text: Diagnosis Diagnostic markers include eosinophil granulocytes and granulomas in affected tissue, and antineutrophil cytoplasmic antibodies (ANCA) against neutrophil granulocytes. Two pathological subsets of EGPA are differentiated by the presence of antineutrophil cytoplasmic antibodies (ANCA), autoantibodies that mistakenly target and attack specific proteins found within the cytoplasm of neutrophils. The ANCA+ subtype is characterized by predominantly vasculitis-like manifestations, while the ANCA- subtype is more commonly associated with eosinophilic-related symptoms. Approximately 30-40% of EGPA cases are ANCA+. While the pathogenic mechanisms are not fully understood, this finding suggests a role of B cells – the precursors of ANCA-producing plasma cells – in the pathogenesis of EGPA.
  The American College of Rheumatology 1990 criteria for diagnosis of Churg–Strauss syndrome lists these criteria:
  Asthma
  Eosinophilia, i.e. eosinophil blood count greater than 500/microliter, or hypereosinophilia, i.e. eosinophil blood count greater than 1,500/microliter
  Presence of mononeuropathy or polyneuropathy
  Unfixed pulmonary infiltrates
  Presence of paranasal sinus abnormalities
  Histological evidence of extravascular eosinophils
  For classification purposes, a patient shall be said to have EGPA if at least four of these six criteria are positive. The presence of any four or more of the six criteria yields a sensitivity of 85% and a specificity of 99.7%.
  Risk stratification
  The French Vasculitis Study Group has developed a five-point system ("five-factor score") that predicts the risk of death in Churg–Strauss syndrome using clinical presentations. These factors are: