Giant intrasellar arachnoid cyst manifesting as adrenal insufficiency due to hypothalamic dysfunction--case report--.

A 67-year-old man first noticed loss of pubic and axillary hair in 1992 and then a visual field defect in 2001. He experienced loss of consciousness attributed to hyponatremia in April 2002. Magnetic resonance imaging showed a giant intrasellar cystic mass, 40 mm in diameter, that had compressed the optic chiasm. The patient complained of chronic headache, and neurological examination revealed bitemporal hemianopsia. Preoperative endocrinological examination indicated adrenal insufficiency, and hypothyroidism due to hypothalamic dysfunction. The patient underwent endonasal transsphenoidal surgery. The cyst membrane was opened and serous fluid was drained. Histological examination identified the excised cyst membrane as arachnoid membrane. The patient's headaches resolved postoperatively, but the bitemporal hemianopsia and endocrinological function were unchanged. This arachnoid cyst associated with hypothalamic dysfunction might have been caused by an inflammatory episode in the suprasellar region.