Malignant Struma Ovarii: A Rare Manifestation of Ectopic Thyroid Cancer

Malignant struma ovarii (MSO) is a rare malignant teratoma of the ovary composed predominantly of malignant thyroid tissue, often resembling papillary or follicular thyroid carcinoma. We present a case of Stage 1A MSO, in remission 5 years post-treatment, alongside a review of the literature. The patient, who presented with right-sided abdominal pain, had imaging that revealed a right adnexal mass. Pathology confirmed papillary thyroid carcinoma (PTC) confined to the right ovary. Surveillance included computed tomography (CT) scans and transvaginal ultrasounds, all negative for recurrence at 5 years. A literature review underscores the importance of pathology in diagnosing MSO, with treatment dependent on tumor aggressiveness, metastasis, and fertility concerns. Surgery, sometimes combined with radioactive iodine ablation, is the primary treatment. High survival rates are reported regardless of treatment approach, but limited data hinder the standardized guidelines, highlighting the need for continued case reporting.