Granulomatosis with polyangiitis (GPA), formerly known as Wegener’s granulomatosis (WG), is an uncommon multisystem autoimmune disease that causes necrotizing granulomatosis, inflammation and pauciimmune vasculitis in small- and medium-sized blood vessels. The cause of GPA is unknown, although immunologic mechanisms play a role.
Typically, the upper and lower respiratory tract and the kidneys are affected, but any organ may be involved. Patients may present with upper and lower respiratory tract symptoms (e.g., recurrent nasal discharge or epistaxis, cough), followed by hypertension and oedema, or with symptoms reflecting multi-organ involvement. Diagnosis usually requires biopsy.
Routine laboratory tests in suspected granulomatosis with polyangiitis include ESR, CRP among others, and urinalysis. Serologic testing to detect antineutrophil cytoplasmic antibodies, ANCA, is followed by enzyme-linked immunosorbant assay (ELISA) to check for specific antibodies. Most patients with active GPA show cytoplasmic ANCA (cANCA), with proteinase 3 antibodies (anti-PR3).