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Respiratory system involvement in systemic vasculitides.

The respiratory system may be involved in all systemic vasculitides (SV), although with a variable frequency. Lung disease is a very common and important feature of the antineutrophil cytoplasmic antibodies (ANCA)-associated SV (AASV), such as Wegener's granulomatosis (WG), Churg-Strauss syndrome (CSS), and microscopic polyangiitis (MPA). In WG, almost all patients have either upper airway or lower respiratory tract disease. Solitary or multiple nodules and masses are the most common findings on chest radiograph. Asthma is a cardinal symptom of CSS, often preceded by allergic rhinitis, frequently complicated by nasal polyposis and sinusitis. Pulmonary transient and patchy alveolar infiltrates are the most common radiographic findings. In MPA, diffuse alveolar hemorrhage (DAH) due to alveolar capillaritis is the most frequent manifestation of the respiratory involvement, clinically expressing with hemoptysis, respiratory distress and anemia. However, DAH may be subclinical and has to be suspected when chest radiograph demonstrates new unexplained bilateral alveolar infiltrates, in the face of falling hemoglobin levels. In giant cell arteritis, the most frequent respiratory symptom is cough, usually non-productive, persistent, and responsive to corticosteroids. In Takayasu arteritis, pulmonary involvement is frequently subclinical and detectable by non-invasive techniques. Pulmonary involvement is rare in polyarteritis nodosa, Kawasaki disease, Henoch-Schönlein purpura and cryoglobulinemic vasculitis. In conclusion, the involvement of the respiratory system is a very common and important feature of AASV, whereas is less frequent in other SV. It comprises a wide spectrum of clinical features and radiological findings, and may have a prognostic significance. The assessment of the respiratory system should be included in the work-up of all patients with SV, especially of those with AASV.