from our clinic.
2. ROBOTIC SURGERY
It has the same tiny holes and similar indications as VATS. The surgeon operates with small fractions with the da Vinci Robotic Surgery system. The surgeon performs the operation sitting at the console. A surgeon standing at the patient's bedside during the process helps the surgeon at the console.
The surgeon operates on a 3D image, and cameras enlarge the operation area 10-12 times. These tooltips can rotate 540 degrees around their axis and mimic the wrist movements of the human hand.
Picture 2: The surgeon performs the operation sitting at a computer console. In an operation, a surgeon and a nurse are at the patient's side and help the surgeon at the console.
This incision is preferred if mediastinal masses involve large vessels and are very large.
We use it sometimes if the tumor location is close to one side of the chest.