Benign Struma Ovarii Presenting as a Large Multicytic Ovarian Mass: Case Report

Abstract Background Struma ovarii is a very rare form of ovarian teratoma with thyroid tissue present in the ovarian mass. A struma ovarii is categorised based on 50% or more of solid tissue being thyroid tissues. This particular entity can be an adult teratoma with distinct diagnostic challenges by virtue of its peculiar features, including thyroid hormone production. The tentative diagnosis is examined in a perimenopausal woman, with long-standing lower abdominal distention. Case Presentation: A 42-year-old woman, with a parity of 4 presented with a two-year history of intermittent episodes of dull lower abdominal pain associated with a feeling of a mass descending across her abdomen. This was associated with episodes of nausea, occasional vomiting, and dyspareunia for about five months. The patient also had irregular heavy menstrual periods for a similar duration. History did not reveal any signs of hyperthyroidism, Abnormal Uterine bleeding nor urinary tract symptoms. On physical examination, a firm, immobile, well-defined suprapubic mass was noted. Evaluation with abdominopelvic ultrasound showed a large, complex left adnexal cystic lesion with multiple septations. The patient was taken up for an exploratory laparotomy. Intraoperatively, a large, tortuous, multi cystic mass and highly vascularized, arising from the left ovary was found, and a left salpingo-oophorectomy was performed. Histopathological examination revealed a multicystic ovary with solid areas that contained seromucinous fluid and hemorrhage. Histological verification was made by the demonstration of ovarian tissue containing 80–90% benign thyroid follicles of varied sizes lined with cuboidal epithelium; with foci of calcification; and no evidence of malignancy. The patient made an uneventful postoperative recovery Conclusion Struma ovarii is tough to diagnose because it mimics so many other conditions and rarely causes thyroid symptoms. In women of reproductive age who have complex ovarian masses, it’s worth keeping in mind, even if their thyroid tests are normal. The only way to be sure is to look at the tissue under a microscope after surgery, which, for benign cases, also solves the problem.