PT - JOURNAL ARTICLE AU - N Koufopoulos AU - S Kokkali AU - F Antoniadou AU - D Nasi AU - E Pigadioti AU - L Khaldi TI - EP213 Undifferentiated pleomorphic sarcoma of the breast: presentation of a case AID - 10.1136/ijgc-2019-ESGO.275 DP - 2019 Nov 01 TA - International Journal of Gynecologic Cancer PG - A182--A183 VI - 29 IP - Suppl 4 4099 - http://ijgc.bmj.com/content/29/Suppl_4/A182.2.short 4100 - http://ijgc.bmj.com/content/29/Suppl_4/A182.2.full SO - Int J Gynecol Cancer2019 Nov 01; 29 AB - Introduction/Background Undifferentiated pleomorphic sarcoma (UPS) is a malignant mesenchymal neoplasm presenting very rarely as a primary breast tumor. We present a case of UPS of the breast with aggressive clinical behavior.Methodology A 67-year-old patient was admitted to our hospital due to a palpable lump of the right breast. Imaging studies revealed a 7 cm multilobular mass. A lumpectomy was performed. On gross examination, the tumor was solid, white-gray and had a greatest dimension of 7.3 cm.Results On microscopic examination, the tumor consisted of spindle cells with alternating cellularity, high-grade atypia, and brisk mitotic activity. Immunohistochemical stains were positive for CD68, CD163, CD10 and negative for AE1/AE3, EMA, CK7, Ck34bE12, p63, SMA, Desmin, S100, CD31, CD34, and CD56. The diagnosis of UPS of the breast was made. The surgical margins were infiltrated. A month later she underwent a modified radical mastectomy. The surgical margins were infiltrated. The patient received first-line systemic therapy. After having received one cycle of systemic therapy, the tumor recurred locally. A third surgical operation was performed to achieve local control. The patient‘s condition deteriorated very rapidly. A month later she presented with metastatic disease to the lungs. The patient passed away due to respiratory insufficiency.Conclusion Primary breast sarcoma diagnosis may occasionally prove very challenging. Before making the diagnosis other more common entities (malignant phyllodes tumor, metaplastic carcinoma and metastatic sarcoma from another primary site) have to be excluded. Extensive tumor sampling, attention to histological detail paired with the use of the appropriate immunohistochemical markers will usually help in making the diagnosis. Similar to the case we present data found in the literature indicates that breast UPS show an aggressive clinical course and a high incidence of recurrence and metastasis.Disclosure Nothing to disclose.