Struma ovarii: two case reports of a rare teratoma of the ovary

Struma ovarii is an extremely rare type of ovarian teratoma distinguished by the unusual presence of thyroid tissue. It is usually a benign condition; however, malignant transformation is sometimes detected. The diagnosis relies on histopathological examination and is infrequently made on routine investigations. We report two cases of struma ovarii: one benign and the other malignant. The first case involved a 27-year-old woman who underwent a right ovarian cystectomy for an incidental ultrasonographic finding of a solid right adnexal mass. The diagnosis of a benign struma was made after histopathological study. The second case involved a 68-year-old woman who underwent a right salpingo-oophorectomy for a right ovarian bulky mass and the histopathological diagnosis was consistent with that of a malignant struma. We examine the challenges involved in the diagnosis and management of this rare entity.