Granulomatosis with Polyangiitis (GPA) in a Polish Tertiary Centre (2010–2025): Sex-Stratified Phenotypes, Serology, and Evolving Treatment Patterns

<b>Background/Objectives</b>: GPA is a PR3-ANCA-predominant small vessel vasculitis with organ involvement. Real-world, single-centre data are needed to interpret evolving therapies and phenotype patterns in national conditions. <b>Material and Methods</b>: Retrospective cohort study of consecutive GPA patients managed at the National Institute of Geriatrics, Rheumatology and Rehabilitation (Warsaw, Poland) from 1 September 2010 to 1 September 2025. Data included demographics, phenotype, BVAS, organ involvement, PR3/MPO-ANCA serology, and induction/maintenance therapies. <b>Results</b>: Fifty patients were included (54.0% men). Mean age was 52.5 years; mean BMI was 26.15 kg/m². Ear-nose-throat (ENT) disease was frequent: rhinosinusitis 76.0%, nasal cartilage destruction 64.0%, subglottic stenosis 34.0%. Pulmonary nodules occurred in 52.0%, cavitation in 28.0%, and diffuse alveolar haemorrhage in 34.0%. Renal involvement included haematuria in 42.0%, chronic kidney disease (CKD) in 32.0%, and rapidly progressive kidney disease in 22.0%. Orbital inflammation was 36.0%, and PR3-ANCA was positive in 70.0%. All patients received glucocorticoids for induction; cyclophosphamide 28/50 (56.0%), rituximab 6/50 (12.0%), and mycophenolate with methotrexate 6/50 (32%). Maintenance therapy included methotrexate (78.0%), mycophenolate (64.0%), rituximab (52.0%), and azathioprine (12.0%). <b>Conclusions</b>: This Polish single-centre cohort shows an ear-nose-throat-lung-kidney (ELK)-dominant, PR3-predominant GPA phenotype and frequent but variable kidney involvement. Over 2010-2025, practice changed toward rituximab-based strategies, steroid minimisation, selective use of plasma exchange, and early avacopan uptake, with tofacitinib for maintenance therapy as a possible new therapeutic option.