Localization of S-100 protein in a Leydig and Sertoli cell tumour of testis

A Sertoli-Leydig cell tumour of testis presented some diagnostic difficulties. The tumour cells showed strong expression of S-100 antigen. Preliminary study of non-neoplastic testis suggests that Leydig cells and, to a lesser extent, Sertoli cells express S-100 antigen; its localization may be of value in the diagnosis of sex cord-stromal tumours of testis.