Precocious puberty caused by a testicular Leydig cell tumor

Testicular tumors are very rare in boys, approximately 1.5% of these are Leydig cell tumors. The authors present a 4.5 year-old boy with Leydig cell tumor of left testis, which was associated with increased sex steroid production that caused precocious puberty. These tumors are benign processes in prepubertal children. Beyond the rarity of this case the authors would like to report about its diagnostic difficulties and testis-sparing remove of it. The plasma 17-hydroxyprogesterone levels provide the distinction between congenital adrenal hyperplasia and Leydig cell tumor in patient with precocious puberty.