MPO and microscopic polyangiitis: She had microscopic hematuria with 4-10 red blood cells/high power field (HPF), and no red blood cell casts were noted. Renal biopsy showed "diffuse crescentic glomerulonephritis, MPO-ANCA associated...no immune complexes seen on electron microscopy." The diagnosis of MPA was made based on these findings consistent with the 2022 American College of Rheumatology/European Alliance of Associations for Rheumatology classification criteria for MPA [6].