A case of leiomyosarcoma originating from a bronchogenic cyst: A case report.

Mediastinal leiomyosarcoma is an aggressive tumor that primarily occurs in the posterior mediastinum. A bronchogenic cyst is a benign lesion that often develops in the mediastinum close to the thoracic trachea and has been reported to be the origin of certain malignancies. The present study reports an extremely rare case of an anterior mediastinal leiomyosarcoma that was considered to have originated from a bronchogenic cyst. An 82-year-old woman complained of chest pain, presenting an abnormal 70 mm mass shadow in the anterior mediastinum of a chest CT scan. Mediastinal tumor resection was performed and the tumor was diagnosed as a leiomyosarcoma. As the tumor was located adjacent to a bronchogenic cyst, it was considered to have originated from the remnant tissue of the cyst. Recurrent lesions were noted in the right lower lobe on CT scan 24 months after surgery.