Thyroid-Type Carcinoma of Struma Ovarii (Report‪)‬

Struma ovarii is a monodermal variant of ovarian teratoma, which was initially described by Bottlin in 1888 and, later, by Pick in 1902 and 1903, who recognized that struma ovarii was composed of thyroid tissue. (1) Malignancy of struma ovarii is rare. The malignant struma ovarii was first described by Wetteland in 1956. (2) Since its initial description, struma ovarii, especially malignant struma ovarii, has elicited considerable interest because of its many unique features. (1) Upon review of the literature, papillary carcinoma and follicular carcinoma are the most frequent types of malignancy to occur in struma ovarii; other forms of thyroid carcinoma occur rarely. Most recently, Roth and Karseladze (3) described a new entity of follicular carcinoma, highly differentiated follicular carcinoma of ovarian origin (HDFCO), characterized by extraovarian dissemination of thyroid elements with an innocuous appearance that histologically resembles nonneoplastic thyroid tissue. In the literature, the term malignant struma ovarii has been used in 2 ways: struma ovarii with thyroid-type carcinoma; and struma ovarii that has metastasized. Regarding the occurrence of malignancy in struma ovarii, the literature is confusing because many of the cases reported as malignant struma ovarii have not been accurately classified, and no large series has been carefully documented. (1) Several cases reported as malignant struma ovarii in the older literature were actually examples of strumal or insular carcinoid. (4) Because of varying usage and the lack of a precise definition, it is recommended that the term malignant struma ovarii no longer be used for cases of malignancy that develop in struma ovarii, except in the generic sense. The term thyroid-type carcinoma originating (arising) in struma ovarii (specifying the type) is more appropriate. (1) CLINICAL FEATURES