Dayal, Seema2026-06-052026-06-052026-03European Journal of Clinical and Experimental Medicine T. 24, z. 1 (2026), s. 217–2212544-1361https://repozytorium.ur.edu.pl/handle/item/12523Not required for a case report but ethical clearance on histopathology evaluation of hysterectomies specimens was already taken (reference no.30/UPUMS/Dean/2017-18 )Introduction and aim. Carcinosarcoma of the uterus is a rare and aggressive monoclonal tumor composed of both epithelial and mesenchymal components. It is associated with poor prognosis and shows a marked tendency for early metastasis and recurrence, posing a significant challenge in gynecological oncology. This study aimed to identify the precise clinicopathological features of uterine carcinosarcoma that may facilitate accurate diagnosis and, ultimately, timely patient management. Description of the case. A 53-year-old nulliparous woman presented with vaginal bleeding and an abdominal mass. Clinically, the case was initially diagnosed as leiomyoma uteri. The patient underwent hysterectomy, and the specimen was submitted for histopathological examination. Histopathology suggested a malignant mixed Müllerian tumor (homologous type). Immunohistochemistry was performed to confirm the diagnosis and to exclude differentials such as endometrial carcinoma. The tumor was positive for cytokeratin, vimentin, cyclin D1, and CD10, while negative for p53 in both components. The coexistence of epithelial and mesenchymal elements of common embryonic origin, together with the absence of p53 expression, confirmed the monoclonal nature of the tumor. Conclusion. Accurate diagnosis of uterine carcinosarcoma requires the combined use of clinical evaluation, histopathology, and immunohistochemistry, which are essential for guiding optimal therapeutic interventions and determining prognosis.engAttribution-NonCommercial-NoDerivatives 4.0 Internationalhttp://creativecommons.org/licenses/by-nc-nd/4.0/carcinosarcomacorpus uterushysterectomyimmunohistochemistrymixed Mullerian tumorarticle10.15584/ejcem.2026.1.7