Eosinophilic granulomatosis with polyangiitis

Last revised by Joshua Kogan on 21 May 2024

Eosinophilic granulomatosis with polyangiitis (EGPA), previously known as Churg-Strauss syndrome is characterized by asthma, eosinophilia and small vessel necrotizing vasculitis and involves the lungs and other organs.

The incidence typically peaks in middle age, 30-50 years of age with pediatric cases being rare 2,16,24. The annual incidence rate of around 0.24-1.78 per 100,000 2,16. There is no gender predilection 24.

Clinically, patients with EGPA pass through three phases. Although these do provide a general overview of progression, the phases do overlap 24:

  • allergic prodrome

    • marked by allergic symptoms typically asthma and sinusitis

    • may last years

  • eosinophilic phase

    • eosinophilia

    • end-organ involvement

  • vasculitic phase

    • small-vessel vasculitis with end organ damage

Almost all patients have symptomatic asthma and chronic sinusitis. Extrapulmonary signs and symptoms will vary depending on end-organ involvement and the phase of the disease and include diarrhea, skin purpura, arthralgias, renal impariment and neurological symptoms.

The 1990 American College of Rheumatology criteria requires a positive biopsy for vasculitis and at least four of the six criteria listed below (sensitivity 85% and specificity 99.7%) 16

  • asthma: present in almost all patients 2

  • blood eosinophilia (>10% of the total white blood cell count): present in almost all patients 2,13

  • mono/polyneuropathy

  • transient pulmonary infiltrates

  • paranasal sinus abnormalities: pain or radiographic abnormality

  • presence of extravascular eosinophils on a biopsy specimen

Can be histologically identical to classic polyarteritis nodosa or microscopic polyangiitis. Around 25% of patients will have renal disease, classically necrotizing crescentic glomerulonephritis 12.

Biopsy of parenchymal opacities may show a mixture of necrotizing granulomas, eosinophilic pneumonia, and granulomatous vasculitis 16

Anti-neutrophil cytoplasmic antibodies (ANCA) is detected in approximarly half of patients, most often against myeloperoxidase (MPO) (pANCA) 24.

The presence of ANCA has an impact on clinical phenotype, with skin rash, neurological involvement and glomerulonephritis more common in ANCA positive patients, whereas pulmonary, cardiac and gastrointestinal involvement is more common in ANCA negative patients 24.

Below are the respiratory and cardiac imaging features. Neurological manifestations of EGPA are discussed separately.

Chest radiographs are nonspecific but may show:

Imaging features include:

  • peripheral or random parenchymal opacification (consolidation or ground glass)

    • tends to be the most frequent feature 1; can be transient

    • often bilateral and can sometimes be symmetrical 14

    • parenchymal opacification is predominantly peripheral or random in distribution 1

  • less common features include

  • regular and smooth interlobular septal thickening: may reflect the presence of edema secondary to cardiac involvement or eosinophilic septal infiltration 14

  • cavitation: rare and if present other co-existing pathology should be considered, e.g. granulomatosis with polyangiitis, infection 6

  • mediastinal lymphadenopathy: seen in less than 25% of cases 16

  • paranasal sinus disease 19-22

Cardiac involvement clinically manifests in about 66% of patients and can be found in up to 92% of autopsies 16. They include: 

Corticosteroids (most commonly prednisone) are the mainstay of treatment. Patients with cardiac, renal, gastrointestinal, or CNS involvement, require additional immunosuppression (e.g. cyclosporine, azathioprine).

The condition generally has a low mortality rate compared with other systemic vasculitides 11. Cardiac involvement may, however, be a significant contributor to disease-related death and may occur in up to 60% of cases 8,13.

Eosinophilic granulomatosis with polyangiitis was first described in 1951 by Jacob Churg (1910-2005), an American pathologist, subspecialising in renal and vascular diseases, and his long-term collaborator and friend Lotte Strauss (1913-1985) an American pediatric pathologist, who were both based at Mount Sinai Hospital in New York City 4,18.

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