A Follicular Stimulating Hormone Secreting Adenoma

A gonadotroph secreting pituitary adenoma, a rare endocrinopathy, is often overlooked due to ambiguous symptoms leading to other diagnoses, such as ovarian hyperstimulation syndrome (OHSS). A 53 year old African American woman presented for evaluation of a 4 month history of right hemianopsia. Her past medical history included a total hysterectomy and bilateral oophorosalpingectomy for recurrent ovarian cysts 11 years prior. Initial MRI:4.1x3.6x3.9 cm pituitary macroadenoma with prechiasmtic optic nerve compression. Initial laboratory studies: follicular stimulating hormone (FSH) level 186.83 mIU/mL (RR:23.0-116.3 mIU/mL) and luteinizing hormone (LH) 14.44 mIU/mL (RR:15.9-54.0 mIU/mL). Other pituitary labs were unremarkable. Debulking surgery was performed to relieve mass effect; pathology showed an FSH immunoreactive adenoma. Postoperatively, FSH was 2.55 mIU/mL and LH was 0.75 mIU/mL. The prevalence of pituitary adenomas is 80-100 per 100,000 persons; 15-30% are non-functional. The majority of gonadotroph adenomas are difficult to identify because they may not produce biologically active hormones. Clinically functioning gonadotroph adenomas are very rare, often macroadenomas when found, most often found in reproductive age women, and preferentially secrete FSH. In reproductive age women, a FSH secreting adenomas may present clinically with OHSS, with multiple large ovarian cysts found on ultrasound for menstrual or pelvic complaints as seen in our patient. While OHSS is a known complication of assisted reproductive procedures, spontaneous OHSS is atypical and suggests need for evaluation of a FSH-secreting adenoma. Men may present with macroorchidism. Children may present with precocious puberty. The treatment of choice is surgical removal of the adenoma, normalizing FSH to an age appropriate level. When OHSS is present, this results in a rapid decline in estradiol level and regression of ovarian cysts. Medical treatment, if surgery is contraindicated, is limited to cabergoline, which can initially decrease FSH and estradiol levels. In patients with normal pituitary function, gonadotropin-releasing hormone agonists acutely stimulate LH and FSH, thereby desensitizing GnRH receptors and decreasing gonadotropin secretion. In patients with FSH-secreting adenomas, they may have a persistent stimulatory effect, and in rare cases, result in pituitary apoplexy. Tumors that cannot be completely surgically removed may be treated by adjuvant radiotherapy or radiosurgery.