MIXED MESODERMAL TUMOR OF THE OVARY - IMMUNOHISTOCHEMICAL STUDY WITH HISTOGENETIC CONSIDERATION

The clinical, histological and immunohistochemical features of three c ases of ovarian mixed mesodermal tumor (MMT) were examined. The epithe lial component was serous papillary cystadenocarcinoma in case 1 and 3 , and endometrioid adenocarcinoma in case 2. In case 1, undifferentiat ed adenocarcinoma was also seen. The mesenchymal component was fibrosa rcomatous and chondrosarcomatous in case 1 and 2. In case 3, only fibr osarcomatous area was seen. No endometriosis was observed. Immunohisto chemically, the epithelial component showed positivity for epithelial membrane antigen in all three cases. S-100 protein was positive in two cases with chondrosarcomatous differentiation. The fibrosarcomatous a rea showed positivity for vimentin in all three cases. However desmin, myosin and myoglobin were negative. The antibodies thought to be epit helial or mesenchymal markers unexpectedly reacted positively in some cells; for example, EMA was positive in fibrosarcomatous and chondrosa rcomatous cells. Therefore, it was speculated that because the undiffe rentiated tumor cells had a biphasic character, MMT might originate fr om immature multipotential cells of surface epithelium and subcapsular connective tissue of the ovary.