Thoracic outlet syndrome caused by schwannoma of brachial plexus.

Schwannomas are benign, usually slow-growing tumors that originate from Schwann cells surrounding peripheral, cranial, or autonomic nerves. The most common form of these tumors is acoustic neuroma. Schwannomas of the brachial plexus are quite rare, and symptomatic schwannomas of the brachial plexus are even rarer. A 47-year-old woman presented with a 1-year history of dysesthesia, neuropathic pain, and mild weakness of the right upper limb. Results of physical examination and electrodiagnostic studies supported a diagnosis as thoracic outlet syndrome. Conservative treatment did not relieve her symptoms. After 9 months, a soft mass was found at the upper margin of the right clavicle. Magnetic resonance imaging showed a 3.0×1.8×1.7 cm ovoid mass between the inferior trunk and the anterior division of the brachial plexus. Surgical mass excision and biopsy were performed. Pathological findings revealed the presence of schwannoma. After schwannoma removal, the right hand weakness did not progress any further and neuropathic pain gradually reduced. However, dysesthesia at the right C8 and T1 dermatome did not improve.