Immunohistochemical study of a case of malignant müllerian mixed tumor in comparison with the activity of normal uterine tissue.

A case of malignant Müllerian mixed tumor of the uterus, exhibiting a histology of heterologous osteosarcomatous differentiation, is presented. Special emphasis is placed on the characteristic immunohistochemical reactivity of the tumor tissue in comparison with that of normal uterine tissue in the proliferative phase. Keratin, cytokeratin, epithelial membrane antigen (EMA), carcinoembryonic antigen (CEA), and human chorionic gonadotropin (HCG) were found only in the carcinomatous element. However, neuron specific enolase (NSE), S-100 protein (S 100) and vimentin were identified in almost all tumor tissue elements. Desmin and actin were not stained in any elements. Myoglobin was only detected weakly in the squamous carcinomatous element. Undifferentiated cell element, composed of small, round, spindle, or polygonal cells showed positive reactions to NSE and S 100, but not to any other antibodies. As compared to the reactivities of the normal proliferative endometrium, the glandular epithelial cells were positive with NSE, S 100, vimentin and CEA, but the stromal cells were only positive with vimentin. Such a multitudinous and concomitant expression of antigenicity to the different tumor elements indicates a close relationship to its mesodermal Müllerian origin, and NSE, S 100 and vimentin might be most adequate indicators of these types of tumors.