TY - JOUR T1 - 368 Primary breast carcinosarcoma JF - International Journal of Gynecologic Cancer JO - Int J Gynecol Cancer SP - A152 LP - A152 DO - 10.1136/ijgc-2019-IGCS.368 VL - 29 IS - Suppl 3 AU - N Tsoukalas AU - K Tsapakidis AU - E Aravantinou-Fatorou AU - P Baxevanos AU - M Tolia AU - I Binas AU - M Kiakou AU - M Galanopoulos AU - I Kostakis AU - E Tsiampas AU - A Karameris Y1 - 2019/09/01 UR - http://ijgc.bmj.com/content/29/Suppl_3/A152.2.abstract N2 - Objectives Breast carcinosarcoma is a rare malignancy, accounting for approximately 0,08–0,2%, of all breast tumors. It consists of two cell lines, one of epithelial origin (carcinoma) and another of mesenchymal origin (sarcoma). It is a type of metaplastic mammary carcinomas and it is probably derived from myoepithelial cells.Methods Case report of a breast carcinosarcoma.Results A 65-year-old woman presented to our hospital with a 2-month history of rapidly growing mass in her left breast. Neither her medical nor family’s history was positive for malignancies. She underwent an FNA, which was positive for adenocarcinoma, followed by a lumpectomy with axillary lymph node dissection. The pathology showed an undifferentiated neoplasm and the immunohistochemical cell staining was positive for keratin, SNA, Vimentin, S-100. Finally, the hormone receptor analysis was triple negative, suggesting beyond the others the diagnosis of breast carcinosarcoma. There was no evidence of metastatic foci except from a positive lymph node, indicating a IIIa stage. She received adjuvant treatment with chemotherapy and radiotherapy but sixteen months later she presented with a distant recurrence of both lungs and sternum. She received first line treatment with chemotherapy and radiotherapy to sternum.Conclusions Aggressive behavior, chemoresistance and ominous prognosis seem to be the main characteristics of breast carcinosarcomas. Of course, the prerequisite for treatment is the right diagnosis that distinguishes this tumor from other types of breast cancer. ER -