Uterine adenosarcoma (UA) with sarcomatous overgrowth (ASSO) is a rare and aggressive disease. Herein, wereported the case of a young patient with advanced uterine ASSO.A 29-year-old woman with the diagnoses of endometrial polyp and adenomyosis underwent hysteroscopic endometrial polypectomy for the giant endometrial polyp. Postoperative regular ultrasound scan indicated thickened endometriumand an ill-defined mass with continuous enlargement in the myometrium of the posterior wall of the uterus, which was considered as an adenomyoma. Two years after hysteroscopy, she was re-admitted due to lower abdominal distension and large pelvic mass. At that time, she had taken oral short-acting contraceptives for 2.5 years.Magnetic resonance imaging (MRI) of the pelvis revealed an irregular mass with the size of 12*56*107 mm in the right annex area, without distinct border with the rectum, moreover, an uneven intrauterine echo that has no obvious boundary with uterine wall. Right ovarian cancer and adenomyoma were initially considered.The patient received transperitoneal retroperitoneal pelvic combined with total viscera resection, including uterus, bilateral appendages and rectum, omentectomy, appendectomy, lymphadenectomy, and ileostomy. Postoperative pathology confirmed ASSO in the uterine cavity and muscular layer, the whole cervical duct and the right adnexal. She underwent 2 systemic chemotherapy sessions after the surgery. The chemotherapy regimen was ifosfamide 2.5 g day 1 to 3, with liposomal doxorubicin 40 mg day 1.The final diagnosis was uterine ASSO, International Federation of Gynecology and Obstetrics stage IVa. The patient has been following-up so far, with no progression.Review of the case indicated that history of long-term oral short-acting contraceptives and giant endometrial polyps may be the high-risk factors for UA. For patients with high-risk factors, the follow-up ultrasound scan should be more frequently conducted. Moreover, 3D-ultrasound, MRI and outpatient hysteroscopy are recommended for routine screening. Placement of levonorgestrel-releasing intra-uterine system after hysteroscopy may be an effective intervention for patients with a high risk of giant polyps. Cluster of Differentiation 10, Estrogen receptor, Progesterone receptor, and nuclear antigen may be predictors for prognosis and selection of individualized treatment program.
