RESUMO
BACKGROUND: Schwannoma is an extremely rare benign tumour of the peripheral nervous system; its association with breast cancer is sporadic, and its association with the brachial plexus is extremely rare. CASE DESCRIPTION: The authors report a case of a patient with breast cancer associated with nodulation in the left supraclavicular fossa, and due to the clinical and radiological features, it was considered metastatic lymph node disease. The patient underwent neoadjuvant chemotherapy, with partial response of the breast. Surgical treatment included resection of the supraclavicular nodule, which was found to be a supraclavicular fossa schwannoma. The correct diagnosis, influences the radiotherapeutic planning. The unusual presentation led to diagnostic confusion in the present case, a fact that changed the breast treatment. CONCLUSION: The best of our knowledge it is the third description of brachial plexus schwannoma associated with breast cancer and the first with a synchronous association. The knowledge of this pathology and its potential to alter treatment justify the reporting of the present case.