Is Chest Imaging Alone Adequate for Diagnosing Interstitial Lung Disease in Microscopic Polyangiitis Based on the...

To investigate the concordance rate between chest imaging and lung biopsy results for interstitial lung disease (ILD) in patients with microscopic polyangiitis (MPA) and to compare their clinical utility for MPA classification.

This study included 24 patients who had both chest imaging and lung biopsy results at diagnosis and who fulfiled the 2022 American College of Rheumatology/European Alliance of Associations for Rheumatology criteria for MPA. Concordance was defined as the concurrent confirmation of ILD on chest imaging and lung biopsy. Positive and negative predictive values were assessed in patients with and without ILD on chest imaging, respectively, and compared with histologically confirmed ILD on lung biopsy.

The median age was 73.5 years, and all patients had myeloperoxidase (MPO)-antineutrophil cytoplasmic antibody. Among the 24 patients, 10 (41.7%) and 5 (20.8%) exhibited radiological and histological findings consistent with ILD, respectively. Among the 10 patients with radiological findings of ILD, only 4 exhibited histological features consistent with ILD on lung biopsy, leading to a concordance rate of 40%. Conversely, among the remaining 14 patients without radiological findings of ILD, 13 showed histological features inconsistent with ILD on lung biopsy, resulting in a concordance rate of 92.9%.

Lung biopsy should be considered in highly selected patients who are MPO-positive without involvement of other organs. The decision to determine the need for lung biopsy should be made by a multidisciplinary team.