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Eosinophilic Granulomatosis with Polyangiitis

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Overview

Formerly known as Churg-Strauss syndrome, eosinophilic granulomatosis with polyangiitis (EPGA) is an ANCA-associated small- to medium-sized vessel vasculitis of unknown aetiology associated with asthma.

There is a classic pathological triad of tissue eosinophilia, granulomatous inflammation, and eosinophilia.

Epidemiology

  • Mean age of onset is 38-54 years and the median is 40
  • There is no gender difference in incidence
  • EGPA is a rare disease

Presentation

The presentation of EGPA depends on the system involved.

In any patient with asthma and/or nasal polyps, suspect EGPA if there are any new or worsening general symptoms.

Consider EGPA in a patient with refractory asthma with high eosinophilia (>10% of the white cell count)

  • Respiratory
    • Asthma – dyspnoea, wheezing (asthma is generally difficult to control)
    • Sinusitis, nasal discharge, nasal stuffiness
  • Skin
    • Palpable purpura and petechiae
  • General symptoms:
  • Neurological symptoms:
    • Mononeuritis multiplex

Differential Diagnoses

Granulomatosis with polyangiitis (GPA) 

  • GPA does not have asthma
  • GPA does not have eosinophilia
  • GPA is associated with cANCA, EGPA is associated with pANCA
  • Peripheral neuropathy more common in EGPA

Severe asthma

  • Features of vasculitis such as palpable purpura and petechiae are not present

Investigations

  • Full blood count:
    • Eosinophils are raised
  • Anti-neutrophil cytoplasmic antibodies (ANCA):
    • pANCA is associated with EGPA
  • Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP):
    • Usually raised during active vasculitis
  • Urea and electrolytes (U&Es):
    • To screen for glomerulonephritis
  • Urinalysis:
    • To screen for glomerulonephritis
  • Pulmonary function tests:
    • To assess for asthma, which is common in EGPA
  • Chest x-ray or CT scan:
    • This may show interstitial infiltrates or nodules

Management

Management generally involves inducing remission with the use of corticosteroids with or without cyclophosphamide, and methotrexate or azathioprine in some scenarios.

Patient Advice

  • As EPGA can cause a plethora of symptoms, patients should be educated on when to seek medical help if they develop new symptoms e.g. shortness of breath, haemoptysis, joint pain, rashes, or new paraesthesia or weakness.

Complications

  • Complications depend on the specific organ being involved
  • Cardiac and neurological complications are serious and are more likely in patients with a delayed diagnosis

Prognosis

  • Without treatment, the 5-year survival rate is around 25%
  • Features associated with an increased risk of mortality are:
    • Proteinuria
    • Renal insufficiency
    • Cardiomyopathy
    • Gastrointestinal involvement
    • CNS involvement

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