Malignant transformation arising from mature cystic teratoma of the ovary presenting as ovarian torsion: a case report and literature review

Objective: Ovarian torsion is an acute gynecological condition. Torsion is more likely to occur with benign rather than malignant tumors. Mature cystic teratoma of the ovary (MCTO) is frequent in women of reproductive age; however, the incidence of malignant transformation is approximately 2%. We report a case of malignant transformation of MCTO presenting as ovarian tumor torsion. Case report: A 51-year-old premenopausal woman was diagnosed with mature cystic teratoma in the left ovary 7 years ago. The patient visited our hospital because she had been experiencing of pain in left lower abdomen for the past two days. She was diagnosed with ovarian tumor torsion and underwent emergency surgery. The left ovarian tumor was twisted, and left salpingo-oophorectomy was performed. Histopathological examination revealed squamous cell carcinoma arising from the MCTO. We carefully followed the patients without performing staging laparotomy. On postoperative day 112, multiple lymph node metastases in the pelvic and para-aortic areas were found by positron-emission tomography and computed tomography. After referral to a university hospital, total hysterectomy, right salpingo-oophorectomy, partial omentectomy, and pelvic and paraaortic lymphadenectomy were performed. Metastases of squamous cell carcinoma were confirmed in the pelvic and para-aortic lymph nodes. Six courses of adjuvant chemotherapy with paclitaxel and carboplatin were given following radical surgery to prevent the recurrence of malignant transformation of MCTO. No recurrence of the disease has been observed during 2 years of follow-up. Conclusion: When physicians diagnose large ovarian tumor torsion cases, preoperative examinations should be performed, with the possibility of malignancy in mind.