title: Proposal for diagnostic criteria for IgG4-related kidney disease.
abstract: BACKGROUND
  IgG4-related disease has attracted wide attention recently. It is characterized by a high level of serum IgG4 and dense infiltration of IgG4-positive plasma cells into multiple organs, with the kidney being one representative target. Although several sets of diagnostic criteria for autoimmune pancreatitis (AIP) are available and renal lesion is recognized as an extra-pancreatic manifestation of AIP, it is difficult to differentiate IgG4-related tubulointerstitial nephritis (TIN) without AIP from other types of TIN. To clarify the entity of IgG4-related kidney disease (IgG4-RKD) and support in-depth studies, the Japanese Society of Nephrology has established a working group to prepare diagnostic criteria for IgG4-RKD.
  
  
  METHODS
  The working group analyzed 41 patients with IgG4-RKD, and collected the following data to devise a diagnostic algorithm and diagnostic criteria for IgG4-RKD: clinical features including extra-renal organ involvement, urinalysis and serological features including serum IgG4 levels, imaging findings demonstrated by computed tomography (CT), renal histology with IgG4 immunostaining, and response to steroid therapy.
  
  
  RESULTS
  The conditions for criteria are as follows. (1) Presence of some kidney damage, as manifested by abnormal urinalysis or urine marker(s) and/or decreased kidney function with either elevated serum IgG level, hypocomplementemia, or elevated serum IgE level. (2) Kidney imaging studies showing abnormal renal imaging findings, i.e., multiple low density lesions on enhanced CT, diffuse kidney enlargement, hypovascular solitary mass in the kidney, and hypertrophic lesion of the renal pelvic wall without irregularity of the renal pelvic surface. (3) Serum IgG4 level exceeding 135 mg/dl. (4) Renal histology showing two abnormal findings: (a) dense lymphoplasmacytic infiltration with infiltrating IgG4-positive plasma cells >10/high power field (HPF) and/or ratio of IgG4-positive plasma cells/IgG positive plasma cells >40%. (b) Characteristic 'storiform' fibrosis surrounding nests of lymphocytes and/or plasma cells. (5) Extra-renal histology showing dense lymphoplasmacytic infiltration with infiltrating IgG4-positive plasma cells >10/HPF and/or ratio of IgG4-positive plasma cells/IgG-positive plasma cells >40%. The diagnosis is classified into 3 stages of definite, probable and possible according to the combinations of the above conditions. Thirty-nine cases (95.1%) were diagnosed with IgG4-RKD according to the criteria.
  
  
  CONCLUSIONS
  The provisional criteria and algorithm appear to be useful for clarifying the entity of IgG4-RKD and seeking underlying IgG4-RKD cases; however, further experience is needed to confirm the validity of these criteria.
authors: Division of Rheumatology, Department of Internal Medicine, Kanazawa University Hospital, Kanazawa, Japan.
authors: Mitsuhiro
authors: M
authors: Kawano
authors: Department of Internal Medicine, Nagaoka Red Cross Hospital, Nagaoka, Japan.
authors: Takako
authors: T
authors: Saeki
authors: Division of Nephrology and Rheumatology, Department of Internal Medicine, Faculty of Medicine, Fukuoka University, 7-45-1 Nanakuma, Jonan-ku, Fukuoka, 814-0180, Japan.
authors: Hitoshi
authors: H
authors: Nakashima
authors: Division of Nephrology and Kidney Center, Kobe University Graduate School of Medicine, Kobe, Japan.
authors: Shinichi
authors: S
authors: Nishi
authors: Yamaguchi's Pathology Laboratory, Chiba, Japan.
authors: Yutaka
authors: Y
authors: Yamaguchi
authors: Department of Pathology, Faculty of Medicine, Fukuoka University, Fukuoka, Japan.
authors: Satoshi
authors: S
authors: Hisano
authors: Tokyo Kidney Research Institute, Tokyo, Japan.
authors: Nobuaki
authors: N
authors: Yamanaka
authors: Department of Radiology, Toyama Prefectural Central Hospital, Toyama, Japan.
authors: Dai
authors: D
authors: Inoue
authors: First Department of Internal Medicine, Sapporo Medical University School of Medicine, Sapporo, Japan.
authors: Motohisa
authors: M
authors: Yamamoto
authors: First Department of Internal Medicine, Sapporo Medical University School of Medicine, Sapporo, Japan.
authors: Hiroki
authors: H
authors: Takahashi
authors: Department of General Medicine, Kanazawa University Hospital, Kanazawa, Japan.
authors: Hideki
authors: H
authors: Nomura
authors: Department of Pathology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
authors: Takashi
authors: T
authors: Taguchi
authors: Department of Hematology and Immunology, Kanazawa Medical University, Ishikawa, Japan.
authors: Hisanori
authors: H
authors: Umehara
authors: Department of Medicine and Clinical Science, Okayama University Graduate School of Medicine, Okayama, Japan.
authors: Hirofumi
authors: H
authors: Makino
authors: Division of Nephrology and Rheumatology, Department of Internal Medicine, Faculty of Medicine, Fukuoka University, 7-45-1 Nanakuma, Jonan-ku, Fukuoka, 814-0180, Japan. tsaito@fukuoka-u.ac.jp.
authors: Takao
authors: T
authors: Saito
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D001327:Autoimmune Diseases / Q000175:diagnosis / Q000473:pathology; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D007150:Immunohistochemistry; D007668:Kidney / Q000473:pathology; D007674:Kidney Diseases / Q000175:diagnosis* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009395:Nephritis, Interstitial / Q000175:diagnosis* / Q000473:pathology; D010179:Pancreas / Q000473:pathology; D010195:Pancreatitis / Q000473:pathology; D014057:Tomography, X-Ray Computed
chemical_list: D007074:Immunoglobulin G