Struma ovarii is a variant of mature cystic teratoma, with predominant thyroid element. Confirmatory diagnosis is by histopathology. It may mimic as ovarian malignancy in some. It may be associated with ascites in minority; even CA-125 has been found to be raised in some cases. We here report three cases - two operated for suspected ovarian malignancy in a postmenopausal female and one case operated for persistent benign ovarian cyst with raised CA-125 in a young female. In all histopathological diagnosis was a benign struma ovarii. It is difficult to diagnose these cases preoperatively as there are no specific clinical, radiological or serum markers for these rare tumors in the absence of thyroid biology abnormality. Most cases are diagnosed on histopathology. These benign tumors many times require extensive staging laparotomy for suspected ovarian malignancy in the absence of preoperative diagnosis. Prognosis is good for these tumors. Subtle radiological signs and a clinical suspicion can avoid extensive staging laprotomies in these patients.
Keywords: Monodermal ovarian teratoma; ovarian tumour; struma ovarii.