Pituitary Hyperplasia Causing Complete Bitemporal Hemianopsia with Resolution Following Surgical Decompression: Case Report

Introduction: Pituitary hyperplasia (PH) may occur in the setting of pregnancy or end-organ insufficiency, as well as with medications such as oral contraceptives and antipsychotics, or may be idiopathic.[1] Pituitary size may vary according to gender and age, and gland enlargement in a young and healthy woman may be defined with a height of >9 mm.[2] PH is often found incidentally and surgical intervention is usually unnecessary, as it rarely progresses and may be managed by treating the underlying etiology.[1] The objective of this clinical case report is to demonstrate a case of a patient with idiopathic PH who developed complete bitemporal hemianopsia and amenorrhea despite benign imaging and laboratory findings.

Case Description: We present the case of a twenty-four year old woman with no significant past medical history, who presented with a 3-week history of visual disturbances. The patient was evaluated by a neuroophthalmologist who identified a left temporal visual field defect on visual field testing. Brain MRI revealed a 4–5 mm hypoenhancing focus within the inferior pituitary gland that was concerning for a pituitary microadenoma. The gland appeared to be enlarged, touching and abutting the chiasm, but no significant anatomical compression was noted. The patient also reported amenorrhea over the previous seven months with a negative pregnancy test. Pituitary function tests were within normal limits. Follow-up visual field testing 2 weeks after the initial evaluation showed progression of the visual field defect to complete bitemporal hemianopsia. Repeat MRI imaging did not show significant changes, with exception of the complete disappearance of the 4–5 mm hypoenhancing lesion. The patient was offered sellar decompression, biopsy and gland exploration, and elected to proceed with surgery. She underwent surgical decompression of the anterior and inferior walls of the sella turcica, dural opening, biopsy, and exploration of the gland through an endoscopic endonasal transsphenoidal approach. No tumor was identified. The patient's vision immediately improved after surgery and a follow-up visual field exam revealed complete resolution of the bitemporal hemianopsia. Menstruation resumed three days later, and postoperative cortisol levels were within normal limits. The patient remains asymptomatic. Pathology results demonstrated pituitary hyperplasia.

Conclusion: In this report, we illustrate how PH can cause complete bitemporal hemianopsia, even in the setting of mild anatomical compression of the optic chiasm. In these cases, complete resolution of the symptoms can be achieved with surgical decompression.

• References

• De Sousa SM, Earls P, McCormack AI. Pituitary hyperplasia: case series and literature review of an under-recognised and heterogeneous condition. Endocrinol Diabetes Metab Case Rep 2015; 2015: 150017
• Chanson P, Daujat F, Young J, et al. Normal pituitary hypertrophy as a frequent cause of pituitary incidentaloma: a follow-up study. J Clin Endocrinol Metab 2001; 86 (07) 3009-3015