Origin of an ovarian steroid cell tumor causing isosexual pseudoprecociouspuberty demonstrated by the expression of adrenal steroidogenic enzymes and adrenocorticotropin receptor

Ovarian steroid cell tumors are rare neoplasms composed of typical steroid hormone-secreting cells. Most ovarian steroid cell tumors, however, cannot be appropriately classified on a morphological basis, because the neoplasti c cells closely resemble adrenal cortical cells. Nevertheless, the true adr enal origin of such tumors has been difficult to demonstrate. Here we repor t a 3-yr-old girl with isosexual pseudoprecocious puberty due to an ovarian steroid tumor whose adrenal cell origin was determined by the presence of messenger ribonucleic acid (mRNA) of adrenal-specific steroidogenic P450 en zymes (P450c11 and P450c21) and ACTH receptor (ACTHR). Her height was +2.3 SD, and she had Tanner stage III breast development, Tanner stage II pubic hair, and a normal clitoris. Bone age was 5 yr. Basal gonadotropin levels w ere undetectable (<0.6 U/L for LH and <1.0 U/L for FSH) and remained undete ctable after stimulation with 100 mu g GnRH, iv. Basal serum testosterone a nd 17-hydroxyprogesterone levels were slightly elevated, whereas basal seru m androstenedione, estradiol, and dehydroepiandrosterone sulfate levels wer e clearly elevated. Pelvic ultrasound disclosed an enlarged uterus and an a dnexal multicystic mass in the right ovary, and pathological studies disclo sed an ovarian steroid cell tumor. To establish the cellular origin of the tumor we determined the presence of mRNA for P450c11, P450c21. and ACTHR in tumor tissue and normal adrenal and ovarian tissue. Detection of ACTHR, P4 50c21, and P450c11 mRNAs isoforms was achieved in tumoral and adrenal contr ol tissue, but not in the ovary control tissue. The RT-PCR products of P450 c11 from adrenal central tissue were composed by both Bg11-sensitive and -r esistant complementary DNAs, indicating the presence of both P450c11AS and P450c11 beta, whereas RT-PCR product from the tumor was resistant to Bg/I d igestion, indicating only the presence of P450c11 beta. We conclude that the histological origin of so-called adrenal rest tumor co uld be reliably determined by assessing the expression of specific genes in the tumor as P450c11 beta and P450c21. The use of these molecular tools wi ll allow a more precise classification of an important subset of the ovaria n steroid cell tumors and can help to identify ectopic adrenal tissue in ov ary and testis.