Ovarian Myxoma in a Patient With Missed Abortion: A Diagnostic Dilemma

Ovarian myxoma is a rare benign mesenchymal tumor. It can be completely asymptomatic and is difficult to differentiate from other ovarian masses before surgery and final histopathology. We report a case of a 28-year-old primigravida who presented with a missed abortion at 11 weeks. Transvaginal ultrasonography incidentally showed a 6.5 × 5.7 cm complex solid-cystic right adnexal lesion in the pouch of Douglas. She was asymptomatic from the mass. After dilatation and evacuation for missed abortion, the patient was evaluated for an ovarian mass, and tumor markers were found negative. Repeat ultrasonography showed a heterogeneous lesion with coarse hyperechoic foci and posterior acoustic shadowing, suggesting a right ovarian teratoma. The patient was taken for laparotomy, wherein an 8 × 8 cm solid-cystic mass was found in the right ovary, and right ovarian cystectomy was done. Intraoperative scrape cytology came back negative for malignancy and showed columnar cells, squamous cells, and mature adipose tissue, which favored a benign cystic teratoma. Histopathology showed a thick collagenous capsule and stellate cells in abundant myxoid stroma without atypia. On immunohistochemistry, the tumor cells were positive for vimentin and negative for desmin and cytokeratin. The final diagnosis was ovarian myxoma. The postoperative course was uneventful, and the patient was discharged on postoperative day 5. There was no recurrence at one-year follow-up. This case shows that ovarian myxoma can mimic a mature cystic teratoma on imaging, gross examination, and cytology, and that the final diagnosis depends on histopathological examination (HPE) supported by immunohistochemistry.