Acute Tubulointerstitial Nephritis with Antineutrophil Cytoplasmic Antibody

We present a case of acute tubulointerstitial nephritis that developed in a 77-year-old woman who had a high titer of myeloperoxidase (MPO)-antineutrophil cytoplasmic antibody (ANCA). The constellation of clinical, laboratory and histopathologic findings suggested idiopathic acute tubulointerstitial nephritis. Of interest, no drugs were found to be responsible. Therefore, MPO-ANCA itself might play a causative role in the development of acute tubulointerstitial nephritis.