MON-239 Pituitary Apoplexy Induced by Gonadotropin-Releasing Hormone Agonist Administration: A Rare Complication of Prostate Cancer Treatment

Background: Pituitary apoplexy is a potentially life-threatening clinical condition associated with bleeding and/or infarction into the pituitary gland, usually within a tumor. Gonadotropin-releasing hormone (GnRH) agonists, currently used in the treatment of advanced prostate cancer, have been described in the literature as a rare cause of pituitary apoplexy. Case: We report the case of a 69 year-old man with a known pituitary macroadenoma incidentally detected in 2016, without further investigation. He was diagnosed with prostate cancer in 2017 and underwent retropubic prostatectomy. Two years later there was evidence of histologic prostate tumor progression, so he started treatment with leuprorelin 45mg (GnRH agonist). Immediately after the first subcutaneous injection he presented with acute-onset severe headache, followed by left eye ptosis, diplopia and vomiting. Left cranial nerve III palsy was confirmed by examination in the emergency department. Head computed tomography showed a lesion in the sellar region; laboratory endocrine workup was significant for total testosterone 72.07 ng/dL (86.49 – 788.22), with no other abnormalities. Magnetic resonance imaging of the pituitary revealed tumor enlargement and a T1-hyperintense signal, compatible with recent haemorrhagic sellar content. The patient was managed conservatively with high dose steroids, and symptoms were significantly improved on discharge. Discussion: Pituitary apoplexy induced by GnRH agonist administration is a rare complication, described in only 20 documented cases to date. The pathophysiologic mechanism involved is not clearly established and several hypotheses have been proposed: a combination of metabolic hyperactivity, cell division/tumor growth and increased intrasellar pressure, inducing ischemia in a poorly perfused adenomatous tissue given the demand. Although uncommon, healthcare professionals should be aware of this serious consequence of GnRH agonist administration and recognize the signs, preventing a delay in diagnosis and treatment.