Primary breast synovial sarcoma: a rare primary breast neoplasm

A primary synovial sarcoma based on the breast is rare. The usual tumours on the breast are carcinomas. Synovial sarcomas account for about 6–9% of soft tissue sarcomas and most commonly develop in the extremity of young adults (80%). The other 20% of synovial sarcomas can arise in non-extremity sites (trunk 8%, retroperitoneal/abdominal 7%, head and neck 5%) but synovial sarcomas can develop in almost any other anatomical location. We report a case of a young woman who presented with a suspected common breast tumour and started treatment of this tumour with carcinoma neoadjuvant chemotherapy. We were surprised when the pathologist identified a synovial sarcoma in the histopathology study.