Testicular sex cord-stromal lesions: immunohistochemical analysis of cytokeratin, vimentin and steroidogenic enzymes.

We have studied immunolocalization of all steroidogenic enzyme involved in sex steroids biosynthesis, P-450 side chain cleavage (P-450scc), 3 beta hydroxy steroid dehydrogenase (3 beta-HSD), P-450 17 alpha hydroxylase (P-450(17 alpha)) and P-450 aromatase (P-450arom) and that of vimentin and cytokeratin in 14 cases of testicular sex cord-stromal tumours (6 Leydig cell tumours, 5 Sertoli cell tumours, 2 fibromas and 1 granulosa cell tumour) as well as 4 cases of hyperplasia (2 Leydig and 2 Sertoli). Leydig cell tumour expressed all four steroidogenic enzymes examined, indicating that this tumour can synthesize oestrogen from cholesterol. In 2 cases of Sertoli cell tumour, the tumour cells with clear cytoplasm and without Reinke's crystals expressed P-450ssc, 3 beta-HSD and P-450(17 alpha), suggesting the capability of androgen production in these tumour cells. Fibromas and granulosa cell tumour were negative for the enzymes examined. In immunohistochemistry of intermediate filaments, Leydig cell tumours demonstrated only vimentin. Sertoli cells in hyperplasia and non-neoplastic testis expressed only vimentin but Sertoli cell tumours expressed both cytokeratin and vimentin. Cytokeratin immunoreactivity was correlated with morphological epithelial differentiation in Sertoli cell tumour. These findings in testicular Sertoli cell tumour are considered to represent the multiple differentiation capacity of this neoplasm. Immunohistochemical study of steroidogenic enzymes and intermediate filaments provided new insight into neoplastic steroidogenesis and the differentiation capacity of testicular sex cord-stromal neoplasms.