Granulomatosis with Polyangiitis in Otolaryngology – Diagnosis, Differential Diagnosis, and Modern Treatment Techniques

<b>Introduction:</b> Granulomatosis with polyangiitis (GPA) is a rare, multi-organ autoimmune disease characterized by necrotizing inflammation predominantly affecting small- and medium-sized blood vessels, often leading to severe complications. In most GPA patients, otolaryngological symptoms are evident at the time of presentation to a physician.<b>Aim:</b> This study aims to review the diagnosis, differential diagnosis, and modern treatment methods for GPA, particularly from an otolaryngological perspective.<b>Materials and methods:</b> A comprehensive review of current scientific literature was conducted using PubMed and Google Scholar databases, focusing on articles published between 2016 and 2025. A critical evaluation of diagnostic methods, including ANCA antibody detection, imaging studies, and histopathology, was performed. The efficacy of immunosuppressive and biological therapies was also assessed.<b>Results:</b> GPA most commonly presents with sinonasal symptoms, such as chronic nasal discharge, epistaxis, and, in severe cases, nasal deformities like septal perforation or saddle-nose deformity. Diagnosis relies on detecting PR3-ANCA antibodies and histopathologically confirming granulomas with vascular necrosis. Treatment involves glucocorticosteroids and immunosuppressive agents, such as cyclophosphamide and rituximab, which achieve remission in most patients. Modern biological therapies, including interleukin-5 inhibitors, show promising results in refractory disease cases.<b>Conclusions:</b> Granulomatosis with polyangiitis remains a diagnostic and therapeutic challenge. Early recognition of otolaryngological symptoms and a multidisciplinary approach to treatment are crucial for improving patient outcomes. Advances in modern therapeutic approaches, such as rituximab and mepolizumab, have significantly improved prognosis and quality of life for patients, although disease relapses remain a considerable challenge.