Iranshahr University of medical sciences Scientific Journal of Medical Sciences 2783-4921 2 4 2023 12 01 Primary Carcinosarcoma of the breast: report a very rare case 1001 1007 EN Manouchehr Aghajanzadeh Journal Article 2023 12 11 2023 12 16 Background: Sarcoma of the breast is a rare malignancy with heterogeneous histology. angiosarcoma is the most common type of sarcoma of the breast secondary from previous radiation.There is limited clinical and survival information from other types of breast sarcomas. Case Presentation: Here we present A 56-year-old woman which presented with a mass in her right breast. On examination the tumor was not fixed to chest wall. But skin over mass was erymatous and with nipple retraction.A cor-needle biopsy was performed which showed leiomyosarcoma. After IHC the difintive diagnos was sarcoma. A radical resection of mass with radical mastectomy and axillary dissection were performed ,in permanent pathology all margins was free of tumor .After surgery patient refer to radio oncologist for irradiation therapy Conclusions: Surgical resection seems to be the most important treatment modality in sarcoma of the breast. Radiation therapy added a minor survival benefit to the patients who received surgical resection.