A Case Report and Brief Literature Review of Cerebrospinal Fluid Rhinorrhea in Granulomatosis With Polyangiitis: A Rare Complication.

Granulomatosis with polyangiitis (GPA) is a necrotizing small-vessel vasculitis characterized by granulomatous inflammation and antineutrophil cytoplasmic antibody (ANCA) positivity. Sinonasal involvement is common, but cerebrospinal fluid (CSF) rhinorrhea is exceedingly rare. We present a rare case of a 44-year-old woman with established GPA who developed CSF rhinorrhea secondary to erosion of the cribriform plate. Her initial disease manifestations included episcleritis, septal perforation, atrophic turbinates, and saddle-nose deformity, with high PR3-ANCA titers and biopsy-proven small-vessel vasculitis. After achieving remission on corticosteroids and methotrexate, she presented four years later with watery nasal discharge that was triggered by bending forward. CT cisternography confirmed a CSF leak originating from a defect in the right anterior cribriform plate. She underwent successful endoscopic surgical repair using tensor fascia lata grafting, followed by immunosuppressive therapy and clinical improvement. This report highlights the potential for localized erosive disease in GPA despite apparent systemic remission and underscores the importance of timely recognition and multidisciplinary management.