The image shows a high-grade leiomyosarcoma arising in the uterus. One can appreciate the cytologic atypia of the smooth muscle cells consisting of hyperchromatic pleomorphic nuclei with occasional prominent nucleoli. At least 2 mitotic figures can also be seen. Leiomyosarcomas are usually seen in older women as compared to leiomyomas. Unopposed estrogen stimulation appears to play a major role in their pathogenesis.