A case of virilizing brenner tumor in a postmenopausal woman with stromal androgenic activity

Although there are several reports of Brenner tumor showing estrogen activities, it is an extremely rare cause of androgen excess leading to virilism, and the source or mechanism of its androgen production is also unknown at present. A 74-year-old woman presented with lower abdominal pain and increased facial hair growth of 6-month duration. Bilateral ovarian tumors were detected, and her serum testosterone (1.7 ng/mL) and estradiol (75 pg/mL) levels were elevated. Bilateral salpingo-oophorectomy was performed. The ovarian tumors were diagnosed as benign Brenner tumor associated with fibrothecoma-like and luteinized stromal cells. Postoperatively, the serum testosterone and estradiol levels decreased. Immunohistochemically, fibrothecoma-like stromal cells were positive for cytochrome P-450 aromatase, which catalyzes the conversion from androgen to estrogen, and negative for c-Jun protein, which has recently reported to attenuate estrogen biosynthesis by directly down-regulating transcription of the aromatase gene. On the other hand, luteinized stromal cells were negative for cytochrome P-450 aromatase and positive for c-Jun protein. It is suggested that androgen is produced mainly in the luteinized stromal cells, because androgen is not converted to estrogen caused by suppression of aromatase biosynthesis by c-Jun.