Difference in chest HRCT findings in relation to ANCA subtypes in ANCA-associated vasculitis

Objective: To classify high-resolution computed tomography (HRCT) images in relation to ANCA subtype in patients with ANCA-associated vasculitis (AAV) enrolled in an observational cohort study. Methods: 196 AAV patients who underwent HRCT at the time of AAV diagnosis from 2011 through 2013 were evaluated. Interstitial pneumonia (IP) pattern was classified as definite, possible, and inconsistent with usual interstitial pneumonia (UIP), according to ATS/ERS/JRS/ALAT guidelines for IPF. In addition, we evaluated the association of HRCT findings and ANCA subtypes. Results: Abnormal chest HRCT findings were noted in 172 of 196 patients. The main HRCT findings were ground glass opacity (n=92; 47%), reticulation (n=79; 63%), traction bronchiectasis (n=67; 34%), honeycombing (n=49; 25%), nodules (n=29; 15%), consolidation (n=27; 14%), bronchiectasis (n=22; 11%), cysts (n=10; 5%), and cavities (n=4; 2%). The prevalences of MPO-ANCA–positive/PR3-ANCA positive/double-positive/double-negative AAV were 161/10/8/17 (82%/5%/4%/9%). Honeycombing (n=46/161; 29%) and reticulation (n=70/161; 43%) were frequent in MPO-ANCA–positive, while nodules (n=4/10; 40%) and cavities (n=3/10; 30%) were frequent in PR3-ANCA–positive patients. Among 89 patients with IP, the prevalences of MPO-ANCA–positive/PR3-ANCA–positive/double-positive/double-negative AAV were 76/1/4/8 (85%/1%/4%/9%). The definite UIP pattern was more frequent in MPO-ANCA–positive than in those with other ANCA subtypes (34% vs 0%; p=0.023). Conclusion: Chest HRCT findings showed that IP with a definite UIP pattern was more frequent in MPO-ANCA–positive patients and that nodules and cavities were more frequent in PR3-ANCA–positive patients.