Background: Malignant Struma Ovarii is a rare ovarian neoplasm that is usually asymptomatic and infrequently diagnosed preoperatively. A few case studies have described associated thyrotoxicosis.
Case: A 46-year-old female presented for her annual gynecologic exam during which a pelvic mass was appreciated on physical examination. Patient was asymptomatic at presentation. A follow-up ultrasound confirmed the presence of a 16-cm mass in the right adnexa. Patient underwent a total abdominal hysterectomy with bilateral salpingo-oophorectomy. Histopathology revealed a mature cystic teratoma with features of Struma Ovarii, containing a single 5-mm focus of papillary cancer within the thyroid tissue. Patient subsequently had a thyroid scan that was normal with normal thyroid function. There was no evidence of metastasis.
Conclusion: Malignant Struma Ovarii is a very rare disease and there are various approaches to treatment based on staging. In our review, we found a higher rate of metastasis than previously reported. Recurrence was seen after an average period of 4 years. We recommend follow-up with surveillance thyroglobulin levels in cases of malignant Struma Ovarii for at least 10 years.