Immunohistological determination of oestrogen receptor, progesterone receptor, and intermediate filaments in Leydig cell tumours, Leydig cell hyperplasia, and normal Leydig cells of the human testis.

Testicular Leydig cell tumours are able to produce oestrogens and can be induced by exogeneous oestrogen administration. Oestrogen and progesterone receptors, cytokeratin, vimentin, and proliferative activity were determined immunohistologically in human testes in six Leydig cell tumours, 14 cases of Leydig cell hyperplasia, and 13 cases with normal Leydig cells. While both steroid receptors were detected in about 70 per cent of the tumour cells in cryostat sections, no reaction was observed in normal Leydig cells. This supports the hypothesis of an enhanced receptor state in a Leydig cell subpopulation as a basic pathophysiological factor in the development of Leydig cell tumours. On cryostat sections, all tumours co-express cytokeratin and vimentin. Neither the receptors nor the intermediate filaments could be detected reliably in paraffin sections. The low proliferative activity of Leydig cell tumours corresponds to their benign clinical course.