Persistently high-level polyomavirus BK replication in the absence of renal function abnormalities in a kidney transplant recipient

Polyomavirus-associated nephropathy is an important cause of allo-graft dysfunction and graft loss after kidney transplantation. Even ifhistological evaluation is the gold standard for graft study and diagno-sis of polyomavirus-associated nephropathy, K-DIGO guidelines sug-gest performing an indication biopsyin selected patient’s clinical con-ditions or laboratory parameters. The practice of protocol biopsyis stillcontroversial. We report the management of a case of presumptivepolyomavirus-associated nephropathy in a 53-year-old kidney trans-plant recipient affected by type 1 hyperoxaluria with persistent highlevels of viruria and sustained levels of polyomavirus BK viremia. Thepresence of a presumptive polyomavirus-associated nephropathy, evenif never confirmed by biopsy, never compromised his clinical conditionand allograft function. As a result of an immunosuppression-sparingpolicy and use of mTOR inhibitor, the polyomavirus BK viremia wassuccessfully controlled with an observation time >5 years. The deci-sion to perform or not a graft biopsy was the main question in themanagement of this case. We opted for a non-invasive approachbecause of the high risk of biopsy with macrohematuria on earlierbiopsy in a dual kidney transplant and patient’s unwillingness for theprocedure. The replication level of polyomavirus BK was significantlyreduced by the decrease of immunosuppression on the basis of a closenucleic acid testing monitoring. The strategy we adopted could be con-sidered in cases when renal biopsy is contraindicated or considered tobe high risk