Rapid Improvement of Visual Field Defect with Medical Treatment in Giant Prolactinoma with Optic Nerve Compression

Document Type

Abstract

Publication Date

10-1-2024

Abstract

Introduction: Prolactinomas are the most common form of pituitary adenomas of which micro-prolactinomas comprise of 90% and measure less than 1 cm and occur mostly in women. Giant prolactinoma, defined as a prolactinoma >4 cm, serum prolactin concentration higher than 1000 ng/mL, and invasive tumor growth pattern with mass effects occur mostly in men. Giant prolactinomas have an estimated prevalence of 0.5-4.4% of all pituitary tumors. We report a case of giant prolactinoma causing optic nerve compression that responded well to Cabergoline. Case description: 47-year-old male with no significant past medical history was having vision disturbances for 6 months which included blurry vision and was seen by ophthalmologist. Visual field testing was done and was found to have bitemporal visual field defect/heteronymous hemianopia which prompted an emergent MRI of brain which showed 4.1x3.1x3.1 cm pituitary macroadenoma with suprasellar extension compressing the optic chiasm and optic nerves as well as the inferior anterior portion of the third ventricle and adjacent cerebrum. He was referred to neurosurgery and endocrinology. He reported intermittent headaches occurring 3-4 times a week. Denied any weakness, bowel/ bladder incontinence. He denied any significant weight gain or weight loss, no palpitations, or severe fatigue. Hormonal work up showed: Elevated Prolactin level 9226 ng/ml (Reference range 2-18 ng/ml), Low Total testosterone was 213 ng/dL (Reference range 250-1100 ng/dL), low free testosterone 31.3 pg/ml (Reference range 35-155 pg/ml), with inappropriately normal luteinizing hormone and follicle stimulating hormone consistent with central hypogonadism. Thyroid stimulating hormone, free thyroxine, adrenocorticotropic hormone, am cortisol, Insulin like growth factor-1, and serum sodium were normal. He was seen in endocrinology clinic and started on cabergoline 0.5 mg twice a week. Repeat prolactin level in 3 weeks decreased to 285 ng/ml. Repeat visual field testing in 2 weeks after starting cabergoline showed that the bitemporal visual field defect had improved. His headache has improved and has intermittent episodes of dizziness. Discussion: There are few case reports describing giant prolactinoma, however there are no clear guidelines for management of giant prolactinomas causing optic nerve compression leading to visual field defects. Medical management of prolactinomas include dopamine agonists like Cabergoline, bromocriptine which are first line. The dilemma between choosing medical versus surgical management occurs in cases where there is worsening of visual field defects. Our case report highlights the drastic improvement in visual field defect and prolactin level after starting cabergoline within 3 weeks.

Publication Title

Journal of the Endocrine Society

Volume

8

Issue

Supplement 1

First Page

A686

Last Page

A687

Link to Full Text

Open Access

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