Peripheral Ulcerative Keratitis as an Initial Manifestation of Granulomatosis with Polyangiitis in a Pediatric Patient: A Case Report.

Purpose: To describe a rare case of pediatric granulomatosis with polyangiitis (GPA) initially presenting as peripheral ulcerative keratitis (PUK), followed by orbital inflammation, highlighting the diagnostic challenges and importance of early recognition.

Methods: A 12-year-old boy with a prior history of allergic conjunctivitis presented with unilateral peripheral corneal opacities. The condition was initially misdiagnosed and treated as infectious keratitis and allergic conjunctivitis without improvement. Comprehensive clinical, serologic, and imaging evaluations were performed, including ANCA testing, chest and orbital CT scans, and infectious serologies.

Results: Laboratory workup revealed elevated inflammatory markers, positive p-ANCA, and high anti-myeloperoxidase (MPO) antibody titers. Chest CT showed pulmonary nodules consistent with vasculitic involvement. The patient subsequently developed orbital pseudotumor and recurrent epistaxis, consolidating the diagnosis of GPA despite MPO-ANCA positivity, which is more commonly linked to microscopic polyangiitis. Immunosuppressive therapy with systemic corticosteroids and methotrexate led to complete remission of ocular inflammation, resolution of orbital involvement, and preservation of 20/20 visual acuity bilaterally after one year of follow-up.

Conclusion: This case represents an exceptional pediatric presentation of GPA, with PUK as the sole initial manifestation preceding systemic disease. It underscores the need for heightened clinical suspicion in children with atypical peripheral keratitis unresponsive to standard therapy. Early recognition and multidisciplinary management are crucial to prevent irreversible visual loss and systemic complications.