Struma Ovarii with Papillary Thyroid Carcinoma and Metastasis to the Appendix: A Case Report and Literature Review

Struma ovarii is an infrequent type of teratoma arising from the ovary accounting for only 2% of all ovarian teratomas. These tumors have a benign biology with rare malignant transformation in about 3% of cases. The most common malignant transformation that arises from struma ovarii is papillary thyroid carcinoma. These neoplasms act in the same way as those arising from the thyroid gland, but due to the rarity of their occurrence there is still a debate over therapeutic options. We present a case of a 41-year-old Ethiopian Para IX woman presented with abdominal swelling for four years, accompanied by dull pain, satiety, and weight loss. Her vital signs were normal, and her abdominal examination revealed a large abdominopelvic mass. Her CA-125 was elevated, and her blood count, organ function tests, and serum electrolyte levels were normal. Abdominal ultrasound revealed a complex abdominopelvic mass with cystic and solid components, possibly ovarian teratoma. The patient underwent surgery, revealing a 14 by 10 cm right ovarian mass and a 3x3 cm appendiceal mass. Subsequently, total abdominal hysterectomy, bilateral salpingo-oophorectomy, total omentectomy, and appendectomy was done. Histopathologic evaluation revealed follicular proliferation of enlarged cells, with no papillary growth pattern. The case was diagnosed as malignant struma ovarii, a follicular variant of papillary thyroid carcinoma (FVPTC) with secondary deposits on the appendix. A complete thyroidectomy was done after the histopathology diagnosis. Malignant struma ovarii is rare making it challenging to treat since there are no established prognosticating histopathologic or clinical characteristics. The tumor size and metastasis determine the surgical treatment scope. Large-scale investigations are essential for prognostication and treatment options considering pathologic traits.