Wegener's Granulomatosis, now known as Granulomatosis with Polyangiitis, is a rare autoimmune disease that causes inflammation of blood vessels, leading to reduced blood flow to various organs. It primarily affects the respiratory system, kidneys, and sinuses, resulting in symptoms like sinusitis, cough, and kidney dysfunction. The exact cause of Granulomatosis with Polyangiitis is unknown, but it involves an abnormal immune response. Diagnosis typically includes blood tests, imaging studies, and sometimes a biopsy. Treatment often involves medications to suppress the immune system, such as corticosteroids and immunosuppressants, to manage symptoms and prevent complications.