High-Grade Endometrioid Stromal Sarcoma of the Ovary: Malignant Transformation of Ovarian Mature Cystic Teratoma

We report an extremely rare case of ovarian high-grade endometrioid stromal sarcoma arising from a mature cystic teratoma with clinicopathologic features, and then we briefly review the pertinent literature. A 62-year-old nulliparous woman presented with lower abdominal pain that had begun 6 months earlier. Magnetic resonance imaging showed two adnexal masses with fat components, which suggested that they were mature cystic teratomas. The eccentric thick rim of the left mass showed irregular invasion of the uterus, which was suggestive of malignancy. Positron emission tomography/computed tomography demonstrated high fluorodeoxyglucose uptake in the corresponding area. The patient underwent debulking cytoreductive surgery. The diagnosis was of an International Federation of Obstetrics and Gynecology stage IIIC high-grade endometrioid stromal sarcoma arising from a mature cystic teratoma. After surgery, the patient received adjuvant chemotherapy with three courses of doxorubicin regimen. The cancer recurred 3 months after surgery, and the patient died of progressive disease. It might be helpful for clinicians to be aware of this rare disease and the poor prognosis when it is at an advanced stage.