Squamous cell carcinoma arising from a mature cystic teratoma of the ovary: Successful treatment with carboplatin, paclitaxel, and bevacizumab.

Ovarian mature cystic teratomas (MCT) are usually benign. However, squamous cell carcinoma (SCC) develops in 0.17-2% of MCT. Because of its low frequency, the optimal treatment for this disease is unclear. We present a case of SCC arising from MCT. Our patient was a 30-year-old nulliparous woman complaining of right lower abdominal pain, who was referred to our hospital for a pelvic solid mass with suspected malignant ovarian tumor. A diagnosis of SCC arising from MCT was suspected based on the elevation in SCC antigen and the imaging. After surgery to remove the tumor, the diagnosis was confirmed based on the pathology. Although the surgery by radical cytoreduction was optimal, the tumor showed early recurrence. Therefore, we administrated combination chemotherapy, consisting of carboplatin, paclitaxel, and bevacizumab, followed by maintenance therapy with bevacizumab. Response to the chemotherapy regimen was complete and the patient was alive with no evidence of recurrence for 45 months after starting the initial surgery. We discuss the clinical characteristics of the malignant transformation of MCT and the treatment of SCC arising from MCT.