Leydig cell tumor with gynecomastia. Report of a case with electron microscopy.

A case of Leydig cell tumor is reported and discussed. The tumor, 1.5 cm in diameter, was located in the capsule of the right testis. Gynecomastia present for 3 months was almost absent 4 months postoperatively. Preoperative hormone analysis revealed a low concentration of serum testosterone, which was normalized 1 week postoperatively. In electron microscopic examination, several intracytoplasmic microbody-like structures and 'tigroid' mitochondria were noted. These findings are similar to the three earlier descriptions of Leydig cell tumors.