Native BK Polyomavirus Nephropathy in an Orthotopic Heart Transplant Patient

BK polyomavirus nephropathy (BKVN) is a common cause of nephropathy in kidney transplant patients and is typically seen within the first year after transplantation. BK polyomavirus nephropathy can occur in the native kidneys of patients with nonrenal solid-organ transplants (NRSOT). However, this is rare, especially outside the early post-transplant period, and BKVN is not usually considered in the differential diagnosis for acute kidney injury in NRSOT patients. We present a case of a 75-year-old man who had undergone orthotopic heart transplant 13 years prior with stable allograft function who developed progressive renal dysfunction in the setting of recent unilateral obstructive nephrolithiasis requiring ureteral stenting. Kidney biopsy demonstrated evidence of polyomavirus nephritis. Serum BK viral load was elevated. Despite reducing immunosuppression and initiating leflunomide, viral clearance was never achieved. The patient experienced progressive failure to thrive before ultimately transitioning to hospice care and dying. The intensity of immunosuppression is a well-known risk factor for viral replication; ureteral stenting has also been associated with BKVN. However, since clinical manifestations of BK viral infections often include a genitourinary (GU) tract pathology, it is important for clinicians to consider BKVN in patients with NRSOT with progressive renal dysfunction, especially in the clinical context of known GU disease.