Mediastinal tumor is a general term for various tumors or cysts that occur in the mediastinal region. The mediastinal area is within the thoracic cavity, behind the sternum, in front of the spine and in the middle of the thoracic cavity on both sides. Mediastinal tumors include primary tumors and metastatic tumors. Common mediastinal tumors include thymoma, neurogenic tumors, teratoma, lymphoma, and abnormally enlarged thyroid gland. The normal mediastinum contains thymus, adipose tissue, lymph nodes, lymphatic vessels, heart, trachea, esophagus, large blood vessels, etc. Each tissue and organ has the possibility of tumor. In adults, the thymus gland itself may degenerate and shrink, but in a pathological state, it may grow and enlarge, forming a thymoma, which can be benign or malignant, sometimes causing generalized muscle weakness and requiring surgery to eradicate. Adipose tissue is distributed throughout the body, and tumors may occur, most of which are benign and few are malignant. Most lymphoid tissue tumors are malignant, but can now be controlled by chemotherapy. Teratomas and staphylomas occur in female patients, mostly benign, and are metastases from female reproductive system tumors. Hair, teeth, bones, etc. can sometimes be seen within these tumor tissues. Neurogenic tumors, which may be abnormal growths of various nerve tissues on the spinal cord from within the spine, are mostly benign and a few are malignant. As mentioned above, mediastinal tumors are both benign and malignant. The common ones are thymoma, neurogenic tumor, lymphoma, teratoma, goiter, etc.