Endocrine Abstracts

A 38 year old lady presented at 30 weeks gestation with a 3 week history of headaches and 5 day history of blurring of vision, worse in the left eye. Visual field testing revealed a bitemporal hemianopia. MRI scan of the pituitary showed appearances typical of a macroadenoma which was lobulated in appearance with suprasellar extension (max height 13mm) and compression of the optic chiasm. Endocrine tests indicated that thyroxine was low for the 3rd trimester (79nmol/l), with free T4 low (8pmol/l (9-22)) as was 9am Cortisol at 339nmol/l. Prolactin was appropriate at 3735 mu/l.

Management

On the premise that dopamine agonist therapy would result in decreased lactotroph hyperplasia and potentially some tumour shrinkage, we initiated dopamine agonist therapy, titrated up to the maximum tolerated dose of Bromocriptine 2.5mg tds. Soon afterwards, the headaches resolved completely. The multidisciplinary team managing the case all agreed that in view of the risks of pituitary surgery at this stage of pregnancy, pituitary decompresssion would only be carried out if the visual field defect worsened on weekly testing. In fact there was no significant visual field change up to delivery.

Course

At 38 weeks, a healthy baby boy was delivered by Caesarian section. Pituitary MRI scan 2-weeks post-partum showed complete resolution of the previously seen pituitary lesion. The suprasellar cistern was normal as was the optic chiasm. Baseline and provocative endocrine testing was normal. Visual fields were back to normal

Discussion

The rapid resolution of the pituitary swelling and lack of endocrine deficit post-partum suggest that physiological enlargement of the pituitary gland rather than lymphocytic hypophysitis was the aetiology. This case highlights the phenomenon that physiological changes in the pituitary in the later stages of pregnancy can mimic pituitary macroadenoma, and the importance of close monitoring rather than necessarily surgery in such situations.