Diagnosis and classification of eosinophilic granulomatosis with polyangiitis (formerly named Churg–Strauss syndrome)

Recently, a group of experts in the field suggested to rename Churg–Strauss syndrome as eosinophilic granulomatosis with polyangiitis (EGPA). This condition, first described in 1951, is a rare small- and medium-sized–vessel vasculitis characterized by an almost constant association with asthma and eosinophilia, and, by the presence of anti-myeloperoxidase (MPO) antineutrophil cytoplasm antibodies (ANCA) in 30–38% of the patients. Vasculitis typically develops in a previously asthmatic and eosinophilic middle-aged patient. Asthma is severe, associated with eosinophilia and extrapulmonary symptoms. Most frequently EGPA involves the peripheral nerves and skin. Other organs, however, may be affected and must be screened for vasculitis, especially those associated with a poorer prognosis, such as the heart, kidney and gastrointestinal tract, as assessed by the recently revised Five-Factor Score (FFS). Recent insights, particularly concerning clinical differences associated with ANCA status, showed that EGPA patients might constitute a heterogeneous group. Thus, EGPA patients with anti-MPO ANCA suffered more, albeit not exclusively, from vasculitis symptoms, such as glomerulonephritis, mononeuritis multiplex and alveolar hemorrhage, whereas ANCA-negative patients more frequently develop heart involvement. This observation led to the hypothesis that EGPA might be divided into different clinical and pathophysiological subtypes, which could be managed better with more specifically adapted therapies.For now, EGPA treatment still relies mainly on corticosteroids and, when necessary for patients with poorer prognoses, combined immunosuppressant drugs, especially cyclophosphamide. Overall survival of EGPA patients is good, despite not uncommon relapses.