Endocrine Abstracts

Case history: A 33 year old lady with irregular menstrual cycles and infertility presented to gynaecologist with recurrent abdominal pain and bloating. Her pain was found secondary to bilateral ovarian cysts. She had repeated laparoscopic ovarian cystectomies since 2018. In December 2021, modest hyperprolactinemia (1065MIU/L, RR 102-496) with negative macroprolactin test was noted, and MRI pituitary revealed 18x17x13mm pituitary macroadenoma. Cabergoline was started and she was referred to endocrine team. A diagnosis of non-functioning pituitary macroadenoma unrelated to ovarian cysts was initially considered. However, on further review of pituitary profile, inappropriately normal FSH levels (even with raised 17-β oestradiol) and suppressed LH levels were noted. Therefore, FSH secreting pituitary tumor (FSHoma) was considered, and it was concluded that recurrent ovarian cysts were attributed to spontaneous ovarian hyperstimulation syndrome in absence of using ovulation inducing agent.

Investigations: MRI pituitary (December 2021) - 18x17x13mm pituitary macroadenoma with mild suprasellar extension indenting the optic chiasm along with deviation of the pituitary stalk towards left. Visual fields- normal.

Results and treatment: With cabergoline, her abdominal symptoms along with estrogen and prolactin levels settled. However, interval MRI pituitary 6 months later revealed no change in size of pituitary macroadenoma. After discussion in pituitary MDT, transsphenoidal surgery with hope of preventing ovarian cyst recurrence was recommended.

Conclusion and point of discussion: FSHomas are usually non-functioning rare pituitary tumors, with no clinical evidence of hormonal hypersecretion. When functioning, the continuous FSH exposure from FSHoma can cause ovarian hyperstimulation syndrome due to associated raised estrogen levels. The characteristics of FSHoma in reproductive-aged women are enlarged multicystic ovaries, elevated serum 17-β oestradiol, normal to mildly raised FSH, suppressed LH, menstrual disorder, infertility, and ovarian hyperstimulation. In this case normal FSH level in setting of raised estrogen and suppressed LH was overlooked at first instance. Diagnosis of FSHoma is further supported by elevated serum alpha subunit levels. In many patients with FSHoma, accurate diagnosis is often delayed by several years and many women might have undergone repeated ovarian procedures that are detrimental to the ovarian function of infertile patients.