title: Phospholipase A2 receptor staining in pediatric idiopathic membranous glomerulopathy.
abstract: BACKGROUND
  Membranous glomerulopathy, though typically a disease of adults, does occur in children. Antiphospholipase A2 receptor (PLA2R) autoantibodies have recently been implicated as a causative agent in most cases of adult primary (idiopathic) membranous glomerulopathy. PLA2R staining of renal biopsies in two recent large case series of adults with primary membranous glomerulopathy showed a sensitivity of approximately 75 % for detecting primary membranous glomerulopathy. To our knowledge, this is the largest study of its kind to assess PLA2R staining in a pediatric population.
  
  
  METHODS
  Forty-one consecutive cases of pediatric membranous glomerulopathy were identified from our database, and clinical follow-up was performed to confirm primary membranous glomerulopathy. Twenty-two patients met inclusion criteria and are the subject of this report.
  
  
  RESULTS
  Granular, capillary loop immunofluorescence staining for immunoglobulin G (IgG) was present in 100 % of patients, and C3 staining was present in 77 %. PLA2R staining was identified in ten patients, providing a sensitivity of 45 % [confidence interval (CI) 25-67 %]. Bovine serum albumin staining was performed in all PLA2R-negative cases and showed no positivity. Morphologic findings associated with negative PLA2R staining included segmental membranous lesions, mesangial and subendothelial deposits, C1q and "full-house" staining, and lower-stage lesions by electron microscopy. At 38 months' average follow-up, all patients were still considered as having primary membranous glomerulopathy, with none developing a clinically detectable secondary etiology.
  
  
  CONCLUSIONS
  PLA2R staining sensitivity is much lower in the pediatric than the adult primary membranous glomerulopathy population. This finding suggests a more diverse and currently incompletely described set of etiologies for this disease in this group.
authors.affiliation: Nephropath, 10810 Executive Center Dr. Suite 100, Little Rock, AR, 72211, USA, nich.cossey@nephropath.com.
authors.forename: L Nicholas
authors.initials: LN
authors.lastname: Cossey
authors.forename: Patrick D
authors.initials: PD
authors.lastname: Walker
authors.forename: Chris P
authors.initials: CP
authors.lastname: Larsen
mesh_terms: D000293:Adolescent; D000367:Age Factors; D015415:Biomarkers / Q000032:analysis; D001706:Biopsy; D002648:Child; D002675:Child, Preschool; D015922:Complement C1q / Q000032:analysis; D003176:Complement C3 / Q000032:analysis; D005260:Female; D005455:Fluorescent Antibody Technique; D015433:Glomerulonephritis, Membranous / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis; D007668:Kidney / Q000737:chemistry* / Q000276:immunology / Q000473:pathology; D008297:Male; D011237:Predictive Value of Tests; D011379:Prognosis; D054507:Receptors, Phospholipase A2 / Q000032:analysis*; D012307:Risk Factors; D013997:Time Factors
chemical_list: D015415:Biomarkers; D003176:Complement C3; D007074:Immunoglobulin G; C516360:PLA2R1 protein, human; D054507:Receptors, Phospholipase A2; D015922:Complement C1q
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