Immune-mediated encephalitis and virilization in association with a mature cystic ovarian teratoma in an adolescent girl.

BACKGROUND

Mature cystic teratomas are the most common form of ovarian tumor in children and adolescents. These tumors are mostly benign and non-secreting. Virilization from an ovarian teratoma is exceptionally rare in pediatrics. Equally rare is the association of ovarian teratomas with auto-immune encephalitis.

METHODS

We describe the case of a 15-year-old girl with menstrual abnormalities and virilization, who had a past medical history of encephalitis of an unknown etiology 16 months prior to presentation.

RESULTS

Endocrine evaluation revealed an elevated serum testosterone and 17-hydroxy progesterone. A large left ovarian tumor was seen on a CT scan. Surgical excision revealed a mature cystic teratoma containing 6 liters of clear fluid with high androgen levels. Antibodies to the N-methyl-D-aspartate receptor of the hippocampus were detected in pre-operatively archived serum, but undetectable 6 months postoperatively. Immunohistochemistry studies on the tumor sections revealed that the antibodies in the patient's serum reacted with areas of the tumor expressing the N-methyl-D-aspartate receptor. Postoperatively, the patient's menstrual cycles became regular and her behavioral problems resolved. Her testosterone levels fell precipitously as well.

CONCLUSION

Both virilizing mature cystic teratomas and teratoma-associated encephalitis are extremely rare in the pediatric population. We report on the first instance of these 2 rare entities occurring in the same patient.