Mixed germ-cell malignancies of the ovary contain two or more elements of the lesions described above. In one series, the most common component of a mixed malignancy was dysgerminoma, which occurred in 80%, followed by EST in 70%, immature teratoma in 53%, choriocarcinoma in 20%, and embryonal carcinoma in 16%.,440 The most frequent combination was a dysgerminoma and an EST. The mixed lesion may secrete either AFP or hCG, or both or neither, depending on the components.

Because most of these lesions contain poorly differentiated elements, mixed germ-cell malignancies should be treated with combination chemotherapy, probably BEP or VBP. The serum marker, if positive initially, may become negative during chemotherapy, but this may reflect the regression of only a particular component of the mixed lesion. Therefore, in patients with advanced-stage mixed germ-cell malignancies, a second-look laparotomy may be useful to determine the response to therapy, unless the tumor was confined initially to the ovary.

The most important prognostic features are the size of the primary tumor and the relative amount of its most malignant component. In stage IA lesions smaller than 10 cm, survival is 100%. Tumors composed of less than one third EST, choriocarcinoma, or grade 3 immature teratoma also have an excellent prognosis, but it is less favorable when these components make up the majority of the mixed lesions.