CONCLUSION:
Malignant transformation of mature cystic teratoma into undifferentiated carcinoma is rare. Post-menopausal women presenting with giant tumors must raise suspicion for malignancy since preoperative diagnosis is often impossible. An intraoperative diagnosis aid in the diagnosis and determine the extent of surgical treatment. Immunohistochemistry can help differentiate the type of carcinoma, which can further determine the treatment and prognosis. There are no fixed guidelines for treating malignant transformation of MCTO; surgery followed by chemotherapy is usually the standard of treatment. Diagnosis in the early stages improves survival. Hence, early detection and proper evaluation of the type of carcinoma can affect survival.