Seromucinous Cystadenoma and Benign Brenner Tumor: A Unique Collision Tumor of Ovary with Contralateral Benign Brenner Tumor.

Collision tumors of ovary are uncommon neoplasm characterized by the coexistence of two distinct tumors in ovary without histological mingling. Although various combinations have been reported, we report a new combination of seromucinous cystadenoma and benign Brenner tumor. Due to solid cystic nature of the lesion on radiology, they can be mistaken as malignant tumor. They are difficult to diagnose preoperatively. We report a case of 61-year-old female who presented with abdominal pain and hematuria. Magnetic resonance imaging suggested malignant lesion with possibility of serous cystadenocarcinoma or borderline malignant tumor. Histopathological examination of radical hysterectomy revealed collision tumor of right ovary composed of seromucinous cystadenoma and benign Brenner tumor with contralateral benign Brenner in the left ovary.