Primary and recurrent serous borderline tumors during pregnancy: a case report and literature review.

The diagnosis and management of borderline ovarian tumors during pregnancy are still not standardized, because these tumors are rarely encountered. We report the case of a 27-year-old pregnant woman who presented with an ovarian mass in her first trimester. Magnetic resonance imaging revealed a multilocular cystic component with papillary lesions in the background of endometriosis, suggesting a seromucinous borderline tumor or ovarian cancer. A right salpingo-oophorectomy and partial omentectomy were performed at 7 weeks of gestation. Pathological examination demonstrated a serous borderline tumor. The subsequent pregnancy course was uneventful, and she gave birth to a healthy baby at 39 weeks of gestation. She wanted to retain fertility, and close follow-up was performed. Four years later, she became pregnant, and a lesion suggesting recurrence in the left ovary was detected. An abdominal left ovarian cystectomy was performed at 13 weeks of gestation, which demonstrated recurrence of the serous borderline tumor. She gave birth to a healthy baby at 39 weeks of gestation. Two months after delivery, she underwent total abdominal hysterectomy with left salpingo-oophorectomy, which revealed no malignant findings. We also reviewed 10 reports that included 58 cases of borderline ovarian tumors diagnosed during pregnancy. The borderline ovarian tumors diagnosed during pregnancy exhibited different characteristics according to each subtype, suggesting the importance of diagnosing borderline ovarian tumor subtypes preoperatively. © The Japan Society of Clinical Oncology 2021.