Leiomyosarcoma: a rare malignant transformation of a uterine leiomyoma.

The malignant transformation of a uterine leiomyoma is still debated and, if it occurs, it is very rare. The case of a patient affected by one small leiomyoma is described. Diagnosis was made postoperatively on histopathological examination. The case reported here is meant to underline the need to keep all uterine myomas in check since the transition into leiomyosarcomas (LMSs) may occur with an evolution over a time period which has not been established so far. Specific receptors for luteinizing hormone/human chorionic gonadotropin (LH/hCG) have also been identified in the myometrium of several animal species, including humans. Conventional LMSs express estrogen receptors (ER), progesterone receptors (PR), and androgen receptors (AR) in 30-40% of cases. In comparison with other more common uterine malignancies, uterine LMSs bear some resemblance to type 2 endometrial carcinomas and high-grade serous carcinomas of ovary/fallopian tube origin, based on their genetic instability, frequent p53 abnormalities, aggressive behavior, and resistance to chemotherapy. It could be useful to understand with further researches if hormonal stimulation could be a contributing factor of uterine leiomyoma transformation into LMS. Until today the oncogenic mechanisms underlying the development of uterine LMSs remain elusive.