Origin of estrogen in isosexual precocious pseudopuberty due to a granulosa-theca cell tumor.

The purpose of the present study was to quantify the rates of production and to define the mechanism(s) or origin of sex steroid hormones in a 3 1/2-year-old girl with isosexual precocious pseudopuberty caused by a granulosa-theca cell tumor of the ovary. The results suggest that the hyperestrogenism occurs principally due to the secretion of estradiol-17beta synthesized de novo by the tumor, but that the tumor in vivo was also capable of aromatizing C19 plasma precursor hormones to estrogen.