Eosinophilic granulomatosis with polyangiitis

Eosinophilic granulomatosis with polyangiitis (EGPA), previously known as the Churg-Strauss syndrome (CSS), refers to a small to medium vessel necrotizing pulmonary vasculitis. It is also classified under the spectrum of eosinophilic lung disease and as a type of pulmonary angiitis and granulomatosis.

Epidemiology

The incidence typically peaks around the 3 to 4 decade with an annual incidence rate of around 0.24-1.78 per 100,000 .

Clinical presentation

Almost all patients have asthma and eosinophilia. Patients also have extrapulmonary signs and symptoms such as sinusitis, diarrhea, skin purpura, and/or arthralgias.

Diagnostic criteria

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%) :

  • asthma: present in almost all patients
  • blood eosinophilia ( >10% of the total white blood cell count): present in almost all patients
  • mono/polyneuropathy
  • transient pulmonary infiltrates
  • paranasal sinus abnormalities: pain or radiographic abnormality
  • presence of extravascular eosinophils on a biopsy specimen

Pathology

Can be histologically identical to classic polyarteritis nodosa or microscopic polyangiitis. Around 25% of patients will have renal disease .

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

Markers

Radiographic features

Plain radiograph

Chest radiographs are nonspecific but may show:

  • peripheral consolidation, which may be transient/migratory
  • small pleural effusions - up to 50% of cases
CT

Imaging features include:

  • peripheral or random parenchymal opacification (consolidation or ground glass)
    • this tends to be the most frequent feature ; can be transient
    • often bilateral and can sometimes be symmetrical
    • parenchymal opacification is predominantly peripheral or random in distribution
  • less common features include
  • regular and smooth interlobular septal thickening: may reflect the presence of edema secondary to cardiac involvement or eosinophilic septal infiltration
  • cavitation: rare and if present other co-existing pathology should be considered, e.g. granulomatosis with polyangiitis, infection
  • mediastinal lymphadenopathy is seen in less than 25% of cases
MRI
Cardiac MRI

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

Treatment and prognosis

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 . Cardiac involvement may, however, be a significant contributor to disease-related death and may occur in up to 60% of cases .

History and etymology

It was first described in 1951 by Jacob Churg and Lotte Strauss, American physicians based in New York .

Differential diagnosis

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