MPO and Pulmonary hemorrhage: Among the 11 cases in our series, 4 patients (36.4%) were ANCA-positive (1 PR3-ANCA and 3 MPO-ANCA), and only 3 cases (27.3%) exhibited pulmonary hemorrhage, whereas the remaining 8 cases (including the present case) had no lung hemorrhage, as summarized in Table 2.