Eosinophilic granulomatosis with polyangiitis (EGPA—formerly known as Churg-Strauss syndrome) is a systemic small- and medium-vessel necrotizing vasculitis, characterized by extravascular granulomas, eosinophilia, and tissue infiltration by eosinophils. It occurs in people with adult-onset asthma, allergic rhinitis, nasal polyposis, or a combination. Diagnosis is best confirmed by biopsy. Treatment is primarily with corticosteroids and, for severe disease, addition of other immunosuppressants.
EGPA occurs in about 3 people/million. Mean age at onset is 48.
EGPA is characterized by extravascular necrotizing granulomas (usually rich in eosinophils), eosinophilia, and tissue infiltration by eosinophils. However, these abnormalities do not always coexist. The vasculitis typically affects small- and medium-sized arteries. Any organ can be affected, but the lungs, skin, sinuses, cardiovascular system, kidneys, peripheral nervous system, CNS, joints, and GI tract are most commonly affected. Occasionally, pulmonary capillaritis may cause alveolar hemorrhage.
The cause is unknown. However, an allergic mechanism, with tissue directly injured by eosinophils and neutrophil degranulation products, may be involved. Activation of T lymphocytes seems to help maintain eosinophilic inflammation. The syndrome occurs in patients who have adult-onset asthma, allergic rhinitis, nasal polyposis, or a combination. Antineutrophil cytoplasmic autoantibodies (ANCA) are present in about 40% of cases.
Symptoms and Signs
The syndrome has 3 phases, which may overlap:
However, the phases do not necessarily follow one another consecutively, and the time interval between them varies greatly.
Various organs and systems may be affected:
Renal, cardiac, or neurologic involvement indicates a worse prognosis.
The 2012 Chapel Hill Consensus Conference defined EGPA as an eosinophil-rich and necrotizing granulomatous inflammation involving the respiratory tract with necrotizing vasculitis of small- and medium-sized vessels in association with asthma and eosinophilia. Criteria for classification from the American College of Rheumatology consist of the following:
If ≥ 4 criteria are present, sensitivity is 85%, and specificity is 99.7%.
Testing aims to establish the diagnosis and the extent of organ involvement and to distinguish EGPA from other eosinophilic disorders (eg, parasitic infections, drug reactions, acute and chronic eosinophilic pneumonia, allergic bronchopulmonary aspergillosis, hypereosinophilic syndrome). Diagnosis is suggested by clinical findings and results of routine laboratory tests but should usually be confirmed by biopsy of lung or other affected tissue.
Blood tests and chest x-rays are done, but results are not diagnostic. CBC with differential is done to check for eosinophilia, which is also a marker of disease activity. IgE and C-reactive protein levels and ESR are determined periodically to evaluate inflammatory activity. Urinalysis and creatinine are done to screen for renal disease and monitor its severity. Electrolyte levels are measured.
Serologic testing is done and detects ANCA in up to 40% of patients; if ANCA is detected, enzyme-linked immunosorbent assay (ELISA) is done to check for specific antibodies. Perinuclear ANCA (p-ANCA) with antibodies against myeloperoxidase is the most common result, but ANCA is not a specific or sensitive test for EGPA.
Chest x-ray often shows transient patchy pulmonary infiltrates.
Biopsy of the most accessible affected tissue should be done if possible.
Systemic corticosteroids are the mainstay of treatment. However, corticosteroids alone often do not maintain remission, even if there are no poor prognostic factors. Other immunosuppressants may be added, depending on the severity and the type of organ involvement, using the same general criteria for treatment of granulomatosis with polyangiitis (see see Granulomatosis with Polyangiitis (GPA)) or microscopic polyangiitis (see see Microscopic Polyangiitis (MPA)).
Last full review/revision April 2013 by Carmen E. Gota, MD
Content last modified September 2013