29th January 2024

Eosinophilic granulomatosis with polyangiitis (Churg-Strauss syndrome)

Background

Epidemiology 

This disease typically affects middle-aged individuals, with equal distribution of disease amongst males and females. 

Aetiology

Unknown, however, the cause is likely multifactorial with genetic, environmental and infective precipitants. 

Pathophysiology 

Unidentified allergens stimulate an adaptive immune response, leading to a B-cell response and IgG4, IgE and ANCA production. This process guides eosinophils to the tissues and stimulates degranulation of activated eosinophils, causing damage and necrosis of tissues and vessels. 

Clinical features

The chief presentation in patients is severe allergic asthma attacks. This is often associated with allergic rhinitis, nasal polyps or sinusitis. These symptoms can present long before the onset of vasculitis, which may involve the skin, lungs, nerves, kidney and other organs. Approximately 30% of patients have pulmonary infiltrates with some developing pulmonary haemorrhage. Kidneys are frequently affected with pauci-immune glomerulonephritis with associated hypertension. Other complications include impaired mental status, mononeuritis multiplex (75%), pericarditis, congestive heart failure, myocardial infarction, gastrointestinal bleed, ischaemia and perforation. Skin nodules and palpable purpura can present in around 50% of cases. 

Diagnosis 

The clinical history and associated asthma, mono/poly-neuropathy and paranasal sinus abnormalities aid diagnosis. Peripheral blood eosinophilia (>1.5×109/L) and raised IgE levels are characteristic of the disease, with 40% having positive anti-MPO pANCA levels. CXR to look for pulmonary infiltrates, as well as other imaging may be required according to the clinical presentation. Diagnosis is confirmed by tissue biopsy (typically of the lung, skin, nerve or kidney) with eosinophilia, necrotising vasculitis and necrotising granuloma.

Treatment 

The disease process is usually responsive to high-dose prednisolone (e.g. 40-60mg/day). This is usually tapered down, and other immunosuppressive drugs such as azathioprine, methotrexate, cyclophosphamide or rituximab may be used in addition. ESR and eosinophil count are often useful markers for monitoring of disease activity. 

References

• Wallace, Z.S. and Miloslavsky, E.M., 2020. Management of ANCA associated vasculitis. BMJ, 368.
• About vasculitis, Vasculitis UK. Available at: https://www.vasculitis.org.uk/about-vasculitis [Accessed 28th January 2022].
• Bessant, R., Borms, J., Ford, C., 2020.Medicine for MRCP. Oxford Specialty Training 
• Vaglio, A., Buzio, C. and Zwerina, J., 2013. Eosinophilic granulomatosis with polyangiitis (Churg–Strauss): state of the art. Allergy, 68(3), pp.261-273.
• Vasculitides, Amboss. Available at: https://www.amboss.com/us/knowledge/Vasculitides/ [Accessed 17th January 2022].
• Vasculitis, American College of Rheumaology. Available at: https://www.rheumatology.org/I-Am-A/Patient-Caregiver/Diseases-Conditions/Vasculitis [Accessed 17th January 2022].