Pseudo-isolated FSH deficiency caused by an inhibin B-secreting granulosa cell tumour: case report

Serum FSH as a Useful Marker for the Differential Diagnosis of Ovarian Granulosa Cell Tumors

Background: We evaluated whether the serum hormone levels are useful in the differential diagnosis of granulosa cell tumors (GCTs), regardless of menopausal status. Methods: Serum levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone, estradiol, and progesterone were measured preoperatively in all patients (n = 471) who underwent surgery for ovarian tumors at Chiba University Hospital between 2009 and 2021. These were compared in two groups, a GCT group (n = 13) and a group with other histological types (non-GCT) (n = 458). Results: The GCT group had significantly lower serum LH and FSH (p = 0.03 and p < 0.001, respectively) and significantly higher testosterone, estradiol, and progesterone (p < 0.001, p < 0.001, and p = 0.045, respectively) than the non-GCT group. Multivariate analysis revealed that serum FSH and estradiol were significantly associated with GCT (FSH, odds ratio (OR) = 0.0046, 95% confidence interval (CI) = 0.0026−0.22, p = 0.004; estradiol, OR = 0.98, 95% CI = 0.96−0.998, p = 0.046). Receiver-operating characteristic curve analysis for GCTs showed that the area under the curve of serum FSH was 0.99, with a sensitivity of 100% and a specificity of 98%, when the cutoff level was set at 2.0 IU/L. Conclusions: Preoperative serum FSH level is an extremely useful marker for differentiating GCTs from all ovarian tumors.

Secondary Amenorrhea and Infertility Due to an Inhibin B Producing Granulosa Cell Tumor of the Ovary. A Rare Case Report and Literature Review

Granulosa cell tumor of the ovary (GCT) is a rare ovarian tumor with nonspecific symptoms. Studies reported that GCT are usually secreting estrogens and inhibins, especially inhibin B. It is considered that, in premenopausal women, irregular menses or secondary amenorrhea may be an early symptom of GCT and, in postmenopausal women, the most common manifestation is vaginal bleeding. Additionally, endometrial abnormalities can be associated due to estrogenic secretion. At reproductive age, high levels of inhibin, lead to low levels of FSH and secondary amenorrhea causing infertility. At times, increased levels of LH in women with GCT are observed and the pathogenesis is still unclear. Therefore, inhibin B level can differentiate GCT from other causes of secondary amenorrhea. We report the case of a 26-year-old nulliparous, women who presented in our clinic with secondary infertility lasting longer than 2 years, secondary amenorrhea, polycystic ovarian syndrome, and suspicion of right ovarian endometrioma on CT scan. The ultrasound examination revealed that the right ovary was transformed in an anechoic mass with increased peripheral vascularity having a volume of 10 cm³. This patient had high serum levels of inhibin B and LH but normal levels of FSH and estradiol. The preliminary diagnosis of granulosa cell tumor of the ovary was made. After counseling, the informed consent for treatment was obtained and the patient agreed to undergo surgery. An uneventful laparoscopy was performed with right oophorectomy and multiple peritoneal sampling. The histological diagnosis confirmed adult GCT limited to right ovary, with negative peritoneal biopsies (FIGO IA). After surgery the patient recovered fully and had normal menstrual cycles with normal serum levels of hormones. Two months later she conceived spontaneously and had an uneventful pregnancy. In conclusion, for cases with secondary amenorrhea, the evaluation of inhibin B level is essential. Elevated inhibin B level may be a sign for the presence of an unsuspected tumor. With early diagnosis and treatment, the prognosis is generally good and the fertility may be preserved, especially in young patients with GCT.

Distal Enhancer Potentiates Activin- and GnRH-Induced Transcription of FSHB

FSH is critical for fertility. Transcription of FSHB, the gene encoding the beta subunit, is rate-limiting in FSH production and is regulated by both GnRH and activin. Activin signals through SMAD transcription factors. Although the mechanisms and importance of activin signaling in mouse Fshb transcription are well-established, activin regulation of human FSHB is less well understood. We previously reported a novel enhancer of FSHB that contains a fertility-associated single nucleotide polymorphism (rs10031006) and requires a region resembling a full (8 base-pair) SMAD binding element (SBE). Here, we investigated the role of the putative SBE within the enhancer in activin and GnRH regulation of FSHB. In mouse gonadotrope-derived LβT2 cells, the upstream enhancer potentiated activin induction of both the human and mouse FSHB proximal promoters and conferred activin responsiveness to a minimal promoter. Activin induction of the enhancer required the SBE and was blocked by the inhibitory SMAD7, confirming involvement of the classical SMAD signaling pathway. GnRH induction of FSHB was also potentiated by the enhancer and dependent on the SBE, consistent with known activin/GnRH synergy regulating FSHB transcription. In DNA pull-down, the enhancer SBE bound SMAD4, and chromatin immunoprecipitation demonstrated SMAD4 enrichment at the enhancer in native chromatin. Combined activin/GnRH treatment elevated levels of the active transcriptional histone marker, histone 3 lysine 27 acetylation, at the enhancer. Overall, this study indicates that the enhancer is directly targeted by activin signaling and identifies a novel, evolutionarily conserved mechanism by which activin and GnRH can regulate FSHB transcription.

Inhibin-B secretion and FSH isoform distribution may play an integral part of follicular selection in the natural menstrual cycle

The aim of the present paper is to expand the concept on how follicular selection takes place in the follicular phase of the natural menstrual cycle. It is suggested that inhibin-B exerts a more intimate role in this process than previously understood. Inhibin-B shows a peak in the circulation around cycle day 7, simultaneous with selection of the dominant follicle, whereas levels of estradiol and inhibin-A only start to increase a few days later suggesting that inhibin-B is mainly responsible for downregulating pituitary FSH release. New data now demonstrate that the circulatory peak of inhibin-B is reflected by peak production of inhibin-B, in contrast to inhibin-A, in the selected follicle with a diameter of 10-12 mm, where concentrations are one thousand times higher than in the circulation. This high inhibin-B concentration also exerts paracrine effects, stimulating theca cell androgen production in concert with LH. New data now suggest that in the corresponding granulosa cells androgens upregulate FSH receptor (FSHR) and LH receptor (LHR) mRNA expression, which in turn stimulate CYP19a mRNA expression providing the follicles which most effectively undertake these processes with the best chance of becoming selected. Inhibin-B production is stimulated by FSH and it appears that the acidic isoforms of FSH induce inhibin-B secretion most efficiently thereby, for the first time, placing the changing FSH isoform profile during the follicular phase in a physiological context. Collectively, it appears that inhibin-B is an integral part of follicular selection in the normal menstrual cycle, exerting both endocrine and paracrine effects and facilitating continued growth of the selected follicle.

Mechanisms of activin-stimulated FSH synthesis: the story of a pig and a FOX

Activins were discovered and, in fact, named more than a quarter century ago based on their abilities to stimulate pituitary follicle-stimulating hormone (FSH) synthesis and secretion. However, it is only in the last decade that we have finally come to understand their underlying mechanisms of action in gonadotroph cells. In this minireview, we chronicle the research that led to the recent discovery of forkhead box L2 (FOXL2) as an essential mediator of activin-regulated FSH beta subunit (Fshb) transcription in vitro and in vivo.

Isolated FSH deficiency revealing a granulosa cell tumor

We report a case of a 41-year-old woman with a recent secondary amenorrhea and infertility. The initial assessment ruled out premature ovarian failure, polycystic ovary syndrome and led to suspect a hypothalamo-pituitary cause. However, the unusual hormone pattern with a very low level of FSH, normal levels of LH and estradiol, associated with a positive progesterone test suggested the presence of a FSH inhibiting factor: the unexpectedly high levels of inhibin B and AMH were suggestive of a granulosa cell tumor as showed by the radiologic findings. This prompted a surgical exploration, which confirmed the putative diagnosis. This case report illustrates the inhibin B and AMH values and the modern-day pelvic imaging data encountered in menstrual irregularities caused by a granulosa cell tumor.

Inhibin-producing ovarian granulosa cell tumor as a cause of secondary amenorrhea: Case report and review of the literature

We report the case of 31-year-old patient with an inhibin B-secreting granulosa cell tumor of the left ovary who presented with secondary amenorrhea. Preoperative serum hormonal levels were as follows: follicle-stimulating hormone (FSH) 0.3 mIU/mL, luteinizing hormone (LH) 9.81 mIU/mL, estradiol 142.0 pg/mL and inhibin B 2429 pg/mL. Gonadotropin-releasing hormone (GnRH) test revealed no FSH response and a normal LH response. After removal of the tumor, the levels of FSH and inhibin B returned to within the normal range, and regular menses resumed 27 days postoperatively. In premenopausal women, secondary amenorrhea may be the initial manifestation of granulosa cell tumor. A low FSH level coupled with normal levels of E2 and LH, the inhibition of the FSH response to GnRH and an elevated inhibin level suggest the presence of an inhibin-secreting ovarian tumor and also rule out the possibility of isolated FSH deficiency.