Case report: synovial sarcoma of the axilla with brachial plexus involvement.

Background: Synovial sarcoma is a rare soft tissue sarcoma which most commonly affects the extremities of young adults. Axilla involvement by this sarcoma is very rare especially with involvement of the brachial plexus. This combination adds to the challenge in approaching such tumors which might significantly affect survival and function.

Case Presentation: Herein, we present a 48-year-old female patient who presented with an isolated painless lump in her right axilla. Initially, her workup, looking for possible breast cancer, included fine-needle aspiration (FNA) which did not provide the diagnosis. Core-needle biopsy, performed later, revealed monophasic synovial sarcoma. Her workup studies revealed no metastasis. Then, through extensile deltopectoral approach, the tumor was dissected out from within the brachial plexus. Ulnar nerve was sacrificed in order not to compromise the surgical margins which were confirmed tumor free by final pathology. The patient did not receive chemotherapy or radiation upon consultations with medical and radiation oncology teams. Her follow-up revealed no tumor recurrence with no restriction of her right shoulder motion.

Conclusion: Our case report represents a very rare occurrence of synovial sarcoma in the axilla with involvement of the brachial plexus. When clinical and radiological findings are suggestive of soft tissue sarcoma of the axilla, we recommend getting core-needle biopsy rather than fine-needle aspiration for earlier diagnosis. Early referral and multidisciplinary approach may contribute to better management.