RT Journal Article SR Electronic T1 Struma ovarii showing clinical characteristics of ovarian malignancy JF International Journal of Gynecologic Cancer JO Int J Gynecol Cancer FD BMJ Publishing Group Ltd SP 1156 OP 1159 DO 10.1136/ijgc-00009577-200511000-00027 VO 15 IS 6 A1 S. Y. RIM A1 S. M. KIM A1 H. S. CHOI YR 2005 UL http://ijgc.bmj.com/content/15/6/1156.abstract AB Struma ovarii is a rare form of ovarian neoplasm, composed entirely or predominantly of thyroid tissue and generally a benign germ cell tumor of the ovary. Ascites have been reported in approximately 15–20% of all cases. However, the combination of struma ovarii and elevated CA125 has rarely been reported. We experienced a rare case of a postmenopausal woman with benign struma ovarii associated with massive ascites, a complex pelvic mass. There was marked elevation of her CA125 level. The clinical impression was ovarian malignancy. Surgical excision of the ovarian mass induced immediate resolution of the ascites and a normalization of the serum CA125 level. No recurrence of the ascites or of the tumor has been observed during the 10-month follow-up. Struma ovarii can mimic ovarian malignancy clinically, particularly if complex and associated with ascites and an elevated CA125 level.