Churg-Strauss Syndrome (CSS) is a systemic vasculitis characterised by the presence of asthma and hypereosinophilia. It is generally considered a disease of adults. The incidence of CSS is estimated at 2.4 per million per year.
The classic histopathological findings are vasculitis, necrotising extra-vascular granulomas and eosinophilic infiltration, even if these three features rarely coexist in the same biopsy specimen. Clinical extra-pulmonary manifestations include weight loss, myalgia, arthralgia, skin lesions (nodules, purpura, or urticaria), neurological, renal, gastrointestinal and cardiac involvement.
The diagnosis of CSS by the American College of Rheumatology (ACR), requires 4 or more of the following clinical criteria: 1) the presence of asthma; 2) peripheral eosinophilia (>10%); 3) mononeuropathy or polyneuropathy; 4) temporary or migratory pulmonary infiltration; 5) para-nasal sinus abnormality; and 6) a biopsy specimen containing a blood vessel with extra-vascular eosinophils.
The presence of 4 of the 6 criteria is thought to have a diagnostic sensitivity of 85% and specificity of 99.7%.[1-2]
The clinical evolution of CSS is divided into three stages: the prodromal phase, that involves allergic rhinitis and asthma and can be protracted for many years; the second phase includes peripheral eosinophilia and eosinophilic tissue infiltration; in the final phase, the hallmark is a systemic vasculitis, which can be fatal.
The predominant causes of death include heart, renal and cerebral failure, and gastrointestinal perforation or haemorrhage. Cardiovascular disease occurs in approximately half of the patients with CSS.
CSS is considered to be one of the antineutrophil cytoplasmic antibody (ANCA)-associated systemic vasculities (AASVs). The pathogenesis is not well understood: neutrophils, when activated by ANCA, release oxygen radicals, lytic enzymes and inflammatory cytokines and adhere to endothelial cells and this causes apoptosis and necrosis.
Therapy consists of corticosteroids only or together with cyclophosphamide, or plasma exchanges. The long-term prognosis of CSS is good, although most patients need low doses of oral or inhaled corticosteroids for persistent asthma.[3]
In chest radiograph, the Churg-Strauss syndrome usually appears as bilateral nonsegmental consolidation or reticulonodular opacities. The most common CT findings include sub-pleural ground-glass opacity or consolidation with a lobular distribution, bronchial wall thickening, and interlobular septal thickening.