late miscarriage後の巨大な初期子宮筋腫の膣切除

Uterine myomas are common benign tumors in women of reproductive age and may undergo degenerative changes during or after pregnancy. In rare cases, rapid growth and necrosis can complicate the clinical course and pose significant risks for infection and fertility. We report the case of a 29-year-old nulliparous woman who presented two months after a late miscarriage at 15 weeks of gestation with severe abdominal pain and a necrotizing uterine fibroid. Imaging revealed a large type 2 myoma, initially classified as type 3, according to the International Federation of Gynecology and Obstetrics (FIGO) classification, with central necrosis, prolapsing through the cervix into the vagina. Despite broad-spectrum antibiotics, symptoms persisted, and inflammatory markers increased. A fertility-preserving vaginal myomectomy was performed, allowing complete removal of a 120 mm necrotic fibroid. Postoperative recovery was uneventful, and follow-up imaging at three months showed only a small stable intramural remnant. The uterine cavity appeared normal on hysteroscopy, and the patient remained asymptomatic. Necrotizing fibroids following miscarriage pose diagnostic and therapeutic challenges. Magnetic resonance imaging (MRI) provides essential information for surgical planning, and vaginal myomectomy can be a fertility-preserving alternative when the fibroid becomes nascent. This case illustrates that even FIGO type 3 fibroids can be effectively managed by vaginal myomectomy. The myoma may convert to a FIGO type 2 myoma under pregnancy-related hormonal stimulation and subsequent necrosis, and may become infected, forming a "pyomyoma nascent." In selected patients, this approach enables rapid infection control, avoids hysterectomy, and preserves fertility.