Serous borderline ovarian tumor with functioning stroma in a postmenopausal woman: immunohistochemical analysis of steroidogenic pathway.

An epithelial ovarian tumor with estrogenic manifestations (vaginal bleeding, vaginal softening) was encountered in a 70-year-old woman. The preoperative serum levels of estrone, estradiol, and testosterone were elevated. A right ovarian serous papillary tumor of borderline malignancy was removed and found to have a cellular, focally luteinized stroma. Steroidogenic enzymes, including 3beta-hydroxysteroid dehydrogenase and P450 cytochromes specific for cholesterol side-chain cleavage (P450scc), 17alpha-hydroxylation (P45017alpha), and aromatization (P450arom), were immunohistochemically demonstrated in the stromal cells. Immunohistochemical evaluation of these enzymes suggest significant functional differences among the enzymatically-activated stromal cells. That only rare stromal cells were immunoreactive for P450arom suggests that most of the testosterone synthesized in the tumor is extragonadally converted to estrogen, resulting in tumor-associated estrinism.