Squamous cell carcinoma arising from mature cystic teratoma of the ovary with synchronous endometrial adenocarcinoma

Squamous cell carcinoma arising from a mature cystic teratoma of the ovary is a rare event representing only 1-2% of all mature cystic teratomas. Furthermore, the synchronous occurrence of a second malignancy in this setting is extremely rare. A 63-year-old woman presented with a pelvic mass which was diagnosed as a left ovarian mature cystic teratoma preoperatively by ultrasonography. The frozen section of the mass revealed a left ovarian mature cystic teratoma with a focus of squamous cell carcinoma. Subsequently surgical staging procedure for ovarian cancer was performed. The final pathologic diagnosis was squamous cell carcinoma in mature cystic teratoma of the ovary, and synchronous endometrial adenocarcinoma with a mixture of endometrioid and mucinous subtypes as an incidental finding. The combination of these two synchronous cancers is unique and to the best of our knowledge, this has not been previously reported in the English language literature.