A rare case of synchronous bilateral ovarian cancer with combined clear cell and mucinous carcinomas and brain metastases.

Although ovarian cancer is generally unilateral, a few cases of bilateral ovarian cancer have been reported, most of which originate from metastases of unilateral ovarian cancer. However, synchronous primary bilateral ovarian cancer (SBOC), comprising two different histological types of ovarian cancer, is extremely rare, with limited reports on its clinical course and prognosis. Herein, we report the case of a 56-year-old postmenopausal Japanese woman with stage IVB SBOC with combined left ovarian clear cell and right ovarian mucinous carcinomas. The patient underwent surgery and received postoperative taxane/platinum-based chemotherapy, which temporarily reduced the tumor size. However, an increase in tumor size and brain metastases were subsequently identified. Treatment was accordingly discontinued, and the patient died of the disease 12 months after diagnosis. In this case report, we detail the clinical course of a case of SBOC. To the best of our knowledge, this is the first report of SBOC with combined histological types of clear cell and mucinous carcinomas, and it is also the first report of SBOC with the eventual discovery of brain metastases.