Origin of an Ovarian Steroid Cell Tumor Causing Isosexual Pseudoprecocious Puberty 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 neoplastic cells closely resemble adrenal cortical cells. Nevertheless, the true adrenal origin of such tumors has been difficult to demonstrate. Here we report 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 enzymes (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 were undetectable (