7102 Pituitary Apoplexy with Eventual Complete Tumour Involution

Abstract Disclosure: A. Ng: None. R. Lai: None. Pituitary apoplexy is an endocrinological emergency resulting from infarction or haemorrhage of the pituitary gland. We present a case of pituitary apoplexy from a non-functioning pituitary macroadenoma, complicated by pituitary insufficiency and subsequent tumour involution. An 80-year-old gentleman presented to the Emergency Department with sudden severe headaches and persistent vomiting and admitted for further evaluation. Computed tomography (CT) imaging of the brain showed a prominent pituitary gland and magnetic resonance imaging (MRI) confirmed a large sellar hyperintense lesion containing blood and proteinaceous material. It measured 1.6 cm by 1.2 cm by 1 cm and indented the optic chiasm. CT angiography did not reveal any aneurysms or intracranial haemorrhage. There were no neurological or visual field deficits at presentation. There was no indication for surgery upon neurosurgical consultation. Initial evaluation of the pituitary axis was consistent with central hypocortisolism (cortisol 75 nmol/L, adrenocorticotropic hormone 1.4 pmol/L reference range (RR) 1.6-13.9) and hypoprolactinaemia (prolactin 56 mIU/L, RR 73-351). Luteinising hormone levels were 1 IU/L (RR 1-9); follicle stimulating hormone levels were 3 IU/L (RR 1-19) and testosterone levels were 1 nmol/L (RR 5 to 30) as the patient was on androgen deprivation therapy for prostate cancer. Hydrocortisone was started and he was monitored for development of frank diabetes insipidus. He did not require regular desmopressin. He later developed anti-diuretic hormone mediated hyponatraemia (serum sodium nadir of 125 mmol/L, serum osmolality 275 mmol/kg, urine osmolality 390 mmol/kg) that was managed with fluid restriction and solute loading. He also developed central hypothyroidism on day 19 of admission (free thyroxine 11 pmol/L, thyroid stimulating hormone 0.49 mIU/L, RR 0.45-4.5) and oral levothyroxine was started. He was discharged with oral hydrocortisone and levothyroxine replacement. A repeat MRI of the pituitary 2 months later showed complete resolution of the mass and resolution of the mass effects. He was kept on oral hydrocortisone and levothyroxine replacement with regular follow-up.Most pituitary macroadenomas are non-functional, and can present with complications of apoplexy, mass effects or hormonal disturbances. However, the natural history of non-functional macroadenomas is not well known as most are operated on. Spontaneous regression of the tumour can rarely occur, notably in the setting of apoplexy and lymphocytic hypophysitis. Recovery of the pituitary axis may also accompany tumour regression. As spontaneous remission of pituitary macroadenomas may occur, close observation of tumours without visual field defects or significant mass effects may be an alternative to surgery. Presentation: 6/1/2024 12:15:00 PM