Low-grade endometrial stromal sarcoma combined with leiomyoma (stromomyoma): A bizarre tumor of the uterus in a premenopausal woman.

Objective: Uterine sarcomas are very rare malignancies, and when a hysterectomy is performed for benign causes, a risk of about 1/500 is mentioned for possible uterine sarcomas. Endometrial stromal neoplasms are a rare subgroup of uterine sarcomas that account for less than 10% of all uterine sarcomas. Mixed endometrial stromal and smooth muscle tumors, also known as stromomyomas, are defined as having at least 30% each of endometrial stromal and smooth muscle components. As a result, stromomyoma is an extremely rare malignant mixed mesenchymal tumor of the uterus. Both clinically and histologically, the differential diagnosis is challenging. Stromomyoma should be kept in mind in the differential diagnosis of large uterine masses, even if these masses are seen in an asymptomatic woman of reproductive age. In this study, we aimed to present this bizarre tumor of the uterus detected in a premenopausal woman.