Dedifferentiated chondrosarcoma arising in a mature cystic teratoma of the ovary: a case report and review of the literature.

Malignant transformation of a mature cystic teratoma of the ovary is rare, occurring in approximately 2% of all cases. The most common malignancy arising in mature cystic teratoma is squamous cell carcinoma. Much less frequently, the malignant transformation is represented by sarcomas. Dedifferentiated chondrosarcoma usually develops in bone. There has been no case of a dedifferentiated chondrosarcoma arising in mature cystic teratoma of the ovary since the establishment of this diagnostic entity. This is a report of a definitive dedifferentiated chondrosarcoma arising in a mature cystic teratoma of the ovary, presenting clinicopathologic features.