PurposeTo report a case of prolonged conjunctivitis as the manifestation of Granulomatosis with polyangiitis (GPA).MethodsA 37-year-old man presented with prolonged conjunctivitis which had persisted for one month. He was taking medication for his conjunctivitis without any response. A slit-lamp examination revealed conjunctivitis and scleritis in the right eye. Conjunctivitis, 360-degree peripheral corneal thinning, corneal perforation, and scleritis were seen in the left eye.ResultsEmergency penetrating keratoplasty was performed to treat the patient's corneal perforation. After a consultation with the Internal Medicine Department, the patient was suspected of having GPA with positive cytoplasmic anti-neutrophil cytoplasmic antibodies (C-ANCA). Functional endoscopic sinus surgery was performed to treat right maxillary sinusitis, and a biopsy of the maxillary sinus mucosa was obtained. The pathology report showed granuloma and vasculitis with severe acute and chronic inflammation and few eosinophils; thus, the diagnosis was confirmed.ConclusionBecause prolonged conjunctivitis occurs only rarely in association with systemic disease, ophthalmologists should be aware of this potential, particularly in patients with GPA.