Diagnosis: Secondary Malignancy Arising in Mature Teratoma
• Squamous cell carcinoma is the most common malignancy to arise in mature cystic teratoma. It is difficult to diagnose preoperatively and has a poor prognosis.
• Patients with squamous cell carcinoma confined to the ovary have a far better prognosis than patients who present with extension of disease outside the ovary.
• Mature cystic teratomas are composed of tissue of all three germ cell layers—ectoderm, endoderm, and mesoderm. Malignancies can arise from any of these tissues. The transformation of mature teratoma to a malignant lesion is rare.
• Malignant lesions arising in mature cystic teratoma (from least to most common) include squamous cell carcinoma, adenocarcinoma, and melanoma. Lesions such as osteosarcoma and rhabdomyosarcoma have been reported more rarely.
• Cisplatin, which has been proven to be effective in patients with primary ovarian surface epithelial tumors, does not appear to be effective in patients with malignant transformation of mature cystic teratoma. This lack of effectiveness suggests that malignancies arising within mature cystic teratoma might be more aggressive than primary surface carcinomas.
