Pulmonary involvement in antineutrophil cytoplasmic antibodies (ANCA)-associated vasculitis: The influence of ANCA subtype

Objective. To describe pulmonary involvement at time of diagnos is in a ntineutrophil cytoplasm ic antibodies (ANCA)-associated vasculitis (AAV), as defined by computed tomography (CT). Methods. Pati ents w ith thoracic CT perfor med on or after the onset of AAV (n = 140; 7 5 women; granulomatosis with polyangiitis, n = 79; microscopic polyangiitis MPA, n = 61) followed at a tertiary referral center vasculitis clinic were studied. Radiological patterns of pulmonary involvement were evaluated from the CT studies using a predefined protocol, and compared to proteinase 3 (PR3)-ANCA and myeloperoxidase (MPO)-ANCA specificity. Results. Of the patients, 77% had an abnormal thoracic CT study. The most common abnormality was nodular disease (24%), of which the majority were peribronchial nodules, followed by bronchiectasis and pleural effusion (19%, each), pulmonary hemorrhage and lymph node enlargement (14%, each), emphysema (13%), and cavitating lesions (11%). Central airways disease and a n odular pattern of pulmonary involvement were more common in PR3-ANCA-positive patients (p < 0.05). Usual interstitial pneumonitis (UIP) and bronchiectasis were more prevalent in MPO-ANCA-positive patients (p < 0.05). Alveolar hemorrhage, pleural effusion, lymph node enlargement, and pulmonary venous congestion were more frequent in MPO-ANCA-positive patients. Conclusion. Pulmonary involvement is frequent and among 140 patients with AAV who underwent a thoracic CT study, almost 80% have pulmonary abnormalities on thoracic CT. Central airway disease oc curs exclusively among patients with PR3-ANCA while UIP were mainl y seen in those wit h MPO-ANCA. These findings may have important implications for the investigation, ma nagement, and pathogenesis of AAV.