MPO and anti-neutrophil cytoplasmic antibody-associated vasculitis: Although the patient was ANCA-positive with cutaneous features often seen in ANCA vasculitis, the absence of elevated MPO and PR3 antibodies, lack of glomerular crescent formation, and presence of tubulointerstitial injury suggest that the renal manifestations may have resulted from drug-induced acute interstitial nephritis rather than classic ANCA-associated vasculitis.