Ipilimumab-induced Adenohypophysitis and Orbital Apex Syndrome: Importance of Early Diagnosis and Management

Ipilimumab is a novel anti-melanoma agent known to infrequently cause multi-organ autoimmunity. We report a case of pituitary hypophysitis and orbital inflammation followed by an orbital apex syndrome. A 64-year-old woman with a history of skin melanoma, receiving ipilimumab treatment, was seen for near total loss of vision in the right eye and proptosis. Headache of 3-month duration preceded the onset of diplopia followed by severe loss of vision in the right eye. Neuro-ophthalmologic examination was consistent with an orbital apex syndrome. Extensive blood work and magnetic resonance imaging of the brain and orbit suggested an inflammatory process, rather than a metastatic lesion. Accordingly, the patient received high-dose methylprednisolone followed by tapering oral prednisone. At the 6-month follow-up visit, visual acuity on the right eye had significantly improved but diplopia remained, associated with large amplitude esotropia that improved incompletely though while on prednisone. The favourable outcome supported a final diagnosis of ipilimumab-induced inflammatory orbital apex syndrome and clinically silent pituitary adenohypophysitis. The case presented herein highlights unexpected ipilimumab-associated adverse effects and proposes the possibility of and interaction between inflammatory and immune mechanisms.