Expression of intermediate filaments in normal ovaries and ovarian epithelial, sex cord-stromal, and germinal tumors.

The presence of different types of intermediate filaments (IMF) was studied in normal ovarial tissue and in ovarian tumors. The coelomic epithelium contained both prekeratin and vimentin, but the graafian follicle cells and stromal cells contained only vimentin. In normal ovaries, desmin positivity was confined to the arterial walls. Tumors derived from surface epithelium, including Brenner tumors, expressed prekeratin in the epithelial cells, whereas sex cord-stromal tumors showed only vimentin-type IMF. Germinal tumors also showed only vimentin-type IMF, whereas differentiated teratomas expressed the IMF of the corresponding differentiation line, as recognized by light microscopy. Thus, the skin, skin appendages, and other epithelial components of dermoid cysts showed prekeratin; mesenchymal components showed vimentin (but smooth muscle cells, desmin), and glial-like areas showed glial fibrillary acidic protein. The results suggest that expression of IMF in ovarian tumors corresponds to the filament expression of the parental tissues and that the typing of IMF can be used in the differential diagnosis between ovarian tumors of different histogenesis.