[A case of anterior mediastinal mature teratoma containing air because of penetration to the lung].

A case of anterior mediastinal mature teratoma containing air because of penetrating to the lung was reported. The patient was a 28-year-old woman. The chest X-ray film on admission showed a homogeneous mass in the anterior mediastinum. This shadow changed to cystic one after ten days later. The tumor was removed together with adhering part of the left lung and pericardium through median sternotomy. Histologically, the wall of cysts contained sebaseous glands, bronchial glands and pancreatic tissue containing both exocrine and endocrine elements.