MON-261 Pituitary Abscess Presenting as Pituitary Macroadenoma Causing Hypopituitarism and Acute Meningitis; A Wolf in Sheep’s Clothing

Abstract Background: Pituitary abscess (PA) is a rare but life-threatening cause of suprasellar (SS) lesion and pituitary hormonal deficiencies with an incidence of 0.2% - 1.1%. Clinical Case: A 65-year woman with history of transient ischemic attacks, presented with double vision for 3 months (mon) and sudden onset, severe headache. She was diagnosed with cranial nerve (CN) VI palsy. MRI brain showed 1.7 cm SS mass suggestive of pituitary macroadenoma abutting optic chiasm. Visual field testing was unreliable due to underlying visual defects. She had progressive improvement in her diplopia. She was referred to Endocrinology for worsening fatigue. Physical exam was unremarkable. Pituitary hormonal work up showed secondary hypothyroidism with TSH 1.17 mIU/L (0.4-4.5), free T4 0.6 ng/dL (0.8-1.8); hypogonadotropic hypogonadism with FSH 12 mIU/ml (23-116.3), LH 1.7 mIU/ml (10-54.7), estradiol <15 (<31); elevated prolactin due to stalk affect with prolactin level of 83.3 ng/mL (3-30). She had normal IGF-1 of 154 ng/mL (41-279), ACTH 12 pg/mL (6-50), cortisol 14.1 mcg/dL (4-22) and mildly low sodium 134 mmol/L (135-146). Levothyroxine 50 mcg daily was started. The MRI brain at 2 mon and 6 mon follow up showed stable 1.8 cm peripherally enhancing SS mass. She was planned for elective pituitary adenoma resection but prior to that that was emergently admitted to ICU with high grade fever, confusion, seizures, severe hyponatremia with sodium of 122 mmol/L (135-146) and a concern for meningitis. She had a dental crown placed 3 weeks ago. MRI brain showed increase in size of the cystic component of SS mass. She was started on empiric IV antibiotics and high dose steroids. She underwent trans-sphenoidal surgery (TSS), and actually found to have a pituitary abscess. Gram stain of purulent material was positive for neutrophils. Pathology showed pituitary gland with focal infarct and surrounding acute on chronic inflammation and fibrosis. The intra-operative abscess cultures grew Cutibacterium (Proprionibacterium) acnes. She is planned to receive 6 weeks of IV antibiotics. Conclusion: We present a case of pituitary abscess presenting as a SS mass causing hypopituitarism. It was presumed pituitary macroadenoma due to the sub-acute onset and lack of progression. She developed acute deterioration in sensorium leading to concern for meningitis and PA requiring timely diagnosis and management with trans-sphenoidal resection and IV antibiotics. Definitive diagnosis of PA is usually made post-operatively. 60% of patients with PA and new onset hypopituitarism may require long term hormone replacement. References: 1. Agyei JO, Lipinski LJ, Leonardo J. Case Report of a Primary Pituitary Abscess and Systematic Literature Review of Pituitary Abscess with a Focus on Patient Outcomes. World Neurosurg. 2017 May;101:76-92