title: Pan-nephritis (glomerulonephritis, arteriolitis, and tubulointerstitial nephritis) associated with predominant mesangial C1q deposition and hypocomplementemia: a variant type of C1q nephropathy?
abstract: A 35-year-old man showed acute nephritic syndrome manifested as proteinuria, hematuria, and hypocomplementemia after upper respiratory infection. A renal biopsy showed mild to moderate mesangial proliferative glomerulonephritis with an accumulation of mononuclear cells in the capillary loop and with the deposition of C1q (graded as 3+), immunoglobulin (Ig) G, C3 (2+), IgA, IgM, and fibrinogen (weak to 1+), and mononuclear cell infiltration of the glomerular hilus, arterioles, and proximal tubules, which was a peculiar form of renal lesion. The mesangial deposition of C1q has been well documented in lupus nephritis, membranoproliferative glomerulonephritis, and endocapillary glomerulonephritis. The clinical signs and laboratory data in our patient ruled out these diseases. Although an immunofluorescence study showed these similarities to Clq nephropathy, the histopathological features of the peculiar arteriolitis and tubulointerstitial nephritis and laboratory findings of hypocomplementemia, as well as the good response to oral steroid therapy, differed from typical C1q nephropathy. The current patient appears to be a very rare phenotype of nephritis, being the only 1 case in almost 2,800 renal biopsies.
authors.affiliation: Third Department of Internal Medicine, Akita University Schoool of Medicine, Akita City, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Imai
authors.forename: T
authors.initials: T
authors.lastname: Yasuda
authors.forename: K
authors.initials: K
authors.lastname: Satoh
authors.forename: A B
authors.initials: AB
authors.lastname: Miura
authors.forename: T
authors.initials: T
authors.lastname: Sugawara
authors.forename: Y
authors.initials: Y
authors.lastname: Nakamoto
mesh_terms: D000328:Adult; D001160:Arterioles; D001167:Arteritis / Q000175:diagnosis*; D001706:Biopsy; D015922:Complement C1q / Q000032:analysis*; D003176:Complement C3 / Q000032:analysis; D003937:Diagnosis, Differential; D005340:Fibrinogen / Q000032:analysis; D005920:Glomerular Mesangium / Q000276:immunology*; D015432:Glomerulonephritis, Membranoproliferative / Q000175:diagnosis*; D006801:Humans; D007070:Immunoglobulin A / Q000032:analysis; D007074:Immunoglobulin G / Q000032:analysis; D007075:Immunoglobulin M / Q000032:analysis; D007668:Kidney / Q000098:blood supply* / Q000473:pathology; D008297:Male; D009395:Nephritis, Interstitial / Q000175:diagnosis*; D010641:Phenotype; D013577:Syndrome
chemical_list: D003176:Complement C3; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D015922:Complement C1q; D005340:Fibrinogen