Secondary Amenorrhea with Low Serum Luteinizing Hormone and Follicle-stimulating Hormone Caused by an Inhibin A- and Inhibin B-producing Granulosa Cell Tumor

SummaryObjectiveHere, we report a case of secondary amenorrhea with low serum luteinizing hormone and follicle-stimulating hormone levels due to an inhibin A- and inhibin B-producing granulosa cell tumor of the ovary.Case ReportA woman aged 26 with infertility, secondary amenorrhea and low levels of gonadotropin was referred to us as a case of hypothalamic amenorrhea. There was a mass measuring 56 × 41mm in her right adnexa. We were suspicious of malignancy and checked the tumor marker levels. Laboratory findings showed high levels of inhibin A and B. She underwent an exploratory laparotomy. Microscopic examination revealed an adult granulosa cell tumor. Eighteen days after excision, she had spontaneous menstruation with normal levels of follicle-stimulating hormone and luteinizing hormone.ConclusionA granulosa cell tumor secretes inhibin A and B, which suppress follicle-stimulating hormone and luteinizing hormone release through a central mechanism. This leads to amenorrhea, which can be misdiag-nosed as hypothalamic amenorrhea. Inhibin-producing ovarian tumors must be considered in the assessment of patients with apparent hypothalamic amenorrhea.