Mediastinal mature cystic teratoma perforating into the lung.

Perforated cystic mediastinal teratoma is rare. The diagnosis of this condition and a clear demonstration of its associated complications are important for defining the surgical approach. We report the clinical manifestation, computed tomography (CT) and ultrasound findings of a case of mediastinal mature cystic teratoma perforating into the lung. Ultrasound features of teratoma-lung fistula have not been previously described. The pathological examination confirmed perforation of mediastinal teratoma into the lung without evidence of pulmonary invasion.