Nodular Leydig cell hyperplasia in a boy with familial male-limited precocious puberty.

In boys with familial male-limited precocious puberty, an activating mutation of the luteinizing hormone receptor causes Leydig cell hyperplasia, resulting in excess testosterone production. There are no reports of Leydig cell masses in boys with familial male-limited precocious puberty. We describe a 10-year-old boy with familial male-limited precocious puberty who developed Leydig cell nodules.