[Struma ovarii or malignant ovarian goiter. A case].

BACKGROUND: We report a case of follicular struma ovarii observed in an ovary teratoma without metastatic dissemination.

CASE REPORT: A right ovarian tumor was discovered at ultrasound examination in a 31-year-old woman complaining of low abdominal pain. The patient underwent laparoscopic exploration and a 4-cm cystic mass of the right ovary was removed. Microscopic examination showed a malignant struma ovarii of the follicular type with vascular space invasion; other teratomous elements were identified. Immunohistochemical staining for thyroglobulin confirmed the nature of the tumor. The patient was treated by complete right ovariectomy followed by total thyroidectomy and administration of radioactive iodine (99 mCi I-131). Repeat I-131 body scan performed at 6 months was normal.

DISCUSSION: Struma ovarii is a rare type of ovarian teratoma, consisting mainly of thyroid tissue. The incidence of malignant struma ovarii is below 1% and fewer than two dozen cases with distant metastases have been reported. The major problem associated with struma ovarii has been the establishment of criteria for malignancy.