Membranous Nephropathy with Proteinase 3-ANCA-associated Vasculitis Successfully Treated with Rituximab

Membranous nephropathy (MN) with anti-neutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis (ANCA-GN) is seen infrequently. Previous reports of patients with ANCA-GN with MN showed that the most frequent ANCA subtype was myeloperoxidase-ANCA. We herein present a 73-year-old woman with scleritis, hematuria, proteinuria, and positive serum proteinase 3 (PR3)-ANCA. She underwent a renal biopsy and was diagnosed with MN and ANCA-GN. Immunofluorescence staining for PR3 colocalized with IgG along the glomerular basement membrane were observed. Oral prednisolone and intravenous rituximab therapy immediately improved her symptoms and urinalysis abnormalities. PR3-ANCA may be involved in the pathogenesis of MN via the formation of immune complexes.