A 22-year-old pregnant lady presented to the Emergency Department (ED) at 36 weeks of gestation with sudden onset of severe headache and blurring of vision. On examination, she was alert, conscious (GCS: 15/15) and had bitemporal hemianopia, confirmed on formal visual field assessment. MRI brain scan (limited views due to pregnancy) showed a pituitary mass extending into the suprasellar region and reaching the optic chiasm. Serum prolactin (PRL) was elevated at 3876 μ/l (102496) and she was commenced on Bromocriptine 2.5 mg OD by the attending team and discharged home.
She was later admitted for delivery when the endocrine team was involved in further management. She was given i.v. hydrocortisone until delivery and was started on PO hydrocortisone following delivery. A short synacthen test (SST) 10 days post delivery was suggestive of cortisol deficiency (baseline cortisol of 183 nmol/l and 30 min cortisol of 399 nmol/l) and her PRL level had improved to 290 μ/l.
Three weeks post delivery, she presented to the ED with worsening of her visual symptoms. Repeat MRI brain scan showed increase in the size of the pituitary tumour with lateral extension towards the cavernous sinus and optic chiasm compression. She underwent trans-sphenoidal resection of the pituitary tumour.
Microscopic features and histology was suggestive of lymphocytic hypophysitis. Her thyroid functions, IGF1 and gonadotropins were normal. Insulin tolerance test confirmed ACTH deficiency (peak cortisol of 336 nmol/l).
Lymphocytic hypophysitis is a rare inflammatory lesion of the pituitary gland and has a female preponderance. It usually presents in late pregnancy or postpartum period. Presentation of lymphocytic hypophysitis often mimics pituitary adenoma. It has preference for destruction of ACTH and TSH secreting cells with normal gonadotropins and GH.