eng Science and Education Publishing American Journal of Medical Case Reports 2374-216X 2019-02-02 7 2 18 21 10.12691/ajmcr-7-2-1 AJMCR2019721 article Walid Mohamed Elnagar 1 Mai Mohammed Abdelwahab 2 Mohamed El-Bakry Lashin Maiabdelwahab@ymail.com 2 Obstetrics and Gynecology Department, Faculty of medicine, Zagazig University, Egypt Pathology Department, Faculty of medicine, Zagazig University, Egypt Struma ovarii represents a rare type of teratoma that is formed entirely of thyroid tissue. In most cases, these tumors are benign; however, malignant ones have also been reported. It is usually seen between 40 and 60 years and accounts for about 5 % of all cases of ovarian teratomas. Our case was a female patient, 40 years old, who was presented with vaginal bleeding, abdominal swelling and left sided pelvic mass for six months. Clinical examination and imaging techniques showed left ovarian neoplastic lesion and small amount of fluid in Douglas pouch. After laparoscopic excision, Histopathological examination was performed, it showed ovarian tissue, predominantly formed of mature thyroid tissue which are the key features of struma ovarii. In Conclusion: Struma ovarii is a rare ovarian tumor with variable clinical presentations, even can be malignant. Pre-operative diagnosis is usually difficult and confusing, so, it should be put in consideration in differential diagnosis of ovarian masses. http://pubs.sciepub.com/ajmcr/7/2/1/ajmcr-7-2-1.pdf Struma ovarii ovarian tumor thyroid laparoscopy benign