An adolescent with ovarian osteosarcoma arising in a cystic teratoma.

A 14-year-old girl had an abdominal mass with the characteristics of an ovarian germ cell tumor on computed tomography scan. The mass, arising from the left ovary, was completely resected and found to be osteosarcoma arising from a mature cystic teratoma. A metastatic lesion in the abdomen did not respond to 2 courses of cisplatin, doxorubicin, ifosfamide, and high-dose methotrexate, and was resected. Seven months after completion of chemotherapy, there were simultaneous local recurrence and lung metastases. Previously, 10 cases of ovarian osteosarcoma have been reported in the literature: 5 were primary osteosarcoma of the ovary, 4 were associated with teratomas, and 1 was part of a malignant mixed mesodermal tumor of the ovary. Of the 10, there are only 2 long-term survivors, both of whom were treated with adjuvant chemotherapy following complete resection.