[Giant Mature Cystic Teratoma Causing Loss of Consciousness before Surgery].

A 30-year-old woman who presented loss of consciousness was diagnosed as having large anterior mediastinal tumor. Computed tomography (CT) showed a 17.0×13.0×7.3 cm cystic mass with internal calcification in the anterior mediastinum that was markedly compressing the heart, great vessels, trachea and bronchi. A mature cystic teratoma was suspected, and the mediastinal tumor was resected through a median sternotomy. At the induction of anesthesia to prevent the development of the respiratory and circulatory collapse, the patient was consciously intubated under the right lateral decubitus position while preparing for percutaneous cardiopulmonary support by cardiac surgeons, and the surgery was safely performed. The tumor was pathologically diagnosed as a mature cystic teratoma, and symptoms such as loss of consciousness have disappeared.