Abstract:

A 55yearold man presented with maransis,fatigue and weight loss.The laboratory tests demonstrated mild to moderate proteinuria,renal insufficiency,anemia,positive antiMPO antibodies and elevated serum IgG and IgG4 concentration.Imaging studies disclosed bilateral renal enlargement.A kidney biopsy was performed and showed acute interstitial nephritis and necrotizing vasculitis with granuloma.Immunohistochemical analysis exhibited 50 infiltrating IgG4positive plasma cells/high power field in the interstitum.Finally,the patient was diagnosed with granulomatosis with polyangiitis concomitant with IgG4related kidney disease.

Key words: granulomatosis with polyangiitis, IgG4-related kidney disease, renal biopsy