Peri-cystic lesions in ANCA-associated fibrosing interstitial lung disease

<bold>Introduction:</bold> Peri-cystic lesions (PCLs), consisting of condensation or ground glass opacities in contact with cystic fibrosing lesions, have been described on CT scans in ANCA-associated fibrosing interstitial lung disease (ANCA-fILD). The aim of the study was to describe the evolution of PCLs and to compare them to the clinical course, to the presence pulmonary fibrosis progression, and to the ANCA titer. <bold>Material and method:</bold> Patients with fibrosing ILD and positive ANCA were included in 6 french hospitals. Peri-cystic lesions were measured on successive scans, and their evolution between 2 scans was compared to clinical evolution, progression of pulmonary fibrosis, Birmingham Vasculitis Activity Score, and variation in the ANCA titers. <bold>Results:</bold> 34 patients were included and 50 pairs of scans - defining the 50 cases - were analyzed. At baseline, PCLs were present in 24 patients. Improvement of PCLs was associated with overall clinical improvement (p=0.02, Fisher exact test), absence of pulmonary fibrosis progression (p<0.001), and improvement of the ANCA titer (p=0.03). Improvement of the PCLs was not associated with improvement of the BVAS score (p=0.17). <bold>Conclusion:</bold> The evolution of PCLs appears to be of interest for the evaluation of the evolution of ANCA-fILD.