[Pulmonary imaging in ANCA-associated vasculitides]

Imaging of ANCA-associated vasculitides principally shows nonsystematized alveolar opacities, predominantly central, that suggest alveolar hemorrhage, as well as uni- or multifocal alveolar opacities of variable interpretation, and nodules, including cavitary nodules. Other signs, observed more rarely on imaging, are interstitial lung diseases, tracheobronchial involvement, and pulmonary hypertension. The principal pulmonary signs of Wegener's granulomatosis are nodules and masses, sometimes cavitary, and areas of airspace consolidation that may or may not suggest diffuse alveolar hemorrhage. Except when the latter is present, the lesions correspond to necrotizing granulomatosis or organized pneumonia. The most frequent pulmonary signs of Churg-Strauss syndrome on computed tomography are ground glass areas or parenchymal consolidation in dispersed bands or with a predominantly subpleural distribution that expresses eosinophilic interstitial and alveolar infiltration. Alveolar hemorrhage is the most common expression of microscopic polyangiitis.