Expecting the unexpected: a case of a newly diagnosed pituitary adenoma in pregnancy — ASN Events
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Expecting the unexpected: a case of a newly diagnosed pituitary adenoma in pregnancy (#431)

Chih Ying (Maggie) Ko 1 2 , Ning Zhang 1 2 , Mikey Xie 1 2 , Sarah Abdo 2 3 , Tang Wong 1 2 3
  1. School of Clinical Medicine, Faculty of Medicine and Health , UNSW, Sydney, NSW, Australia
  2. Diabetes and Endocrinology, Bankstown Lidcombe Hospital, Bankstown, NSW, Australia
  3. School of Medicine, Western Sydney University, Sydney, NSW, Australia

Prolactinomas are typically associated with reduced fertility, and current guidelines focus on management from preconception through pregnancy and the postpartum period1. We present a challenging case of a newly diagnosed pituitary macroprolactinoma causing visual field deficits during the third trimester of pregnancy.

A 35-year-old G2P0 woman presented at 35 weeks' gestation with headache and bitemporal superior quadrantanopia. Her pregnancy was complicated by gestational diabetes and subclinical hypothyroidism. She reported previously regular menstrual cycles and conceived within 6 months of attempting pregnancy. MRI of the brain demonstrated a 17 mm pituitary macroadenoma with superior displacement of the optic chiasm. Serum prolactin was markedly elevated at 19,742 mIU/L, while the remainder of her pituitary hormones were appropriate for pregnancy. Review of prior imaging revealed that an MRI performed 5 years earlier for headaches had demonstrated a 9 mm pituitary adenoma, although this had not been recognised at the time.

Following multidisciplinary discussion involving endocrinology, neurosurgery, and obstetrics, cabergoline 0.5 mg weekly was commenced given her visual field impairment. She was monitored weekly for the remainder of her pregnancy for evidence of tumour progression or pituitary apoplexy. After initiation of cabergoline, prolactin levels progressively declined and visual fields improved, with complete resolution of the right-sided defect and only mild residual left superotemporal visual field loss. At 39 weeks' gestation, she delivered a healthy infant without maternal or neonatal complications. Given the size of the tumour and persistent superior displacement of the optic chiasm, breastfeeding was discouraged. MRI performed 4 weeks postpartum demonstrated tumour shrinkage to 12 mm, and prolactin normalised to 106 mIU/L.

This case highlights the challenges of managing a newly diagnosed macroprolactinoma late in pregnancy. Prompt multidisciplinary management, careful monitoring for tumour progression and pituitary apoplexy, and timely initiation of dopamine agonist therapy can result in favourable maternal and fetal outcomes.

  1. Luger A, Broersen LHA, Biermasz NR, Biller BMK, Buchfelder M, Chanson P, Jorgensen JOL, Kelestimur F, Llahana S, Maiter D, Mintziori G, Petraglia F, Verkauskiene R, Webb SM, Dekkers OM. ESE Clinical Practice Guideline on functioning and nonfunctioning pituitary adenomas in pregnancy. Eur J Endocrinol. 2021 Aug 23;185(3):G1-G33. doi: 10.1530/EJE-21-0462. PMID: 34425558.