Granulomatosis with polyangiitis (GPA) is a rare autoimmune disease of small vessels characterized by vessel inflammation (vasculitis) and granuloma formation, most commonly affecting the upper and lower respiratory tract and kidneys.[3] Many patients have autoantibodies called ANCA (antineutrophil cytoplasmic antibodies) in their blood, which are important for diagnosing and differentiating GPA from other forms of vasculitides.[3] Clinical manifestations include recurrent sinusitis, chronic rhinitis, cough, dyspnea, pulmonary infiltrates, and blood in the urine with renal involvement.[3] The diagnosis is based on a combination of the clinical picture, the finding of ANCA antibodies, imaging studies and histological evidence of vasculitis or granulomas in the affected tissue.[3] Treatment consists of suppressing the immune response, mainly with glucocorticoids in combination with immunosuppressants or biological therapy, with the aim of achieving remission and reducing the risk of organ damage.[3] Prognosis has improved significantly in recent decades due to early diagnosis and standardized treatment procedures, although the disease often has a chronic, relapsing course.[3]