Complete and Uneventful Recovery in a Case of Lymphocytic Hypophysitis Causing a Third Nerve Palsy

Lymphocytic hypophysitis (LH) is a neuroendocrine disorder characterised by autoimmune inflammation of the pituitary gland with resultant pituitary dysfunction. Rarely, the presenting symptom can be diplopia due to irritation of the third, fourth, or sixth cranial nerves secondary to cavernous sinus involvement of the mass or increased intracranial pressure. We describe the case of a healthy, 20-year-old female with a pupillary sparing third nerve palsy, who was subsequently diagnosed with LH after an endoscopic transsphenoidal biopsy of the mass. She was treated with hormone replacement therapy and corticosteroids, resulting in full resolution of symptoms with no recurrence to date. To our knowledge, this is the first report of a third nerve palsy due to definitive biopsy proven LH. Despite its rarity, the unique presentation and favourable evolution of this case should aid clinicians in its timely recognition, appropriate workup, and treatment.