Case
A 36 year old female, with no past medical history, presented to her general practitioner at 25 weeks’ gestation with retro-orbital pressure and left eye ptosis. Ophthalmology assessment at 30 weeks’ gestation confirmed a 3mm left upper eyelid ptosis but was otherwise unremarkable. Magnetic resonance imaging (MRI) performed at 33 weeks’ gestation because of worsening symptoms demonstrated a 22x11x11mm pituitary lesion, extending into the left cavernous sinus and encasing the left internal carotid artery. Examination findings were in keeping with a partial third cranial nerve palsy with no visual threat. Prolactin concentration was elevated at 4440mIU/L, consistent with the third trimester of pregnancy and cortisol 612nmol/L (100-540), an expected physiological response in pregnancy. IGF-1, TSH, FT4 and 24 hour urinary free cortisol were in the normal range.
In the following weeks, her third nerve palsy progressed. Poor eye adduction and new anisocoria were observed despite a trial of dexamethasone initiated by the neurosurgical team. There had been no evidence of foetal compromise. A caesarean section was performed at 35 weeks’ gestation due to deterioration of maternal neurological symptoms and the lack of effective medical therapy.
There were no perioperative complications. Symptoms improved after delivery. Prolactin concentration initially dropped to 941 mIU/L but later peaked at 2422mIU/L, due to breastfeeding which is now being weaned after 12 months. Repeat MRI has shown no change in tumour size.
Discussion
New diagnosis of nonfunctioning pituitary macroadenomas in pregnancy is rare.1 Lactotroph hyperplasia caused by the stimulatory effect of oestrogen can infrequently result in clinically significant tumour expansion.2 Mean prolactin concentration of up to 4092 mIU/L may be observed in the third trimester.3 There are no guidelines to assist with management of these tumours in pregnancy. This case highlights the challenges faced when managing clinically worsening non-functioning pituitary adenomas in pregnant women.