Recurrent Malignant Struma Ovarii With Peritoneal Implants Following Prior Thyroid Carcinoma Treatment.

Struma ovarii (SO) is a rare form of ovarian teratoma predominantly composed of thyroid tissue. While most cases follow a benign course, some may exhibit malignant transformation or extra-ovarian spread. We present the case of a 43-year-old woman with a history of SO previously treated with right oophorectomy and systemic chemotherapy, along with a separate diagnosis of papillary thyroid carcinoma managed with total thyroidectomy and radioactive iodine ablation. She remained asymptomatic for several years until routine surveillance imaging revealed stable pelvic lesions. Surgical exploration via exploratory laparotomy and suboptimal cytoreduction was performed, leading to the resection of multiple peritoneal implants. Histopathology confirmed recurrence of malignant SO. Postoperative recovery was uneventful, and systemic therapy was deferred due to limited supporting evidence. This case highlights the importance of clinical suspicion, surveillance, and individualized surgical management for recurrent SO.