Prevalence and Responsiveness to Treatment of Lung Abnormalities on Chest Computed Tomography in Patients With Microscopic Polyangiitis: A Multicenter, Longitudinal, Retrospective Study of One Hundred Fifty Consecutive Hospital‐Based Japanese Patients

Abstract

Objective. To determine the prevalence of lung abnormalities on chest computed tomography (CT) in patients with microscopic polyangiitis (MPA), to assess the responsiveness of such abnormalities to initial treatment, and to assess associations between these abnormalities and patient and disease characteristics and mortality.Methods. We retrospectively identified 167 consecutive hospital-based patients with MPA in 3 hospitals in Japan. We longitudinally collected clinical information for 150 of these patients, for whom CT images obtained before treatment were available. We then determined the presence of 22 imaging components of lung abnormalities in these patients.Results. The vast majority of patients (97%) had at least 1 lung abnormality on chest CT images, including interstitial lung lesions (66%), airway lesions (66%), pleural lesions (53%), and emphysematous lesions (37%). In multivariate analyses, ground-glass opacity was associated with the Birmingham Vasculitis Activity Score, whereas 3 of 4 airway lesions were associated with myeloperoxidase-antineutrophil cytoplasmic antibodies. Latent class analysis identified a distinct group of patients with airwaypredominant lung lesions. Airway lesions such as bronchiolitis and bronchovascular bundle thickening were among the components that showed improvement within 3 months of the initial treatment. An idiopathic pulmonary fibrosis pattern was the only chest CT variable that was independently associated with shorter survival.Conclusion. Abnormalities in a wide range of anatomic areas, including the whole airway, can be identified in the lungs of patients with MPA before treatment. The prevalence, clustering patterns, and responsiveness to treatment of individual lung abnormalities provide groundwork for informing future studies to understand the pathophysiology of MPA.Microscopic polyangiitis (MPA) is a necrotizing systemic vasculitis that affects small to medium-sized vessels. In MPA, immune deposits on the vessel wall are usually absent, and serum antineutrophil cytoplasmic antibodies (ANCAs) are frequently present. MPA shares these

The Respiratory System in Autoimmune Vascular Diseases

“…In addition, some airway abnormalities were seen in 66% of patients, described as bronchiolitis (55%), bronchial wall thickening (44%), and bronchiectasis (32%). Pleural lesions were also reported in 53% of cases and described as pleural thickening in 34% and effusion in 26% of cases [52]. Another series of 40 patients reported that pulmonary complaints and infiltrates were present in 80 and 92% of patients, respectively [53].…”

Interstital lung disease in ANCA vasculitis

“…Interstitial lung lesions are a frequent finding in radiologic studies of ANCA-V patients [64]. In a cohort of 150 MPA individuals, CT images obtained before treatment showed that 97% presented at least one lung abnormality, including interstitial lung changes in 66% [64].…”

“…Similarly, in another study that included 62 MPO-ANCA cases (51 with MPA), 82% had an abnormal CT scan, 94% of which displayed findings suggestive of interstitial involvement [65]. Most of these interstitial lesions are non-specific and only a small number of patients will actually show a CT pattern corresponding to some specific idiopathic interstitial pneumonia, such as usual interstitial pneumonia (UIP) or non-specific interstitial pneumonia (NSIP) [64,66]. …”

“…Airway abnormalities are reported in the form of bronchiolitis (55%), bronchial wall thickening (44%) or bronchiectasis (32–38%) [17,64]. With respect to distribution, interstitial involvement was reported to be symmetrical in 50–100% of patients, affecting predominantly the lung periphery and lower areas [15,18,48,65].…”

“…1) [15,17,18,20,51]. Combined pulmonary fibrosis with emphysema has been recently reported in MPA patients [35,51,64,68]. Importantly, 4–40% of studied cases will not fit any specific CT-pattern [15,17,18,20,51].…”