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Abstract: FR-PO046

Native BK Nephropathy: A Case Series

Session Information

Category: Nephrology Education

  • 1302 Fellows and Residents Case Reports


  • Shah, Ankur, University of Pennsylvania, Philadelphia, Pennsylvania, United States
  • Palmer, Matthew, University of Pennsylvania, Philadelphia, Pennsylvania, United States
  • Hogan, Jonathan J., University of Pennsylvania, Philadelphia, Pennsylvania, United States
  • Sawinski, Deirdre L., University of Pennsylvania, Philadelphia, Pennsylvania, United States

BK Polyoma Virus is highly seroprevalent but rarely pathologic in humans. Genitourinary BK disease is most commonly seen after kidney transplantation. Here we present two cases of native kidney BK nephropathy.


The first patient was a 70 yo man with ischemic cardiomyopathy s/p OHT in 2011 and was on tacrolimus, mycophenolate mofetil, and prednisone maintenance immunosuppression. His pre-transplant SCr was 1.5-1.7 mg/dL which remained stable after OHT. In 2013 he experienced a rapid rise in SCr over 5 months to 3.8 mg/dL. His urinalysis was negative for blood and albumin, microscopy showed no cells, and UProt:Cr ratio was 200 mg/g. A kidney biopsy showed tubular epithelial cells with focal glassy nuclear inclusions, and positive nuclear staining for SV40 and Pab597. Serum BK PCR was positive (296075 copies/ml). MMF was stopped. His serum BK viral load decreased and SCr stabilized at 3.5 for approximately 3 years before beginning to rise again and his progressing to ESRD.

The second patient was a 34 yo man who was treated for non-Hodgkin`s lymphoma at age 18 with chemotherapy (CHOP regimen). He was hospitalized for weakness, diarrhea and volume depletion and found to have AKI (Cr 4.0 mg/dL, baseline 1.2 mg/dL) and transaminitis (AST 134, ALT 61 IU/L) Urinalysis showed 500+ mg/dl protein and small blood with 1-2 rbc/hpf on microscopy and UProt:Cr was 13 g/g. A kidney biopsy revealed tubular epithelial cells with widespread degenerative and regenerative epithelial changes, frequent epithelial mitoses and intranuclear inclusions. IHC staining for polyoma virus showed positive nuclear staining in tubular epithelial cells. He was subsequently diagnosed with hemophagocytic syndrome and died of multi-organ system failure.


BK Virus infection has long been described as a cause of renal disease after renal transplantation but has been described in 41 cases to date in non-kidney transplant patients. These patients included HIV, bone marrow transplant, heart transplant, and other solid organ transplant recipients. BK nephropathy in the native kidney should be considered as a cause of renal injury in immunocompromised patients.