Endocrine Abstracts

Introduction: During pregnancy, macroprolactinomas may grow to become symptomatic in 30% of cases (1). This has been reported in women diagnosed with prolactinoma before the onset of pregnancy. We report a rare case of a woman presenting with vision loss due to a previously undiagnosed compressive macroprolactinoma at the end of pregnancy.

Case report: A 31-year-old woman, at 35 weeks and 5 days of gestation, was referred for progressive visual loss in the left eye evolving over 4 months, with rapid worsening during the two weeks prior to presentation. Ophthalmologic assessment revealed a compressive optic neuropathy with visual acuity decreasing from 6/10 to 1/10 in two weeks on the left side. Optical coherence tomography showed no papillary atrophy, indicating a recent and potentially reversible visual loss. Pituitary MRI demonstrated a pituitary macroadenoma measuring 15×20×21 mm with an internal cystic component of 11×15×18 mm, compressing the optic chiasm. Serum prolactin was 368 μg/l, with normal thyroid and cortisol axes. The patient had no prior history of hyperprolactinemia. This was her third pregnancy, following two previous deliveries by cesarian section. After multidisciplinary discussions, a cesarean section (CS) was performed at 36 weeks and one day of gestation to safely deliver the baby and to prepare the mother for transsphenoidal decompression. At the same time, we started cabergoline 0.25 mg/day in an attempt to decrease the size of the adenoma and normal pituitary gland. Because no visual improvement was noted four days after CS and cabergoline initiation, a trans-sphenoidal resection of the tumor was performed. Histopathological examination showed a prolactin-secreting pituitary adenoma, PIT-1 positive, with a Ki-67 proliferation index of 6% and p53 positivity. Visual acuity improved markedly immediately after surgery. Two months post-surgery, serum prolactin had normalized to 14.3 μg/l without cabergoline and no pituitary hormone deficit was noted. Ophthalmological follow-up confirmed normalization of visual fields. Given the elevated proliferative index observed histologically, long-term follow-up is warranted to monitor for potential recurrence.

Conclusion: This case highlights the symptomatic enlargement of a previously undiagnosed prolactinoma during the third trimester leading to severe optic chiasm compression. Neurosurgical decompression was performed after cesarian section because of the advanced gestational age and in order to minimize maternal complications.

References: 1. A Luger et al, ESE Clinical practice guideline on functioning and nonfunctioning pituitary adenomas in pregnancy, European Journal of Endocrinology, 185, G1-33, 2021.

Keywords: Macroprolactinoma, pregnancy, optic chiasm, neurosurgery