Struma Ovarii: A Rare Unpredictable Ovarian Teratoma Case Series and Review of Literature

Struma ovarii is a rare ovarian teratoma of monodermal variant constituting 1-4% of all benign ovarian teratoma. Any ovarian teratoma is called struma ovarii only when it consists of at least 50% thyroid tissue. Only about 8% of struma ovarii cases present with clinical and biochemical features of thyrotoxicosis which is presumed to be due to ectopic production of thyroid hormone and only 0.5 to 5% undergo malignant transformation. We report seven cases of varied clinical presentations of struma ovarii operated at a single centre over four years duration, from January 2014 to December 2017, and endeavor to define the clinical features of this neoplasm as regards to ultrasonographic findings, histological features and ideal management. The clinical presentation, laboratory findings and imaging of these patients are very diverse. Pathologic findings confirm the diagnosis. Due to its rarity, there is no consensus on the best management of Struma ovarii and each case must be individualised. A review of the literature finds that most authors recommend surgical treatment. For malignant struma ovarii, surgery should be followed by postoperative total-body scinti-scanning with 1131 to evaluate for residual disease. Many studies recommend adjunct thyroidectomy with 1131 therapy to be considered first line management following surgery.