title: BK polyoma virus nephropathy in the native kidney.
abstract: BACKGROUND
  While BK polyoma virus nephropathy (PVN) is a well-recognized cause of renal allograft dysfunction, PVN of native kidneys is likely under-recognized.
  
  
  METHODS
  We present the pathologic features, risk factors and outcomes of eight cases of PVN in native kidneys.
  
  
  RESULTS
  The cohort included eight males aged 16-73 years (mean 47.4) with an immunocompromised state (mean duration 3.15 years) attributable to: hematologic malignancies (n = 6), for which three had undergone bone marrow transplant; lung transplant (n = 1) and combined tuberculosis and diabetes (n = 1). Seven patients were receiving specific immunosuppressive therapies. Patients were biopsied for acute kidney injury (AKI) with rise in mean creatinine levels from baseline 1.6 to 2.8 mg/dL. Pathology showed BK PVN with characteristic intranuclear inclusions staining positive for SV40 T antigen and negative for JC virus (JCV), with positive serum and/or urine PCR for BK virus. One patient had focal medullary JCV co-infection. Two patients also had renal infiltration by chronic lymphocytic leukemia (CLL). Six patients received specific therapy directed to PVN (cidofovir or leflunomide). Follow-up ranged from 2 to 20 (mean 10) months. Despite marked decrease in serum BK viral copy numbers, creatinine continued to rise in six cases (mean 3.7 mg/dL in four, requiring dialysis in two) and three patients died of malignancy, opportunistic infection or renal failure. Advanced histologic stage of PVN, ineffective antiviral therapy, co-morbidities and persistent immunocompromised state likely contributed to the poor outcomes.
  
  
  CONCLUSIONS
  A high level of suspicion in immunocompromised patients is needed to diagnose PVN in an early stage that may respond more favorably to antiviral therapy.
authors.affiliation: Department of Pathology, ColumbiaUniversity Medical Center, New York, NY, USA. drshreegopal@gmail.com
authors.forename: Shree G
authors.initials: SG
authors.lastname: Sharma
authors.forename: Volker
authors.initials: V
authors.lastname: Nickeleit
authors.forename: Leal C
authors.initials: LC
authors.lastname: Herlitz
authors.forename: Anne K
authors.initials: AK
authors.lastname: de Gonzalez
authors.forename: Michael B
authors.initials: MB
authors.lastname: Stokes
authors.forename: Harsharan K
authors.initials: HK
authors.lastname: Singh
authors.forename: Glen S
authors.initials: GS
authors.lastname: Markowitz
authors.forename: Vivette D
authors.initials: VD
authors.lastname: D'Agati
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001739:BK Virus / Q000472:pathogenicity*; D005500:Follow-Up Studies; D006801:Humans; D016867:Immunocompromised Host; D007674:Kidney Diseases / Q000175:diagnosis / Q000821:virology*; D016030:Kidney Transplantation; D008297:Male; D008875:Middle Aged; D027601:Polyomavirus Infections / Q000175:diagnosis / Q000821:virology*; D011379:Prognosis; D012189:Retrospective Studies; D014184:Transplantation, Homologous; D014412:Tumor Virus Infections / Q000175:diagnosis / Q000821:virology*; D055815:Young Adult