Sertoli cell tumors are a common type of testicular tumor. They can be functional and may secrete estrogen. This excess hormone production leads to hyperestrogenism and feminization.

The Sertoli cell tumor at left is clearly well-demarcated from the surrounding testicular parenchyma. There is a clear delineation between the pink tumor and the light brown tissue of the testis. Some tumors infiltrate the surrounding tissue or are more indistinct, but this one is well-demarcated.