Giant Sellar Meningocele: Intact Pituitary Function and New-onset Arginine Vasopressin Deficiency After Surgery.

Sellar and sphenoidal meningoceles are rare entities that can lead to neurological, ophthalmological, and endocrine complications. We report the case of a 28-year-old man with a giant sellar meningocele who presented with chronic headache and bitemporal hemianopsia but with preserved pituitary function at diagnosis. Magnetic resonance imaging revealed a large defect of the sellar floor with herniation of meninges and displacement of the optic chiasm and pituitary gland. The patient underwent endoscopic transsphenoidal repair. Within 24 hours, he developed arginine vasopressin (AVP) deficiency requiring long-term desmopressin therapy, which persisted beyond 6 months, fulfilling the criteria for permanent AVP deficiency. No other pituitary hormone deficits were observed. Visual field impairment did not improve after surgery, although further deterioration was prevented. This case underscores that adult sellar meningoceles can present with intact anterior pituitary function but still carry a risk of isolated permanent AVP deficiency after surgical repair. To our knowledge, this is among the largest adult sellar meningoceles reported with preserved anterior pituitary function at presentation and subsequent permanent isolated AVP deficiency, emphasizing the need for careful perioperative counseling and long-term endocrine follow-up.