Polyomavirus nephropathy in renal allograft: prevalence and correlation of histology with graft failure

While polyomavirus nephropathy (PVN) is recognized as an emerging cause of graft loss in renal transplants, the prevalence rate of PVN in renal grafts is unclear in Taiwan.

Biopsies (n = 412) from 323 Taiwanese renal transplant patients were retrospectively analysed. PVN was diagnosed by the characteristic viropathic change in epithelial cells under light microscopic examination and a positive immunohistochemistry staining of anti-SV40 large T antigen. The viral cytopathic changes, interstitial inflammation, fibrosis and tubular atrophy were semiquantitatively assessed, based on the Banff 1997 classification and scoring for renal allograft.

Seventeen cases were identified with evidence of PVN; the prevalence rate is 5.26%. Compared with non-PVN patients, they were more likely to have had previous rejection episodes, higher graft loss and shorter graft survival.

This retrospective study showed that we have similar findings to other reports with at least 5% prevalence of PVN and that patients diagnosed early do better, while those diagnosed with severe inflammation or damage do worse or are likely to lose their grafts.