Torsion of Metastatic Ovarian Tumor Originating From Sigmoid Colon Cancer

Metastasis of colorectal cancer (CRC) to the ovaries is relatively rare, and torsion of metastatic ovarian tumors is even rarer. Here, we report the case of a patient with CRC who developed torsion of ovarian metastases and underwent abdominal adnexectomy following chemotherapy with bevacizumab. A 51-year-old premenopausal woman presented with abdominal distension and was referred to our hospital after ultrasonography revealed abdominal tumors. Imaging showed bilateral ovarian masses (maximum diameters: right, 10 cm; left, 14 cm), subserosal leiomyomas, and a circumferential sigmoid colon tumor with peritoneal nodules and ascites. A colonoscopy confirmed moderately differentiated adenocarcinoma. The patient was diagnosed with stage IV sigmoid colon cancer, including ovarian metastasis, peritoneal metastases, and pleural effusion. The patient began chemotherapy with tegafur, gimeracil, oteracil potassium, oxaliplatin, and bevacizumab, resulting in a decrease in carbohydrate antigen 19-9 levels, though carcinoembryonic antigen levels increased. After the fourth chemotherapy cycle, the patient experienced sudden left-sided abdominal pain accompanied by nausea. Computed tomography revealed torsion of the left ovarian tumor (maximum diameter: 19 cm) with suspected hemorrhage. A drop in hemoglobin levels required a blood transfusion. Emergency laparotomy revealed a three-turn torsion of the left ovarian pedicle and an intra-tumoral hemorrhage. A bilateral adnexectomy was performed, and ovarian metastases from colon cancer were confirmed pathologically. Despite bevacizumab treatment, the patient's postoperative course was uneventful, and she was discharged on day 12. Chemotherapy was resumed. In patients with metastatic ovarian tumors who present with sudden abdominal pain, ovarian torsion should be considered in the differential diagnosis, even in the context of malignancy.