A 33-year-old Caucasian female presented with ten-months history of amenorrhea and two months history of spontaneous galactorrhoea. She had a successful IVF pregnancy with embryo transfer 3 years previously for unexplained infertility. Her Body Mass Index was 37. No symptoms or signs suggestive of hypercortisolism or acromegaly. Her pituitary profile showed prolactin: 1698 IU/ml (40-500) and raised IGF1: 416 mcg/l (109324), with normal Follicular Stimulating Hormone, Luteinizing hormone, Steroid Hormone Binding Globulin, estradiol, cortisol and Thyroid Function Test. OGTT with GH measurements were normal including IGF1 binding protein 3: 3.6 ug/l (1.7-5.2). MRI head revealed Pituitary macroadenoma15×21×19 mm. She was commenced on cabergoline 250 mcg/week.
After 6 months on treatment, she had regular periods with no galactorrhoea, but had new symptoms of fatigue and excessive sweating. Her weight remained stable. No symptoms or signs suggestive of hypercortisolism. No signs of acromegaly. Her prolactin was suppressed (36 IU/l) but IGF1 415 mcg/L level remained high. Repeat OGTT with GH measurement showed unsuppressed GH suggestive of acromegaly. She recovered from an episode of mild pituitary hemorrhage. She was commenced on levothryoxine therapy. Repeat MRI showed enlarging pituitary adenoma 18×22×23 mm. Referred for neurosurgical intervention.
Cabergoline was stopped and patient had transphenoidal resection that revealed aggressive Acidophilic stem cell pituitary adenoma with negative GH immunostain. Postoperative MRI pituitary showed no residual tumor. Hormonal profile showed raised prolactin 708 IU/l pending IGF1 level. Clinically she remains asymptomatic and awaiting treatment for uterine polyp and also planning embryo transfer IVF in near future.
Acidophilic stem cell pituitary adenoma is a rare aggressive tumor. It is an immature neoplasm developing from common progenitor cells of the growth hormone and prolactin cells. In our patient, clinical and biochemical evidence of acromegaly was revealed once on Cabergoline therapy, interestingly immunostaining was negative for GH.
Keywords: IVF- invitriofertilization, IGF1- insulin growth factor 1, OGTT- oral glucose tolerance test, GH- growth hormone, MRI- magnetic resonance imaging.