title: The clinical and pathological characteristics of nephropathies in connective tissue diseases in the Japan Renal Biopsy Registry (J-RBR).
abstract: BACKGROUND
  In connective tissue diseases, a wide variety of glomerular, tubulointerstitial, and vascular lesions of the kidney are observed. Nonetheless, recent information is limited regarding renal lesions in connective tissue diseases, except in systemic lupus erythematosus (SLE).
  
  
  METHODS
  In this study, we used a nationwide database of biopsy-confirmed renal diseases in Japan (J-RBR) (UMIN000000618). In total, 20,523 registered patients underwent biopsy between 2007 and 2013; from 110 patients with connective tissue diseases except SLE, we extracted data regarding the clinico-pathological characteristics of the renal biopsy.
  
  
  RESULTS
  Our analysis included patients with rheumatoid arthritis (RA) (n = 52), Sjögren's syndrome (SjS) (n = 35), scleroderma (n = 10), mixed connective tissue disease (MCTD; n = 5), anti-phospholipid syndrome (APS; n = 3), polymyositis/dermatomyositis (PM/DM; n = 1), Behçet's disease (n = 1) and others (n = 3). The clinico-pathological features differed greatly depending on the underlying disease. The major clinical diagnosis was nephrotic syndrome in RA; chronic nephritic syndrome with mild proteinuria and reduced renal function in SjS; rapidly progressive nephritic syndrome in scleroderma. The major pathological diagnosis was membranous nephropathy (MN) and amyloidosis in RA; tubulointerstitial nephritis in SjS; proliferative obliterative vasculopathy in scleroderma; MN in MCTD. In RA, most patients with nephrosis were treated using bucillamine, and showed membranous nephropathy.
  
  
  CONCLUSIONS
  Using the J-RBR database, our study revealed that biopsy-confirmed cases of connective tissue diseases such as RA, SjS, scleroderma, and MCTD show various clinical and pathological characteristics, depending on the underlying diseases and the medication used.
authors.affiliation: Department of Cardiology, Pulmonology, and Nephrology, Yamagata University School of Medicine, 2-2-2, Iida-Nishi, Yamagata, 990-9585, Japan.
authors.forename: Kazunobu
authors.initials: K
authors.lastname: Ichikawa
authors.affiliation: Department of Cardiology, Pulmonology, and Nephrology, Yamagata University School of Medicine, 2-2-2, Iida-Nishi, Yamagata, 990-9585, Japan. kkonta@med.id.yamagata-u.ac.jp.
authors.forename: Tsuneo
authors.identifier: http://orcid.org/0000-0001-7681-6469
authors.initials: T
authors.lastname: Konta
authors.affiliation: Clinical Pharmacology and Therapeutics, Tohoku University Graduate School of Pharmaceutical Sciences, Sendai, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sato
authors.affiliation: Department of Pathology, Dokkyo Medical University Koshigaya Hospital, Koshigaya, Japan.
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Ueda
authors.affiliation: Division of Nephrology, Kanazawa Medical University School of Medicine, Uchinada, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Yokoyama
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D003240:Connective Tissue Diseases / Q000150:complications*; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D007668:Kidney / Q000473:pathology*; D007674:Kidney Diseases / Q000453:epidemiology / Q000209:etiology* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D012042:Registries; D055815:Young Adult
keywords: Connective tissue disease; Renal biopsy; Rheumatoid arthritis; Scleroderma; Sjögren’s syndrome