A 60-year-old man was admitted to our clinic with dyspnea, hemoptesis, anuria, nephritic syndrome, and a positive myeloperoxidase antineutrophil cytoplasmic antibody titer. He was diagnosed with antineutrophil cytoplasmic antibody-associated vasculitis due to Wegener granulomatosis, microscopic polyangiitis, or drug induction. Unexpectedly, histopathologic examination of the kidney biopsy speci...