Oligodendroglioma Arising in Mature Cystic Teratoma

Background. Development of neuroepithelial tumors from mature cystic teratoma is very rare. We present a case of oligodendroglioma developing inside mature cystic teratoma. Case. Eighteen-years-old female, right adnexal mass with solid and cystic areas was detected. Sections showed all three germ layers. Also, a tumoral lesion was observed in a glial fibrillary matrix. Tumor was composed of monotonous, uniform cells which have oval-round nucleus, perinuclear halo, and indistinct cytoplasm. GFAP, EGFR, P53 were positive. Conclusions. We diagnosed oligodendroglioma arising from mature cystic teratoma. There was no recurrence at the end of 13 months followup. The number of cases which have been reported in the literature is only a few. 1. Introduction Mature cystic teratoma is the most common neoplasia of the ovary and it originates from all three germ layers (endoderm, mesoderm, and ektoderm). Ovarian teratomas account for 25% of all ovarian tumors [1]. Malignancies can develop from teratomas in the elderly, especially after the fifth decade. The most common malignancy originating from mature cystic teratoma is squamous cell carcinoma [2]. Additionally, adenocarcinoma, undifferentiated carcinoma, sarcoma, papillary carcinoma, and malignant melanoma can also develop [3]. But the development of neuroepithelial tumors is very rare. We present a case of oligodendroglioma developing inside mature cystic teratoma. 2. Case Report An eighteen-year-old female was admitted to our hospital with abdominal pain. On physical examination, on the right side of the abdomen a palpable mass was detected. Ultrasonography showed right adnexal mass with solid and cystic areas inside. After laparotomy and oophorectomy, pathological examination was performed. 2.1. Gross Evaluation Oophorectomy material had smooth surface and consisted of solid and cystic areas. On the cut surface mature adipose tissue, bone, cartilage, and hair and, in an area of about 6？cm soft, gray-pink, solid-microcystic lesion were observed. 2.2. Microscopic Evaluation In many sections tissues belonging to all three germ layers (adipose tissue, cartilage, bone, choroid plexus, nerve tissue, mucinous epithelium, etc.) were seen (Figures 1 and 2). Figure 1: Tumoral lesion inside mature cystic teratoma with glial fibrillary matrix. Figure 2: The sections showing a monotonous population of round, uniform cells with a hyperchromatic nucleus and perinuclear halo. Also, an area of about 6？cm tumoral lesion was observed in a glial fibrillary matrix. Tumor was composed of monotonous, uniform cells which have