Introduction
Primary breast sarcomas are very rare, and primary breast osteosarcoma (PBOS) is still far less common. To the best of our knowledge, less than 150 cases of PBOS have been reported by this time; however, based on recent investigations, it is possible that even many of those cases were not really PBOS and they were some variants of metaplastic breast carcinoma. Indeed, they were considered as PBOS because of the lack of conducting a comprehensive histological and immunohistochemical (IHC) evaluation (1). Since there is no common consensus regarding the management of this specific kind of malignancy, reporting each case and its challenges could be helpful to provide more information about this type of aggressive and poor prognostic tumor.