A Challenging Case of Pituitary Macroprolactinoma During Pregnancy

Introduction: Prolactinoma is the most common secreting pituitary adenoma diagnosed in women of reproductive age. The mainstay of treatment is pharmacotherapy with dopamine agonists. Management during pregnancy poses a considerable challenge to physicians. We describe a case of a patient who developed significant symptoms of pituitary enlargement following cessation of Cabergoline in pregnancy. Case Description: A 28-year-old female presented at age 16 with galactorrhea and oligomenorrhea. She was treated with Cabergoline for 12 years. Her peak prolactin was 191ng/ml (normal range, non-pregnant: 2.8-29.2ng/ml, pregnant: 9.7- 208.5ng/ml). On MRI, she had a 1cm tumor that was stable from 2016 to 2019. Prior to recent pregnancy, she remained compliant with Cabergoline 1.5mg twice weekly with prolactin levels that ranged between 30-44 ng/ml. After becoming pregnant in August 2019, Cabergoline was discontinued. During pregnancy, she did not initially schedule follow up with endocrinology. She developed blurred vision at 12 weeks gestation but did not seek medical care until 24 weeks gestation, at which time she was found by Ophthalmology to have bitemporal field cuts. MRI pituitary at 26 weeks showed marked enlargement and evidence of a left sided pituitary macroadenoma measuring 2cm with hemorrhagic component, suprasellar extension compressing the optic chiasm and subtle extension into the left cavernous sinus. She was recommenced on Cabergoline 1.5mg twice weekly but had no improvement in visual changes or MRI findings after two weeks. Her prolactin level at 30 weeks gestation was 170ng/ml. Neurosurgical evaluation resulted in urgent endoscopic transsphenoidal surgery at 30 weeks and pathology was consistent with prolactinoma. Post-operative outcomes were favorable with no evidence of pituitary hormonal deficiencies. Her visual abnormalities resolved, and she underwent delivery via C-section at 38 weeks gestation. She had intermittent breast milk production and her baby is in good health. She remains off Cabergoline with a prolactin level of 2.38ng/ml and no residual disease on MRI done 6 months postop. Conclusion: Tumor growth causing significant symptoms requiring intervention has been reported in 2.4% of microadenomas and 21% of macroadenomas. It is essential to periodically assess visual fields during pregnancy particularly in patients with macroadenomas. Dopamine agonists are discontinued during pregnancy unless symptomatic enlargement of prolactinoma occurs. In such cases, reinstitution of dopamine agonists usually results in positive outcomes and delivery can be considered if appropriate for gestational age. Further deterioration or lack of improvement necessitates urgent neurosurgical intervention in cases such as our patient.