ChurgStrauss

Churg-Strauss syndrome, now commonly called eosinophilic granulomatosis with polyangiitis (EGPA), is a rare systemic vasculitis that affects small- to medium-sized vessels. It is one of the anti-neutrophil cytoplasmic antibody (ANCA)–associated vasculitides and is characterized by eosinophil-rich inflammation and granulomatous tissue involvement. The disease often progresses through phases, starting with allergic features and peripheral eosinophilia, followed by vasculitic manifestations.

Clinical features typically begin with adult-onset asthma and allergic rhinitis, accompanied by marked eosinophilia. As the disease evolves, patients may develop systemic vasculitis with neuropathy (often mononeuritis multiplex), skin findings such as palpable purpura, sinusitis, pulmonary infiltrates or nodules, and cardiac involvement including myocarditis or heart failure. Renal involvement is less common than in other ANCA-associated vasculitides but can occur; gastrointestinal symptoms may also be present.

Diagnosis relies on a combination of clinical features, laboratory tests, and often biopsy. The American College of Rheumatology criteria (historically used) require four of six features: asthma, eosinophilia greater than 10%, neuropathy, pulmonary infiltrates, paranasal sinus abnormalities, and extravascular eosinophils on biopsy. ANCA positivity, particularly p-ANCA (MPO-ANCA), is detected in a substantial minority of patients, though its absence does not exclude EGPA. Imaging and tissue biopsy support the diagnosis and help assess organ involvement.

Treatment centers on systemic corticosteroids; immunosuppressive therapy such as cyclophosphamide or rituximab is added for organ-threatening disease or poor response. Maintenance therapy may include azathioprine or methotrexate, and targeted biologics like mepolizumab (anti-IL-5) have shown benefit. Prognosis has improved with early recognition and treatment, though relapse can occur and cardiac involvement is a major determinant of outcome.

Churg-Strauss was named after Jacob Churg and Lotte Strauss, who first described the condition in 1951.