Pilocytic astrocytoma arising in a dermoid cyst of the ovary: a case presentation

Collision Glial Neoplasms Arising in an Ovarian Mature Cystic Teratoma: A Rare Event

Germ cell neoplasms represent around 20% of all ovarian tumors. They most frequently affect children and young adults. Mature cystic teratoma is a common benign ovarian neoplasm comprising about 95% and is made up of all three germ cell embryonic layers. By definition, mature cystic teratoma may be derived from any of the three germ cell lines. On the other hand, immature teratomas contain primitive neuroepithelial elements. However, it is quite uncommon in the English literature to have a neuroepithelial glial neoplasm arising in a mature cystic teratoma of an adolescent. Interestingly enough, all published cases described a single type of glial neoplasm arising in mature ovarian teratoma. Herein, the authors discuss a unique case of concomitant occurrence of two different glial neoplasms, namely pilocytic astrocytoma and subependymoma arising in an ovarian mature cystic teratoma. To the best of our knowledge, this is the first reported case with such a distinctive histopathologic finding.

Germ Cell Tumors of the Female Genital Tract

Ovarian germ cell tumors are a histologically diverse group of neoplasms with a common origin in the primitive germ cell. The vast majority are represented by mature cystic teratoma. In the minority are malignant germ cell tumors including immature teratoma, dysgerminoma, yolk sac tumor, embryonal cell carcinoma, and choriocarcinoma. This article reviews the histologic and immunohistochemical features of the most common ovarian germ cell tumors. The differential diagnoses for each are discussed.

Oligodendroglioma arising in the glial component of ovarian teratomas: a series of six cases and review of literature

AIMS

To report the exceedingly rare occurrence of oligodendroglioma in the glial component of ovarian teratomas.

METHODS

Six cases of oligodendrogliomas arising in the glial component of ovarian teratomas were studied and the literature was reviewed. Immunohistochemistry was performed by the Flex technique.

RESULTS

The ages of the patients ranged from 12 to 28 years (mean 21 years). Four tumours were located in the right and one in the left ovary. The size of the ovarian cysts ranged from 7 cm to 29 cm (mean 19.6 cm). Four cases arose in immature and two cases in mature teratomas. In all cases, oligodendroglioma was WHO grade II. On immunohistochemistry, glial fibrillary acidic protein stain was positive in all cases. The Mib 1 (Ki 67) proliferative index was low and the tumour cells were negative for synaptophysin. Follow-up was available in five patients and ranged from 1 to 42 months. Two patients died of disease after 1 and 36 months of diagnosis, respectively. In both these cases oligodendroglioma arose in an immature teratoma. The remaining three patients are alive with a follow-up of 4-42 months.

CONCLUSIONS

Oligodendroglioma arising in the glial component of ovarian teratomas is exceedingly rare. Ovarian teratomas should be extensively sampled and carefully evaluated to rule out the possibility of a glial tumour. This is the single and largest series of oligodendrogliomas arising in ovarian teratomas. The prognosis is good for oligodendrogliomas arising in mature teratomas compared with those arising in immature teratomas, although long-term follow-up is needed to determine the exact behaviour.