[Malignant struma ovarii]. / Maligne struma ovarii.

A 46-year-old patient underwent exploratory laparotomy due to indications of ovarian malignancy. Bilateral salpingooophorectomy, total abdominal hysterectomy, omentectomy and lymphadenectomy were performed, but no residual tumour was seen. Histopathological examination of postoperative specimens revealed malignant struma ovarii, a very rare condition. The patient had a low risk of disease progression (T1>1cmN0M0). Management consisted of initial conservative follow-up, which included administration of thyroid-stimulating hormone (TSH) suppression therapy with levothyroxine.