Synchronous bilateral primary ovarian cancer with right endometroid carcinoma and left high-grade serous carcinoma: a case report and literature review

Epithelial ovarian cancer is the most frequent gynecologic malignancy; it has a poor prognosis and often occurs bilaterally. Most cases of synchronous bilateral ovarian cancer (SBOC) are metastases from the other ovary, while bilateral primary ovarian cancer is rare. The patient was a 47-year-old Japanese woman with a complaint of abdominal pain for 1 month. Imaging results revealed bilateral ovarian tumors with suspicion of malignancy. The patient underwent a laparotomy with total hysterectomy, bilateral salpingo-oophorectomy, partial omentectomy, and resection of suspected dissemination in the peritoneum. Histopathological and immunohistochemical studies showed that the right ovarian tumor was an endometrioid carcinoma (G2) and had no association with endometriotic lesions. However, the left ovarian tumor was a high-grade serous carcinoma (HGSC). The final staging was stage 1 right endometrioid carcinoma and stage IIb left HGSC. Six courses of adjuvant chemotherapy with paclitaxel, docetaxel, and carboplatin were administered. The patient showed no signs of recurrence 24 months postoperatively. To the best of our knowledge, the combination of histological types in this case may be the first report of primary bilateral ovarian cancer. In SBOC, it is important to differentiate the subtypes of histology using immunostaining, in addition to morphopathology.