SAT-LB54 Acute Sterile Meningitis as a Primary Manifestation of Pituitary Apoplexy

Background: Pituitary apoplexy (PA) is a rare endocrinopathy that requires prompt diagnosis and treatment. Presentation with acute neutrophilic meningitis is uncommon. Clinical Case: A 67-year-old man presented to our hospital with a 2-week history of worsening bilateral frontal headache, nausea, and dry heaving. On admission, the patient was somnolent with a score of 13 on the GCS assessment (E2, V5, M6). The neurological exam was overall normal with normal ocular motion and intact cranial nerves, except for a left eye peripheral vision defect. Plain head CT revealed a well-circumscribed ovoid pituitary mass with suprasellar enlargement, consistent with a pituitary macroadenoma. Sellar MRI showed a pituitary mass, roughly 20 x 19 x 24 mm, bulging into the suprasellar cistern with optic chiasm elevation. Analysis of pituitary function revealed low ACTH concentration of 2.8 pg/mL (n = 7.2 - 63.3 pg/mL), a low random cortisol level of 1.7 ug/dL (n = 2.9 - 19.4 ug/dL), a low TSH of < 0.1 uIU/mL (n = 0.35 - 4.9 uIU/mL), a low free T4 level of 0.72 ng/dL (n = 0.77 - 1.48 ng/dL), a low LH of 0.8 IU/L (n = 1.7 - 8.6 IU/L) with a very low total testosterone level of < 3 ng/dL (n = 300 - 720 ng/dL) and normal prolactin, IGF-1 and GH levels. On hospital day 2, the patient had worsening encephalopathy with left eye ptosis and decreased vision. Repeat CT and MRI showed no interval change in the pituitary adenoma or evidence of bleeding. An immediate lumbar puncture was performed and CSF analysis revealed an increased leukocyte count of (1106/mm3) with 89% neutrophilic granulocytes, and increased total protein level of 138 mg/dL (n = 15 - 40 mg/dL), red blood cell count of 2040 without xanthochromia and glucose of 130 mg/dL (n = 40 - 70 mg/dL). Based on the laboratory results and new symptoms, empirical antibiotic (vancomycin, ceftriaxone, and ampicillin) therapy was started for suspected bacterial meningitis before the confirmation of the CSF culture study. CSF culture did not grow any organisms. Given the sudden visual impairment and neurological deterioration, the patient underwent transsphenoidal resection of the tumor with free nasal mucosal graft reconstruction. Histological examination revealed a necrotic pituitary adenoma with apoplexy and no evidence of hemorrhage. Postoperatively, his neurological exam greatly improved. His left pupil was reactive to light and the third palsy was improving. Conclusion: This case reinforces the importance of including PA in the differential diagnosis of acute headache, particularly in patients presenting with visual disturbances. Patients with PA often present with sterile meningitis due to increased debris and blood in the subarachnoid space which closely mimics acute bacterial meningitis. While MRI remains a sensitive imaging modality for the detection of PA, the latter remains a clinical diagnosis. Timely diagnosis with high clinical suspicion and treatment is essential.