Abstract
Large uterine fibroids that grow rapidly over a short period should be differentiated from uterine leiomyosarcoma, and their treatment remains controversial in women seeking to conceive. Here, we report two cases of uterine fibroids treated with short-term relugolix administration followed by myomectomy. Needle biopsy specimens obtained before relugolix administration showed no malignancy, and significant tumor shrinkage was observed following treatment. Both patients subsequently underwent myomectomy. One patient achieved a live birth 14 months after myomectomy, whereas the other experienced improvement in severe anemia, allowing her to prepare for pregnancy. Histological examination after relugolix administration revealed atrophic changes in spindle cells within the fibroids, characterized by nuclear crowding and decreased immunoreactivity for desmin and α-smooth muscle actin. The significant fibroid shrinkage observed after the short-term administration of relugolix provided a rationale for myomectomy, improved anemia, and facilitated appropriate uterine reconstruction, ensuring structural integrity for future pregnancies in women of reproductive age.