A very early and acute renal impairment due to polyomavirus allograft nephropathy.

Polyomavirus-associated nephropathy (PVAN) has become an important cause of graft loss in the last few years. The typical course of PVAN is characterized by an asymptomatic period of viruria followed, within weeks, by the development of viremia in the context of stable renal function. The persistence of viral replication characterized by high viremia, leads to parenchymal injuries and causes the development, within months, of PVAN that could lead to deterioration in graft function and graft loss. We reported, in a patient who received a renal transplant, an unusual presentation of PVAN characterized by the development of acute renal failurte earlier than would be expected after transplantation, where the histological presentation alone could be confused with an acute rejection. We underline the importance of the association of histological findings with the viral load in urine and blood and with ancillary techniques such as immunohistochemistry and polymerase chain reaction (PCR) in situ for virus detection. We also want to emphasize that decoy cells and PCR for BK virus DNA research could be considered among the diagnostic tools for possible acute renal failure in kidney transplant.