Malignant struma ovarii--a case report and review of the literature.

BACKGROUND: Struma ovarii is a rare monodermal ovarian teratoma composed predominantly of mature thyroid tissue. Of these cases, 5-8% are clinically hyperthyroid and 5-10% of these tumors are malignant.

CASE REPORT: A 53-year-old female presented with a 19 x 5 x 5 cm pelvic mass that was treated with bilateral salpingo-oophorectomy, pelvic and para-aortic lymph node sampling, omentectomy and appendectomy and staging for an ovarian tumor. There was no evidence of distant metastases or lymph node invasion. Re-evaluation of the patient after surgery revealed that she was clinically euthyroid and there was no thyroid malignancy. Histopathology revealed papillary thyroid carcinoma arising in struma ovarii (malignant struma ovarii).

CONCLUSION: Malignant struma ovarii is a very rare malignant ovarian teratoma. In young patients unilateral oophorectomy and complete surgical staging should be considered when the tumor is confined to the one ovary (stage Ia). Long-term follow-up for the detection of metastases or tumor recurrence by serial serum thyroglobulin and (131)I scan or positron emission tomography/computed tomography may be required in selected patients with this rare tumor.