Abstract:

A 31yearold male presented with deterioration of renal function 11 months after having undergone  allogeneic hematopoietic stem cell transplant (alloHSCT) for acute lymphoblastic leukemia.He had a mild proteinuria,without hematuria,BK viruria greater than 5×108copies,and negative BK viremia.A renal biopsy demonstrated classical findings of BK virus nephropathy of severe tubulointerstitial injury,and many tubular intranuclear inclusions typical of BK polyoma virus,with immunostaining positive for BK virus large Tantigen.The diagnosis was BK virus nephropathy.The immunosuppressive drugs were changed to sirolimus and methylprednisolone.At the end of a 2 months followup,the patients renal function gradually recovered.