PRTN3 and microscopic polyangiitis: According to the 2022 American College of Rheumatology/European Alliance of Associations for Rheumatology (ACR/EULAR) classification criteria, the patient scored 9 points (MPO-ANCA positivity and interstitial lung disease, without PR3-ANCA, sinonasal disease, or eosinophilia), supporting the diagnosis of MPA [10]. Based on these findings, microscopic polyangiitis (MPA) was diagnosed.