title: Histological patterns of polyomavirus nephropathy: correlation with graft outcome and viral load.
abstract: Polyomavirus-associated nephropathy (PVAN) is a significant cause of allograft loss. The diagnosis requires allograft biopsy, but the impact of the histological features on diagnosis and outcome has not been described. We studied the distribution and extent of PVAN in 90 patients. Viral cytopathic changes, tubular atrophy/fibrosis and inflammation were semi-quantitatively scored and classified into histological patterns. The histological findings were correlated with viruria, viremia and graft survival. PVAN lesions were random, (multi-)focal and affected both cortex and medulla. Areas with PVAN coexisted with areas of unaffected parenchyma. In 36.5% (15/41) of biopsies with multiple tissue cores, discordant findings with PVAN-positive and -negative cores were observed. However, all patients with PVAN had decoy cells in urine as well as significant viruria and viremia (mean of 2.5 x 10(8) and 2.32 x 10(7) viral copies, respectively). Biopsies showing lesser degrees of renal scarring at the time of diagnosis were associated with, more likely, resolution of the infection, in response to decrease of immunosuppression (p = 0.001). More advanced tubulointerstitial atrophy, active inflammation and higher creatinine level at diagnosis correlated with worse graft outcome (p = 0.0002, 0.0001 and 0.0006). Due to the focal nature of PVAN, correlation of biopsy results with viruria and viremia are required for diagnosis.
authors.affiliation: Department of Pathology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
authors.forename: Cinthia B
authors.initials: CB
authors.lastname: Drachenberg
authors.forename: John C
authors.initials: JC
authors.lastname: Papadimitriou
authors.forename: Hans H
authors.initials: HH
authors.lastname: Hirsch
authors.forename: Ravinder
authors.initials: R
authors.lastname: Wali
authors.forename: Clinton
authors.initials: C
authors.lastname: Crowder
authors.forename: Joseph
authors.initials: J
authors.lastname: Nogueira
authors.forename: Charles B
authors.initials: CB
authors.lastname: Cangro
authors.forename: Susan
authors.initials: S
authors.lastname: Mendley
authors.forename: Ayesa
authors.initials: A
authors.lastname: Mian
authors.forename: Emilio
authors.initials: E
authors.lastname: Ramos
mesh_terms: D001706:Biopsy; D005500:Follow-Up Studies; D006085:Graft Survival; D006801:Humans; D007672:Kidney Cortex / Q000473:pathology* / Q000821:virology; D016030:Kidney Transplantation / Q000009:adverse effects* / Q000473:pathology; D016133:Polymerase Chain Reaction; D011120:Polyomavirus / Q000302:isolation & purification*; D027601:Polyomavirus Infections / Q000473:pathology*; D012189:Retrospective Studies; D013997:Time Factors; D014184:Transplantation, Homologous / Q000473:pathology; D017211:Treatment Failure; D016896:Treatment Outcome; D014556:Urine / Q000821:virology; D019562:Viral Load