Thoracic outlet syndrome caused by superior mediastinal mass: A case report

Thoracic outlet syndrome (TOS) caused by superior mediastinal soft tissue mass has never been reported in the literature, the aim of this study is to discuss a case of TOS caused by a superior mediastinal mass in which the histopathological examinations of the mass showed vascular malformation.

A 45-year-old female presented with left upper limb pain and numbness for three months, associated with swelling and attacks of shortness of breath. Imaging studies showed soft tissue mass involving the superior mediastinum. The condition of the patient deteriorated and the signs and symptoms of TOS became clearer, all provocative tests and nerve conduction studies were positive. The patient underwent thoracic outlet decompression. The patient did not respond and the symptoms deteriorated further. After a multidisciplinary board discussion, the patient was prepared for median sternotomy under general anesthesia. A total resection of the mass was done. The patient was totally relieved a few hours after the operation.

The etiology of TOS can be multifaceted. Several factors contribute to its onset, and these can be categorized as congenital or acquired. Congenital causes include anatomical anomalies such as a cervical rib, or an elongated transverse process of the cervical vertebrae. These anatomical deviations can reduce the size of the thoracic outlet and make it prone to compression.

Although it is rare, TOS could be due to superior mediastinal mass and the treatment of choice is total resection either through median sternotomy or thoracoscopic procedure.