Differentiation potential of ovarian dysgerminoma: an immunohistochemical study of 15 cases.

An immunohistochemical study of 15 ovarian formalin-fixed, paraffin-embedded dysgerminomas showed positive staining of tumor cells for vimentin in all cases. Ten dysgerminomas stained for cytokeratin 18. Desmin positivity of single tumor cells was detected in four dysgerminomas. Glial fibrillary acidic protein was present in two tumors. Prominent human beta chorionic gonadotropin staining was seen in one tumor. S-100 protein was found in two and carcinoembryonic antigen in one of the dysgerminomas. Placental alkaline phosphatase was present in 12 of the 15 tumors studied. The heterogeneity of the cytoskeletal profile and of other markers showed some similarities to our previously published results on testicular seminomas. Thus, in contrast to previous concepts, dysgerminoma, as is the case with its testicular counterpart the seminoma, appears to be capable of further differentiation, albeit at a primitive level. Our observations also may help to elucidate the relationship between dysgerminoma and other nondysgerminomatous ovarian germ cell tumors, and may be of help in the differential diagnosis with poorly differentiated carcinoma, ovarian lymphoma, or other germ cell tumors.