[Mediastinal leiomyosarcoma].

Primary mediastinal leiomyosarcomas are malignant sarcomas with unknown etiology not deriving from the smooth muscle fiber of the esophagus, trachea or main vessels. Very few cases have been reported in the literature and, although they are clinically unspecific, their histology is unique. The case described here is a 66-year-old woman with a leiomyosarcoma localized at the medium and posterior mediastinum, clinically presented as a mediastinal emergency.