Thoracic Outlet Syndrome Caused by a Primary Tumour in the Brachial Plexus.

Thoracic outlet syndrome (TOS) caused by a primary brachial plexus tumour is very rare. A male politician in his 40s presented with numbness, left limb pain and positive Wright and Roos test results. Magnetic resonance imaging (MRI) revealed a tumour located just below the clavicle, compressing the subclavian artery during left arm elevation. Despite concerns regarding postoperative nerve deficits, surgery was performed because of worsening symptoms during the election campaigns. The pathology report revealed a schwannoma. Few reports have described TOS caused by primary tumours of the brachial plexus. While the decision to perform surgery for primary tumours of the brachial plexus requires careful consideration, surgery may be indicated in cases where the tumour location causes such symptoms. Level of Evidence: Level V (Therapeutic).