POS-739 AN INTERESTING CASE OF CHRONIC ALLOGRAFT DYSFUNCTION

Abstract

Among renal transplants, chronic allograft dysfunction is defined as a condition in which irreversible damage to the kidney allograft occurs over a period of months. Here, we report a case of late presentation of graft dysfunction due to BK Virus with negative urine decoy cells & Negative BK Virus DNA PCR. A 18 year old young male underwent renal transplantation following which renal functions recovered to creatinine of 0.8 mg/dl with mother being donor. Patient was compliant & on regular follow up. After 1 year of renal transplantation, patient's creatinine was found to be 2.1 mg/dl with no symptoms and signs. Patient was admitted and was evaluated. Urine showed no proteinuria, blood & urine cultures were negative with normal counts. Ultrasound of transplant kidney showed no issues. Tacrolimus levels were within limits. All reversible factors contributing were ruled out. Viral etiology were sought for. CMV IgM was negative. Urinary decoy cells were not seen. BK virus DNA PCR also turned out to be negative. BK virus was ruled out of differentials. During the course of hospital stay, creatinine worsened to 2.7. At this stage notwithstanding , Renal biopsy of transplant kidney was done. Biopsy showed features of BK Virus nephropathy with viral cytopathic changes of the tubular cells. Among alloantigen independent causes of chronic allograft dysfunction; and among infections, CMV is the most common. Infections do appear in the early post transplant period when the patients are most immunosupressed. BK Virus is a polyoma virus hominis 1 which causes PVAN(polyoma virus associated nephropathy) in humans is seen in ∼5% of kidney transplant recipients and has emerged as an important cause of allograft dysfunction over the last 20 years with 5 year graft failure rate of 55% presenting with asymptomatic increase in serum creatinine.BK virus is diagnosed by Decoy cells in urine seen in over 90% of the infected patients. BK Virus DNA PCR is very sensitive . The gold standard being Renal biopsy of transplant kidney with tubulointerstitial nephritis , inclusions in tubular cells & Immunohistochemistry confirming BK Virus.In our case, interestingly, Decoy cells & DNA PCR was negative with positive Biopsy for BK Virus. In our case, Mycophenolate mofetil was stopped . Patient was treated with leflunomide, following which patients creatinine came down and stabilised at 2.5 mg/dl. BK Virus nephropathy is a great masqurader which may often camouflage itself & misguide the clinician with negative urine decoy cells & PCR. Prompt workup is necessary including renal biopsy if clinically suspicious. This is one such case report where BK Virus nephropathy was diagnosed.