ABSTRACT
We experienced a boy manifesting sexual precocity with unilateral testicular tumor, who was finally diagnosed as CAH with 21-hydroxylase deficiency. Initial laboratory findings were compatible with peripheral precocious puberty. Ultrasonogram for testes showed heterogenous high echoic mass in the right testicle. Radical orchiectomy was performed and its pathology revealed benign Leydig cell tumor without Reinke crystal. But, testosterone was not decreased after 1 month of surgery. Second laboratory exam revealed increased DHEA-S and 17-hydroxyprogesterone. Finally, this case was recognized as CAH(simple virilizing type) with unilateral testicular adrenal rest tumor. In conclusion, CAH should always be considered during etiologic study for the male sexulal precocity even with unilateral testicular tumor.