title: IgG4-related periaortitis vs idiopathic periaortitis: is there a role for atherosclerotic plaque in the pathogenesis of IgG4-related periaortitis?
abstract: OBJECTIVE
  The diagnosis of (isolated) IgG4-related periaortitis is often based on elevated serum IgG4 levels since in tissues such as the aorta, biopsies cannot be easily performed. However, the role for serum IgG4 as a biomarker for IgG4-related periaortitis is indistinct. The main purpose of our study was to identify clinical differences between periaortitis with elevated vs normal serum IgG4 levels.
  
  
  METHODS
  A retrospective study was performed on 68 non-infectious periaortitis patients. We compared demographic, clinical, biochemical and radiological data in patients with elevated serum IgG4 levels with data from patients with normal serum IgG4 levels. The calcium content of the aortic wall was calculated to determine the amount of atherosclerosis.
  
  
  RESULTS
  After applying exclusion criteria, our study population consisted of nine IgG4-related periaortitis patients and eight idiopathic periaortitis patients. Striking significant differences were male predominance (P = 0.001) and multifocal organ involvement (P = 0.004) in IgG4-related periaortitis patients compared with the idiopathic periaortitis group. The calcium content of the total aortic wall was significantly higher in IgG4-related periaortitis patients (P = 0.005). No other significant differences were found.
  
  
  CONCLUSIONS
  Elevated serum IgG4 levels, male gender, a higher calcium content of the aortic wall and multifocal organ involvement are features that might provide a higher probability for IgG4-related periaortitis compared with idiopathic periaortitis. Our study results might be compatible with the hypothesis of Mitchinson and Parums that atherosclerotic plaque plays a role in the pathogenesis of chronic periaortitis.
authors.affiliation: Department of General Internal Medicine and Department of Radiology, University Hospital Gasthuisberg, Leuven, Belgium thomas.castelein@student.kuleuven.be.
authors.forename: Thomas
authors.initials: T
authors.lastname: Castelein
authors.affiliation: Department of General Internal Medicine and Department of Radiology, University Hospital Gasthuisberg, Leuven, Belgium.
authors.forename: Walter
authors.initials: W
authors.lastname: Coudyzer
authors.affiliation: Department of General Internal Medicine and Department of Radiology, University Hospital Gasthuisberg, Leuven, Belgium.
authors.forename: Daniel
authors.initials: D
authors.lastname: Blockmans
mesh_terms: D000328:Adult; D000368:Aged; D001011:Aorta / Q000737:chemistry; D001323:Autoantibodies / Q000502:physiology; D015415:Biomarkers / Q000097:blood; D002118:Calcium / Q000032:analysis; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D058226:Plaque, Atherosclerotic / Q000097:blood / Q000503:physiopathology*; D012185:Retroperitoneal Fibrosis / Q000097:blood / Q000276:immunology* / Q000503:physiopathology*; D012189:Retrospective Studies; D012720:Severity of Illness Index; D012737:Sex Factors
chemical_list: D001323:Autoantibodies; D015415:Biomarkers; D007074:Immunoglobulin G; D002118:Calcium
keywords: IgG4-related disease; IgG4-related periaortitis; atherosclerosis; chronic periaortitis; idiopathic periaortitis; inflammatory abdominal aortic aneurysm; retroperitoneal fibrosis