Biopsy-proven BK polyomavirus nephropathy in a lung transplant recipient

BK polyomavirus (BKPyV) nephropathy is a well-known cause of graft loss after kidney transplantation. In contrast, BKPyV-associated disease of native kidneys in non-renal solid organ transplant (NRSOT) recipients is rare and insufficiently characterized. Lung transplant (LuTx) recipients frequently develop chronic kidney disease (CKD), often by default attributed to calcineurin inhibitor (CNI) toxicity. We present a case of a 42-year-old woman with cystic fibrosis who underwent bilateral lung transplantation six years ago and subsequently developed biopsy-proven BKPyV nephropathy with progressive kidney failure. This case highlights the importance of early BKPyV testing in NRSOT recipients with otherwise unexplained kidney injury, the role of kidney biopsy in this population and the high risk of progression to kidney failure despite reduction of immunosuppression. Improved awareness, screening recommendations, prognostic biomarkers and better therapeutic options are warranted to treat BKPyV in NRSOT recipients.