title: Proposal of podocytic infolding glomerulopathy as a new disease entity: a review of 25 cases from nationwide research in Japan.
abstract: BACKGROUND
  A rare and peculiar glomerulopathy has begun to be recognized in Japan. The Japanese Society of Nephrology has established a research working group and has collected cases from all over Japan in an attempt to understand the complete spectrum of this glomerulopathy.
  
  
  METHODS
  The diagnostic criterion, which was needed to collect the cases, was proposed as a glomerulopathy showing microspheres or microtubular structures or both associated with podocytic infolding into the glomerular basement membrane (GBM) on electron microscopy. The lesion shows a non-argentaffin hole in the GBM with periodic acid methenamine silver staining and is similar to membranous glomerulonephritis.
  
  
  RESULTS
  Twenty-five cases were collected from 17 institutions. Patients were 20-69 years old (19 women, 6 men). Seventeen patients also had collagen diseases such as lupus nephritis and Sjögren's syndrome. All patients had proteinuria. Proteinuria showed a remission in 15 of 23 patients within 12 months, but proteinuria remained higher than 1.0 g/day in five patients despite different types of therapy. Podocytic infolding including microspheres showed either positive or negative staining for immunoglobulins. Cluster formation of microspheres was found in 4 of 17 patients with collagen disease, and in five out eight patients without collagen disease. Electron-dense deposits in the GBM were also found in 6 of 17 patients with collagen disease but were not found in eight patients without collagen disease.
  
  
  CONCLUSIONS
  Some patients might have a subtype of lupus nephritis, class V, or membranous glomerulonephritis. However, we propose a new disease entity, podocytic infolding glomerulopathy, as a common basis of all 25 patients, because we suspect that microspheres or microtubular structures or both can be derived from podocytic infolding.
authors.affiliation: Division of Renal Pathology, Clinical Research Center, Chiba-East National Hospital, Chiba, 260-8712, Japan. johken@cehprinet.com
authors.forename: Kensuke
authors.initials: K
authors.lastname: Joh
authors.forename: Takashi
authors.initials: T
authors.lastname: Taguchi
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Shigematsu
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Kobayashi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sato
authors.forename: Shinichi
authors.initials: S
authors.lastname: Nishi
authors.forename: Ritsuko
authors.initials: R
authors.lastname: Katafuchi
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Nomura
authors.forename: Yoshihide
authors.initials: Y
authors.lastname: Fujigaki
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Utsunomiya
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Sugiyama
authors.forename: Takao
authors.initials: T
authors.lastname: Saito
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Makino
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D050533:Glomerular Basement Membrane / Q000473:pathology*; D006801:Humans; D007674:Kidney Diseases / Q000473:pathology*; D008297:Male; D008863:Microspheres; D008875:Middle Aged; D050199:Podocytes / Q000473:pathology*