FDG-PET/CT of schwannomas arising in the brachial plexus mimicking lymph node metastasis: report of two cases

BACKGROUND: Schwannoma is a tumor that develops on peripheral nerves or spinal roots. Although any part of the body can be affected, axillar and supraclavicular lesions are unusual for schwannoma. We report two cases of schwannoma arising in the brachial plexus, which were detected by (18)F-fluorodeoxyglucose positron emission tomography and computed tomography (FDG-PET/CT). CASE 1: A 75-year-old Japanese woman showed high FDG accumulation in a subclavicular or axillary lesion found by FDG-PET/CT. Axillar-subclavicular lymph node metastasis was suspected and surgical excision was performed. Histological evaluation revealed schwannoma. CASE 2: A 75-year-old Japanese woman was diagnosed with suspected primary lung cancer with brain metastases. She showed high FDG uptake at a subclavicular or axillary lesion found by FDG-PET/CT. Surgical excision was performed to arrive at a definitive diagnosis. The mass was located at the trunk of the brachial plexus and was identified as a schwannoma. CONCLUSION: Although schwannoma within an axillar or subclavicular lesion is relatively rare, brachial plexus schwannoma should be considered in the diagnosis of masses detected by FDG-PET/CT.