Granulomatosis with Polyangiitis Presenting with Bilateral Orbital Apex Syndrome

We report a rare case of granulomatosis with polyangiitis (GPA) presenting with bilateral orbital apex syndrome (OAS). A 73-year-old woman with a history of endoscopic sinus surgery for ethmoidal sinusitis experienced a sudden decrease in visual acuity (VA) of both eyes. At the initial examination, her VA had decreased to 0.01 in the right eye and 0.03 in the left eye, and eye movement in both eyes was mildly limited in all directions. Visual field tests of both eyes showed a large central scotoma. Laboratory tests revealed an elevation of myeloperoxidase-anti-neutrophil cytoplasmic antibody. Facial computed tomography demonstrated a thickened mucosal membrane in the entire ethmoidal sinus, and the posterosuperior walls of Onodi cells filled with infiltrative lesions had thinned. Orbital magnetic resonance imaging showed severe inflammation in the orbital apex. From these clinical findings, the patient was diagnosed with GPA presenting with OAS associated with ethmoid sinusitis. Emergent endoscopic sinus surgery was performed for biopsy and debridement of the ethmoidal and sphenoid sinusitis to decompress the optic nerve. One day after endoscopic sinus surgery, the patient's VA and visual field were improved, and steroid pulse therapy was commenced postoperatively. Four days later, VA had recovered to 1.0 in both eyes, and eye movement and visual field had were improved. Although OAS is a rare manifestation, early surgical treatment should be considered when the orbital lesion presents as risk of rapid deterioration of visual function in patients with GPA.