Pseudo-precocious puberty caused by bilateral idiopathic testicular hyperplasia

A boy aged two years presenting with advanced development of the genitalia, but with prepubertal testes, and accelerated growth is described. Investigation indicated pseudo-precocious puberty, due to idiopathic interstitial cell hyperplasia. Difficulties in interpretation of the hormonal studies were encountered due to an aberrant left testicular vein. This rare condition which has been called Testotoxicosis is probably due to an inborn error of metabolism not yet identified.