Malignant transformation of ovarian mature cystic teratoma in a postmenopausal woman presented as acute abdomen.

Malignant transformation of mature cystic teratomas is uncommon but present in clinical practice. Especially in postmenopausal women, the clinical manifestation of a mature teratoma with undiagnosed malignant transformation as acute abdomen is extremely rare. In these cases, total hysterectomy with bilateral salpingo-oophorectomy is the treatment choice since the chance of malignancy is high. The prognosis is good if the cyst is not ruptured, is completely excised and the cancer does not extend beyond the capsule. In any other case, the prognosis is unfavorable since recurrence is common and the tumor is chemoresistant.