ODP318 Idiopathic Granulomatous Hypophysitis : A Rare Cause of Hypopituitarism

INTRODUCTION: Pituitary hypophysitis is an inflammatory disorder classified as primary or secondary. The five histologic subtypes of primary hypophysitis are lymphocytic, granulomatous, xanthomatous, IgG4-related, and necrotizing. Idiopathic granulomatous hypophysitis (IGH) has an incidence of 1 in 10 million and accounts for < 1% of cases involving panhypopituitarism, headache, and visual disturbances. We present the case of IGH in a patient initially suspected to have pituitary adenoma. CASE PRESENTATION: A 54-year-old female with a history of hypertension presented to the emergency department with nausea, vomiting, and acute worsening of a chronic headache of 1-week duration. Her past medical history was significant for a suspected pituitary macroadenoma of 1.7 cm, which was incidentally detected 7 months before the current presentation. She reported a history of 9 lb weight gain in one month, hot flashes, and diplopia, but denied hirsutism, polyuria, polydipsia, and galactorrhea. Prior evaluation revealed normal prolactin, TSH, and visual field testing. Her medication and familial history were unremarkable. Physical exam during the current presentation revealed stable vital signs, left eye exophthalmos, left anisocoria, decreased sensation in the left V1 and V2 trigeminal nerve distribution, and right abducens nerve palsy. Her initial laboratory workup was consistent with panhypopituitarism. Brain Magnetic Resonance Imaging (MRI) revealed an extensive, locally invasive, exuberantly enhancing infiltrative process measuring at least 5.6 cm in maximal transverse diameter involving the pituitary gland with bilateral cavernous sinus and Meckel's caves invasion and extension into bilateral superior orbital fissures. The patient underwent supraorbital craniotomy with subtotal resection of the tumor. Tuberculosis, sarcoidosis, and neoplasm were ruled out by appropriate tests, and the patient was diagnosed to have IGH on histology. Her symptoms improved postoperatively and the patient was discharged on levothyroxine and hydrocortisone. CONCLUSION: Clinically and radiologically, IGH is a rare pathology that can closely mimic a pituitary adenoma. Through this case, we highlight the importance of performing a comprehensive evaluation with a full hormonal workup and imaging, with the exclusion of secondary causes while assessing patients with a sellar mass. Presentation: No date and time listed