title: Eosinophilic granulomatosis with polyangiitis (Churg-Strauss): evolutions in classification, etiopathogenesis, assessment and management.
abstract: OBJECTIVE
  Eosinophilic granulomatosis with polyangiitis (EGPA) (Churg-Strauss syndrome) is a peculiar hybrid condition of a systemic antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis and a hypereosinophilic disorder with frequent lung involvement that occurs in people with asthma. This review focuses on areas of evidence or persistent uncertainty in the classification, epidemiology, clinical presentation, diagnosis, prognosis and management of EGPA and attempts to identify clues to the mechanisms in the development or course of the disease.
  
  
  RESULTS
  The 2013 revision of the EGPA definition formally placed the disease in the subset of ANCA-associated vasculitides. Recently published large case series underlined that the presence of ANCAs, found in 30-40% of EGPA, determines distinct but partly overlapping disease expression and the major detrimental effect of heart involvement on survival. There is some evidence that asthma in EGPA resembles a nonallergic eosinophilic asthma phenotype. Encouraging results have been reported for the treatment of EGPA with rituximab or with the eosinophil-targeted antiinterleukin-5 agent mepolizumab.
  
  
  CONCLUSIONS
  The understanding of EGPA continues to advance, but many gaps in knowledge remain. The nomenclature remains a source of conceptual variance in terms of demonstrated presence or not of vessel inflammation or ANCAs in the diagnosis of EGPA. Distinguishing EGPA from hypereosinophilic syndromes can be problematic, and an understanding of the mechanistic relation between the vasculitis and the eosinophilic proliferation is profoundly lacking. Some evidence suggests distinct disease phenotypes, but this concept has not yet been translated to phenotype-adapted therapy.
authors.affiliation: aDepartment of Internal Medicine, Hospital Saint-Louis, University Paris Diderot, Paris, France bKlinikum Bad Bramstedt, Universitätsklinikum Schleswig-Holstein, Bad Bramstedt cDepartment of Internal Medicine 3, Jena University Hospital, Jena, Germany dDepartment of Medicine, Jagiellonian University Medical College, Krakow, Poland eDepartment of Pulmonology, Hospital Bichat, University Paris Diderot, Paris, France fUnit of Nephrology, University Hospital of Parma, Parma, Italy gLudwig Boltzmann Institute of Osteology at the Hanusch Hospital of WGKK and AUVA Trauma Centre Meidling, 1st Medical Department, Hanusch Hospital, Vienna, Austria.
authors.forename: Alfred
authors.initials: A
authors.lastname: Mahr
authors.forename: Frank
authors.initials: F
authors.lastname: Moosig
authors.forename: Thomas
authors.initials: T
authors.lastname: Neumann
authors.forename: Wojciech
authors.initials: W
authors.lastname: Szczeklik
authors.forename: Camille
authors.initials: C
authors.lastname: Taillé
authors.forename: Augusto
authors.initials: A
authors.lastname: Vaglio
authors.forename: Jochen
authors.initials: J
authors.lastname: Zwerina
mesh_terms: D001249:Asthma / Q000150:complications; D015415:Biomarkers / Q000097:blood; D015267:Churg-Strauss Syndrome / Q000175:diagnosis* / Q000188:drug therapy / Q000453:epidemiology / Q000209:etiology; D003937:Diagnosis, Differential; D005938:Glucocorticoids / Q000627:therapeutic use; D006801:Humans; D006967:Hypersensitivity / Q000150:complications; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D011379:Prognosis; D009626:Terminology as Topic
chemical_list: D015415:Biomarkers; D005938:Glucocorticoids; D007166:Immunosuppressive Agents