Eosinophilic Granulomatosis With Polyangiitis Presenting With Neuro-Ophthalmic Manifestations.

A 45-year-old man reported progressively worsening vision, photophobia, and dyschromatopsia in the left eye as well as oblique binocular diplopia. His neuro-ophthalmic examination was significant for ophthalmoplegia and optic disc edema in the left eye. MRI of the brain and orbits showed enlargement and contrast enhancement of the left lateral rectus muscle, optic nerve sheath, and cavernous sinus. He was started on corticosteroids with improvement in his symptoms, examination, and imaging. However, on cessation of corticosteroids, he developed worsening symptoms. Biopsy of the left lateral rectus muscle showed reactive lymphoid infiltrates with eosinophilia and no evidence of malignancy. While off corticosteroids, a complete blood count with differential revealed peripheral eosinophilia. He was diagnosed with eosinophilic granulomatosis with polyangiitis (EGPA) and ultimately started on steroid-sparing therapy with mepolizumab. EGPA may present with primarily ocular or orbital involvement.