Ovarian mature cystic teratoma with malignant transformation and fistula formation into ascending colon: an unusual presentation of a dermoid cyst

Mature cystic teratoma of ovarian origin in postmenopausal female is an unusual differentiation. It is usually a straight forward diagnosis on imaging due to its fat and calcified contents. Here we present how a malignant transformation in mature cystic teratoma causing fistulous communication with bowel loops makes the diagnosis difficult even after using almost all the imaging modalities in the patient's workup and subsequently how it was managed surgically.