Chug strauss syndrome

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"eosinophilic granulomatosis with polyangiitis" OR "Churg-Strauss"

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Churg-Strauss Syndrome (Eosinophilic Granulomatosis with Polyangiitis - EGPA)

First described by Churg and Strauss in 1951, this is a systemic necrotizing vasculitis affecting small- and medium-sized vessels, characterized by the triad of asthma, peripheral eosinophilia, and extravascular granulomas.

Epidemiology

Annual incidence: 1-3 per million (uncommon)
Mean age of onset: 48 years (but can occur at any adult age)
Female-to-male ratio: 1.2:1 (slight female predominance)

Three Classic Phases

Phase	Features	Duration
1. Allergic (Prodromal)	Asthma, allergic rhinitis, nasal polyps	Often years; avg asthma onset at 35 yrs
2. Eosinophilic	Fever, peripheral eosinophilia (20-90%), eosinophilic pneumonia and gastroenteritis	Months to years
3. Vasculitic	Systemic small- and medium-vessel vasculitis with granulomatous inflammation - avg ~3 yrs after onset	-

The vasculitic phase involves the lungs, heart, liver, spleen, kidneys, intestines, and pancreas. - Andrews' Diseases of the Skin, p. 4684

Triggers of the vasculitic phase include vaccination, desensitization, leukotriene inhibitors, azithromycin, inhaled fluticasone, and rapid corticosteroid discontinuation.

Pathology

Necrotizing vasculitis of small- and medium-sized muscular arteries, capillaries, veins, and venules
Extravascular granulomas - a hallmark; may occur within vessel walls
Tissue eosinophil infiltration
Palisaded granulomas differ from GPA (Wegener's): they generally lack multinucleated giant cells and have an eosinophil-rich core
"Flame figures" similar to Wells syndrome may be seen in dermis

Clinical Manifestations

Systemic: Fever, malaise, anorexia, weight loss

Pulmonary (dominant):

Asthmatic attacks
Non-fixed migratory pulmonary infiltrates

Neurological:

Mononeuritis multiplex - second most common manifestation, occurs in up to 72% of patients

ENT:

Allergic rhinitis and sinusitis in up to 61% of patients

Cardiac (most important for mortality):

Myocarditis, pericarditis, endocarditis, or coronary vasculitis in ~14% of patients
Congestive heart failure from granulomatous myocardial inflammation is the most frequent cause of death (responsible for 39% of mortality)

Skin (present in ~51-67% of patients):

Palpable purpura (~50%)
Subcutaneous nodules on extensor surfaces and scalp (~30%)
Firm, nontender papules on fingertips (may mimic septic emboli)
Urticaria, livedo reticularis, Wells syndrome-like plaques

Renal:

Less common than in GPA or microscopic polyangiitis

Laboratory Findings

Finding	Detail
Eosinophilia	Present in virtually ALL patients; >1000 cells/µL in >80%
ANCA	Positive in ~48% (Harrison's) to 55-70% (Andrews'); usually p-ANCA / anti-MPO
ESR/CRP/fibrinogen	Elevated in ~81%

ACR 1990 Classification Criteria

Diagnosis requires ≥4 of 6 criteria:

Asthma - history of wheezing or high-pitched expiratory rales
Eosinophilia >10% on WBC differential
Mononeuropathy or polyneuropathy attributable to vasculitis
Non-fixed pulmonary infiltrates - migratory/transitory infiltrates on CXR
Paranasal sinus abnormality - pain, tenderness, or radiographic opacification
Extravascular eosinophils on biopsy (artery, arteriole, or venule)

Source: Rheumatology 2-Volume Set (2022, Elsevier), p. 6513-6527

Diagnosis

Optimally made by biopsy + characteristic clinical features
Histologic confirmation is challenging because pathognomonic features often do not occur simultaneously
Minimum diagnostic requirement: asthma + peripheral eosinophilia + clinical features consistent with vasculitis
Echocardiography should be performed in ALL newly diagnosed patients (cardiac involvement affects prognosis and treatment decisions)

Treatment

Stratification by Severity (Five Factor Score - FFS)

FFS = 0 (low risk): Corticosteroids alone (prednisone ~1 mg/kg/day)

FFS ≥ 1 (high risk) / Fulminant disease: Cyclophosphamide + prednisone, then switch to azathioprine or methotrexate for maintenance

Indications for cyclophosphamide: neuropathy, refractory glomerulonephritis, myocardial disease, severe GI disease, CNS involvement

Biologic therapy:

Mepolizumab (anti-IL-5 antibody, 300 mg SC monthly) - approved for non-life-threatening EGPA; shown to be more effective than placebo (remission 32% vs 3%); beneficial in relapsing/refractory asthma, sinus disease, mild vasculitis. [Updated 2025 systematic review - PMID 40766318]
Benralizumab (also anti-IL-5R) - a recent study showed non-inferior remission rates compared to mepolizumab in relapsing/refractory non-life-threatening EGPA
Rituximab - consider in ANCA-positive patients with glomerulonephritis or severe small-vessel vasculitis features

Steroid-sparing maintenance: Azathioprine, methotrexate, leflunomide

Other reported agents: IFN-α, MMF, IVIG, leukotriene-receptor antagonists, infliximab, etanercept

Prognosis

Untreated: 5-year survival ~25% (poor)
With treatment: ~90% survival at 7 years (good, when properly stratified)
~40% of patients experience one or more relapses, usually with steroid taper
Leading cause of death: congestive heart failure from cardiac granulomatous involvement

Key Differences from Other ANCA Vasculitides

Feature	EGPA (CSS)	GPA (Wegener's)	MPA
Asthma	Always	No	No
Eosinophilia	Marked	Mild/absent	Mild/absent
ANCA	~50%, p-ANCA (anti-MPO)	~90%, c-ANCA (anti-PR3)	~70%, p-ANCA
Granulomas	Eosinophil-rich, no giant cells	Necrotizing with giant cells	Absent
Renal involvement	Less common	Common	Common

Recent evidence update: A 2025 BSR Practice Guideline (PMID 40499922) covers updated management of ANCA-associated vasculitis including EGPA. A 2025 systematic review (PMID 40766318) confirms the efficacy of anti-IL-5/IL-5R therapies (mepolizumab, benralizumab) for EGPA.

Sources: Harrison's Principles of Internal Medicine 22E (2025), pp. 2943-2944; Andrews' Diseases of the Skin, pp. 4684-4692; Rheumatology 2-Volume Set (2022 Elsevier), pp. 6513-6527

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