[Benign mediastinal tumors].

Most of benign mediastinal tumors are asymptomatic; however, sometimes we encounter emergent cases. In this article we discuss with regard to the situation that benign mediastinal tumors with severe symptoms need to be treated emergently. Any benign mediastinal tumors can cause respiratory and cardiac failure as they grow large enough to compress surrounding structures. It is very unique that the symptoms are relieved or worsen according to the patients' position. Rupture of mature teratoma is another situation which necessitates emergent therapy. The symptoms due to rupture depends on the site, that is pericardial space, intrapulmonary, and thoracic cavity. The mechanism of rupture is suspected to autolysis, infection, and necrosis of the tumor. Anesthesia is an important issue in treating such huge mediastinal tumors, because general anesthesia using muscle relaxants can introduce acute respiratory or cardiac failure. Patient's position is again very important, for example, in the patients with orthopnea anesthesia is sometimes initiated and the patient is intubated in sitting position. Although it is rare, we must be aware of these emergent situations when we treat patients with benign mediastinal tumors.