Synonyms: allergic granulomatosis angiitis, granulomatous small-vessel vasculitis

A rare diffuse vasculitic disease affecting coronary, pulmonary, cerebral, abdominal visceral and skin circulations. The vasculitis affects small and medium sized arteries and veins and is associated with asthma. The aetiology is unknown.¹

Epidemiology

• Incidence is approximately 2.5 cases per 100,000 adults per year.
• Males are affected slightly more frequently than females.
• The age at onset varies from 15-70 years.

Presentation

The physical findings are specific to organ system involvement. There are three phases:

• Allergic rhinitis and asthma.
• Eosinophilic infiltrative disease, such as eosinophilic pneumonia or gastroenteritis.
• Systemic medium- and small-vessel vasculitis with granulomatous inflammation.

The vasculitic phase usually develops within 3 years of the onset of asthma, although it may be delayed for several decades. The most prominent symptoms and signs are:

• Pulmonary: asthma, pneumonitis and haemoptysis.
• Upper respiratory tract: allergic rhinitis, paranasal sinusitis, nasal polyposis.
• Cardiac: heart failure, myocarditis, and myocardial infarction.²
• Skin: purpura, skin nodules, leucocytoclastic angiitis with palpable purpura, livedo reticularis, urticaria, necrotic bullae and digital ischaemia.
• Renal: glomerulonephritis, hypertension and advanced renal failure.
• Peripheral neuropathy: mononeuritis multiplex (most frequent form, occurring in as many as 77% of patients). Less frequent symptoms include stroke and eye involvement.
• Gastrointestinal: vasculitis and bleeding, bowel ischaemia and perforation, appendicitis and pancreatitis.
• Malaise, fatigue, weight loss, fever, myalgia and arthralgia.
• Myositis following unaccustomed exercise has been reported.³

Differential diagnosis

• Other causes of systemic vasculitis:⁴
  • Primary vasculitis, e.g. polyarteritis nodosa, Wegener's granulomatosis.
  • Secondary vasculitis: a complication of a connective tissue disorder (e.g. rheumatoid arthritis), infection, medication, or malignancy.
• Wegener's granulomatosis and microscopic polyangiitis are also vasculitic syndromes involving small and medium-sized vessels that are associated with antibodies to neutrophil cytoplasmic antigens.

Investigations¹

• Antineutrophil cytoplasmic antibodies (ANCA): 70% of patients are perinuclear staining (p-ANCA) positive (antimyeloperoxidase antibodies).
• Other likely findings include eosinophilia and anaemia on the full blood count; elevated ESR and CRP; elevated serum creatinine; increased serum IgE levels, hypergammaglobulinaemia; proteinuria, microscopic haematuria, and red blood cell casts in the urine.
• Chest X-ray: pulmonary opacities, transient pulmonary infiltrates, pleural effusions.
• Pulmonary CT scan: peripheral areas of parenchymal consolidation with ground-glass attenuation similar to chronic eosinophilic pneumonia.
• Biopsy: the characteristic changes, found especially in the lung, include small necrotising granulomas, as well as necrotising vasculitis involving small arteries and venules.
• Other investigations are indicated for the complications of the disease and specific organ system involvement.

Management

• High-dose steroids are usually adequate for treatment.
• Cyclophosphamide is administered in patients with severe or life-threatening complications. Azathioprine is also used.
• Other treatments include intravenous immune globulin, interferon-alpha, and plasma exchange.

Complications

• Complications of vasculitis depend on the specific organ system involvement.
• The principal causes of morbidity and mortality are myocarditis and myocardial infarction secondary to coronary arteritis.

Prognosis

• Although the overall prognosis is good, and treatment with prednisone alone or in combination with immunosuppressive drugs is usually successful, severe asthma typically persists.⁵
• Diffuse organ involvement of Churg-Strauss syndrome, especially cardiovascular and rare involvement of the CNS and renal system, suggests a poorer prognosis and can be fatal.⁵
• Without treatment, the 5-year survival rate is about 25%.
• With treatment, the 1-year survival rate is 90% and the 5-year survival rate is 62%.
• Although treatment regimes are often successful, severe asthma usually persists.