INTRODUCTION: Malignant struma ovarii is a rare ovarian neoplasm composed predominantly of mature thyroid tissue.
CASE REPORT: A right ovarian tumor was discovered at ultrasound examination in a 20-year-old woman. Complete right ovariectomy was done - histopathological examination revealed papillary thyroid carcinoma arising in struma ovarii (malignant struma ovarii). Patient underwent subsequent total thyroidectomy - the thyroid was found to be without any pathological lesions. After operations the patient received ablative radioiodine treatment (200 mCi 131I). An 131I posttherapeutic whole-body radioiodine scintigraphy was performed and showed uptake in bone metastases. L-thyroxine TSH suppresive doses followed radioiodine ablation and thyroglobulin level is monitored. Next doses of radioiodine has been scheduled.
DISCUSSION: Authors suggest that the management of malignant struma ovarii should be the same as differentiated thyroid cancer, so after surgical excision of ovarian neoplasm, we recommend thyroidectomy, radiotherapy with 131I and levothyroxine suppressive therapy. Long-term follow-up for the detection of metastases or tumor recurrence by serial serum thyroglobulin measurements and 131I scan may be required in patients with this rare tumor.