Mediastinum is an anatomical region which is surrounded by thoracic cavity, thoracic entry on the top, diaphragm at the bottom, vertebral column at the posterior, sternum at the front and parietal pleura at the side. Mediastinum is divided into two as superior and inferior with a line extending from the anguli sterni to the fourth inter-vertebral space. The inferior part is named in three parts such as the anterior, visceral and posterior (paravertebral) in proportion to the pericardial sac. Commonly, anterior and superior parts are associated with anterosuperior.
Aortic arch and branches, large venules lymphatics and fat tissue are located in anterosuperior mediastinum. The middle mediastinum includes heart, pericardium, phrenic nerves, trachea bifurcation and main bronchi, both lung hilus and lymph nodes. The posterior mediastinum includes esophagus, vagus nerves, sympathetic chain, descending aorta, azygos and hemiazygos venules, lymph nodes and fatty tissue.
Due to the presence of numerous organs and tissues in different structures in mediastinum; a wide variety of neoplastic masses, cystic lesions and infectious diseases might occur.
While 80% of mediastinal masses stem from secondary masses, the percentage of primary masses are 20%. Primary mediastinal masses can be seen in all ages. However; they are more common in the ages of 20-30 and in males. The incidence has been reported as 4-9/10,000.
Each mediastinal tumor or cyst has an origin in the mediastinum. It has been reported that 54-57% of the lesions are anterior, 9,5-20% of the median and 26-33.4% of the lesions are posterior to the mediastinum. Sabiston and Scott stated that neurogenic tumors are the most common mediastinal mass in the entire age group, and they sort thymoma as second, and lymphoma as the third. For Whooley and his colleagues; the sorting is thymoma, germ cell tumors and lymphoma.
For Duran Yıldız and his colleagues, the sorting is sequential thymic lesions, lymphoma and sarcoidosis. When compared with adults, in children; neurogenic tumors and non-Hodgkin lymphomas are frequent and pericardial cysts and thymomas are scarce. At the same time, the type and the frequency of tumors are closely related to localization. Usually, anterior mediastinal masses are tumors of thymoma, lymphoma, teratoma and germ cells. In middle mediastinum; lymphomas, bronchogenic and pericardial cysts are more frequent. And in posterior mediastinum; neurogenic tumors, bronchogenic and neuroenteric cysts are more frequent.
The division of mediastinal masses according to their places and their frequency are listed below.
Thymoma – Germ Cell Tumors
- Embryonal cell carcinoma
- Thyroid related lesions -Parathyroid lesions
- Metastatic Masses
- Granulomatous diseases
- Development cysts
- Pericardial cysts
- Bronchogenic cysts
- Vascular Mass and their enlargements
- Diaphragm hernia
- Neurogenic Tumors
- Peripheral nerve tumors
- Sympathetic ganglion-derived tumors
- Paraganglionic tissue tumors
- Esophagus lesions
- Diaphragm hernia
Surgical intervention is the most effective and the most recommended method for both histologic diagnosis and radical treatment (1,3,14).
For that matter; mediastinoscopy, anterior mediastinomy, transcervical mediastinoscopy, sternotomy, thoracotomy and VATS are the most frequently used surgical methods.
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