本文報告一位41歲女性，因持續兩週的下腹悶痛及腫塊求診，術後確診為子宮平滑肌惡性肉瘤，她在兩年半前曾接受腹腔鏡子宮肌瘤切除術，診斷為非典型子宮肌瘤。子宮平滑肌惡性肉瘤的發生率極低，目前超音波及電腦斷層尚無法和子宮肌瘤明確區分，而核磁共振是一個相當敏感的工具，因此若腫瘤超過8 cm或生長快速，宜進一步以核磁共振或以組織切片或直接手術探查。此外，非典型子宮肌瘤，雖多數為良性，但有進展為惡性肉瘤的可能，建議在術後至少5年內，每半年接受骨盆腔理學檢查，每年胸部X光攝影及骨盆腔影像學檢查，以早期發現復發或惡性的腫瘤。

We herein reported a 41-year-old woman presenting with two weeks of lower abdominal mass and dull pain. She underwent total hysterectomy with bilateral salpingo-oophorectomy, and the pathology examination revealed uterine leiomyosarcoma. The patient had a surgical history of laparoscopic myomectomy with a pathologic diagnosis of atypical leiomyoma of the uterus two and a half years ago.

The incidence of uterine leiomyosarcoma is very low. In the modern era, echography and computed tomography remain unable to clearly differentiate uterine leiomyosarcoma from leiomyoma, whereas MRI is a sensitive tool for diagnosis. Therefore, if a lower abdominal mass is more than 8 cm or rapidly growing, MRI, biopsy, or laparoscopic exploration, is strongly recommended. Moreover, while atypical leiomyoma of the uterus is mostly benign in nature, it has a high rate of recurrence and the potential of transformation into leiomyosarcoma. Hence, for early detection of recurrence, pelvic examination twice a year, annual chest X-ray, and pelvic imaging are recommended for at least 5 years postoperatively in these cases.