A sex cord-stromal tumor of the testis or the ovary. It is characterized by the presence of Sertoli cells forming tubules. Leydig cells are rare or absent. It may be associated with Peutz-Jeghers syndrome. In males, the presenting symptom is a slow growing testicular mass. Most cases follow a benign clinical course. In females it may present with estrogenic or androgenic manifestations. The vast majority of cases have a benign clinical course.