Late-onset cytomegalovirus-associated interstitial nephritis in a kidney transplant.

Cytomegalovirus is the most important viral infection in kidney transplants, but rarely affects the allograft after the sixth month posttransplantation. We present a patient who developed renal failure eighteen months posttransplant; a kidney biopsy showed cytomegalovirus inclusions, acute tubular necrosis and mild interstitial nephritis. After intravenous ganciclovir, renal function transiently improved. Cytomegalovirus pp65 antigen was weekly reported as negative. One month later another biopsy was performed due to renal failure. The findings were consistent with tubular atrophy and severe interstitial nephritis. No cytomegalovirus cellular inclusions were found on histology, including immunohistochemical and polymerase chain reaction studies; pp65 antigen studies were persistently negative. Despite an attempt to recover renal function with steroid therapy, the patient restarted hemodialysis 20 months posttransplantation. This report suggests that cytomegalovirus should be considered as a late cause of kidney failure even in the absence of infection-related symptoms. The irreversible allograft damage can be caused despite the successful eradication of the virus with intravenous ganciclovir.