Ependymoma in ovarian monodermal teratoma: A case study

Germ cell tumors comprise about 20% of all ovarian tumors and most of which are mature cystic teratomas. Monodermal teratomas are germ cell tumors derived from a single germ layer. A 33-year-old-woman revealed to the gynecology outpatient clinic with pelvic pain which is persisting for one month. The physical examination and ultrasounographic evaluation revealed a pelvic mass. Thus, laparotomy was performed. As a result of the frozen section analysis, the mass in the left ovary was diagnosed as malignant. The patient underwent left salpingo-oophorectomy and subsequent right ovarian wedge biopsy, appendectomy, total omentectomy and pelvic lymph node dissection. Dissection revealed a biloculated and partially cystic appearance. Microscopic examination indicated mature brain tissue in addition to neural tissues with perivascular pseudorosettes. According to the immunohistochemical and microscopic findings, the case was reported as ependymoma developed in a monodermal teratoma with neuroectodermal differentiation. Although mature cystic teratomas are the most common ovarian tumors ,malignant transformation is a rare complication occurring in approximately 2% of cases. The most common type of malignant transformation is to squamous cell carcinoma. Because of ependymoma development in ovarian monodermal teratoma is extremely rare in the literature, it should be considered in clinical and pathological examination.