Intermediate filaments cytokeratin and vimentin in ovarian sex cord-stromal tumours with correlative studies in adult and fetal ovaries.

The expression of the intermediate filaments cytokeratin and vimentin were studied immunohistochemically in a series of ovarian sex cord-stromal tumours (26 adult and juvenile granulosa cell tumours, 11 thecomas, six fibromas, three Sertoli-Leydig cell tumours and 1 sex cord tumour with annular tubules). Contrary to previous reports, granulosa cell tumours expressed cytokeratins as well as vimentin. Thecomas and fibromas expressed vimentin only. In Sertoli-Leydig cell tumours and the sex cord tumour with annular tubules, both cytokeratins and vimentin were detected. Correlative studies in adult ovaries showed that patterns of expression in non-neoplastic granulosa, thecal and stromal cells correspond to their neoplastic counterparts. Investigation of fetal ovaries demonstrated that these patterns of intermediate filament expression exist from relatively early stages of development. Ovarian surface epithelium and rete ovarii, like granulosa cells, co-expressed cytokeratin and vimentin. The demonstration of cytokeratins in granulosa cells and the reported presence of desmosomes and tonofilaments, suggests the epithelial nature of these cells although not clarifying their histogenesis. The presence of both these intermediate filaments in granulosa and Sertoli-Leydig cell tumours as well as in some ovarian carcinomas which may mimic them, limits their value in differential diagnosis between these tumour groups.