A Rare Case Report of Uterine Carcinosarcoma in Patient with History of Breast Carcinoma

Uterine carcinosarcoma (UCS), or malignant mixed Müllerian tumor, is a rare and aggressive uterine malignancy comprising malignant epithelial and mesenchymal components. We present the case of a 67-year-old postmenopausal woman with abdominal pain and anemia, and a history of breast carcinoma. Initial imaging suggested an endometrial polyp; biopsy was inconclusive. Persistent symptoms led to hysterectomy with bilateral salpingo-oophorectomy. Grossly, the uterus contained a bulky grey-white tumor (7x5x3 cm). Histopathology revealed serous adenocarcinoma (CK, p53 positive; ER negative) admixed with vimentin-positive homologous sarcoma, with >50% myometrial invasion; adnexa were uninvolved (FIGO stage IA). UCS has a poor prognosis and is occasionally linked to prior tamoxifen use, though hormonal therapy history was unavailable in this patient. This case highlights the need for suspicion of UCS in postmenopausal women with uterine masses and prior breast carcinoma, even without confirmed tamoxifen exposure. Early recognition and histopathologic confirmation are vital to guide management in this aggressive malignancy.