Churg-Strauss angiitis

Churg-Strauss angiitis or syndrome (CSA) is defined as an eosinophil-rich and granulomatous inflammation involving the respiratory tract, and necrotising vasculitis affecting small- to medium-sized vessels, and is associated with asthma and eosinophilia. It is usually classified among the so-called anti-neutrophil antibody (ANCA)-associated systemic vasculitides (AASVs) because of its clinical and pathological features that overlap with those of the other AASVs. However, two recent studies on large cohorts of patients have found that ANCAs, usually P-ANCAs/MPO-ANCAs, were present in only 38% of patients. Moreover, the ANCA status was shown to segregate with clinical phenotype. ANCA-positive patients were significantly more likely to have disease manifestations associated with small-vessel vasculitis, including necrotising glomerulonephritis, mononeuritis and purpura, whereas ANCA-negative cases were significantly more likely to have cardiac and lung involvement. Vasculitis was documented less frequently in histological specimens from ANCA-negative patients in comparison with ANCA-positive ones. These findings have led to postulate the predominance of distinct pathogenetic mechanisms in the two subsets of patients: an ANCA-mediated process in ANCA-positive patients and tissue infiltration by eosinophils with subsequent release of toxic product in ANCA-negative cases. Preliminary results suggest that ANCA-positive and ANCA-negative patients also might have a different genetic background. Corticosteroids remain the cornerstone of the initial treatment of CSA. The addition of cyclophosphamide is indicated in treatment of patients with poor-prognosis factors or in patients without poor-prognosis factors but those that are prone to relapses. The length of the maintenance therapy remains to be established. However, the vast majority of patients require long-term corticosteroids treatment to control asthma.