Differences in chest HRCT findings in relation to ANCA subtypes in ANCA-associated vasculitis.

BACKGROUND: Differences in chest HRCT findings between myeloperoxidase (MPO)- antineutrophil cytoplasmic antibody (ANCA) and proteinase 3 (PR3)-ANCA in Japanese patients with ANCA-associated vasculitis (AAV) remain unclear. METHODS: We reviewed chest HRCT findings at diagnosis in 195 patients with AAV enrolled in the Remission Induction Therapy in Japanese Patients with ANCA-associated Vasculitis and Rapidly Progressive Glomerulonephritis (RemIT-JAV-RPGN) observational cohort study (2011-2013). Findings were classified by ANCA subtype and compared. RESULTS: Abnormal chest HRCT findings were observed in 172 of 195 patients. Main findings included ground-glass opacity (n = 92, 47%), reticulation (n = 79, 41%), traction bronchiectasis (n = 67, 34%), and honeycombing (n = 4 9, 25%). Honeycombing (n = 46, 29%) and reticulation (n = 70, 43%) predominated in patients with positive MPO-ANCA, whereas nodules (n = 4, 44%) and cavities (n = 3, 33%) were more frequent in those with positive PR3-ANCA. Interstitial pneumonia (IP) was diagnosed in 89 patients, with HRCT patterns of definite usual interstitial pneumonia (UIP) in 31 (35%), possible UIP in 22 (25%), and inconsistent with UIP in 36 (40%). IP was more frequent in patients with positive MPO-ANCA than in those with positive PR3-ANCA (47% vs 11%, respectively; p = 0.003). Definite UIP was more common in MPO-ANCA positivity than in other subtypes (41% vs 0%, respectively; p = 0.023). CONCLUSIONS: In Japanese patients with AAV, IP with a definite UIP pattern was more frequent in patients with MPO-ANCA positivity while nodules and cavities were more frequent in patients with positive PR3-ANCA.