Clinicopathological features of polyomavirus-associated nephropathy / 中华肾脏病杂志

ABSTRACT

Objective To interpret the clinicopathological features and the key factors for diagnosis of polyomavirus-associated nephropathy (PVAN).Methods Clinicopathological data of 13casesof polyomavirus-associatednephropathyduring2008-2011inour hospitalwere retrospectively analyzed.Three cases received repeat biopsy.The clinicopathological features were analyzed according to thelight microscopicsceneandSV40-Timmunochemicalexpression.Results Recipients had a peak incidence of PVAN in 12 to 18 months period after renal transplantation,accompanied by elevated serum creatinine.Due to the progression of the disease,3patterns of histological findings could be identified.The early lesion was confined to the collected ducts,with slightly inflammatory infiltration in medullary interstitium,viral inclusions were not necessarily seen.The only findings could be enlarged nuclear and irregular arrangement of the tubular epithelial cells.At the developing stage,prominent tubulointerstitial nephritis was detected,and the involved tubules extended to other segments of renal tubule,even the parietal epithelial cells of Bowman's capsule could be compromised.The epithelial cells shed off,leading the tubular basement membrane exposed.Typical intra-nuclear inclusions as well as variable nuclear changes were found.At the end stage,the allograft showed notable chronic tubulointersititial change,with diffuse tubular atrophy and interstitial fibrosis.Although in this period,typical viral inclusions were rare, stillIHCshowedpositiveexpression of SV40-T. After immunosuppressantreductionor exchange,2 cases developed renal failure,4 cases showed sustained increment in serum creatinine,while 7 cases had a stabilized serum creatinine level.Conclusions Polyomavirus-associated nephropathy can display uneven pathological changes,as well as the morphology of the infected epithelial cells.Segments of the involved tubule are associated with the course of disease.Reduction of immunosuppressant at the early stage has a favorable effect.A prompt renal biopsy should be done in renal transplant recipient if who shows increased serum creatinine,and a routine polyomavirus immunohistochemical staining should be applied as well.