Studies of sequential kidney biopsies (KB) after the diagnosis of polyomavirus allograft nephropathy (PVN) are scarce and clinicopathological evolution of PVN poorly understood. In practice management is based on integration of viremia, creatinine and biopsy findings, which define multiple possible clinicopathological scenarios (CPS) (AJT 2013;1379).

The CPS at the first (1^st) and second (2^nd) KB were tabulated in 54 consecutive patients (pt) as follows: Viremia: A1,2,3,4 negative, decreasing, stable, increasing; creatinine (cr) B1,2,3,4 normal, decreasing, abnormal stable, increasing; SV40 KB status C1,2 positive, negative; and rejection in KB D1,2,3 negative, inconclusive, positive. Mean times for 1^st and 2^nd KB were 260 and 491 days, respectively.

A,B,C,D combinations lead to 160 potential CPS but only 13 and 20 actually occurred in 1^st and 2^nd biopsies, respectively (total 26). Five vs. 11 CPS accounted for ∼80% of possibilities in 1^st and 2^nd KB, respectively. In the 1^st KB 90.7% had increasing viremia and PVN was presumptive in 29.6%. Definite PVN was clinical 12pt(22.2%) and subclinical (normal cr) in 26pt(48.2%). At the 2^nd KB viremia was more variable and presumptive PVN occurred in 7pt(12.9%). At the 2^nd KB 17pt(31.48%) had cleared the virus (15 with abnormal cr) and 6 had rejection. Persistent PVN with SV40 positivity occurred in 30pt(55.5%, 23 with abnormal cr) and 7 had rejection. Post-transplant KB time did not correlate with CPS, and ABCD variables in 1^st KB did not predict values in 2^nd KB. Only BK viremia correlated in both KB(p=.003) and predicted abnormal cr overall (p=.02).

A limited number of CPS was found in the 1^stKB whereas a relatively larger number emerged in the 2^nd KB . Analysis of larger cohorts with systematic integration of the viremia, creatinine and biopsy results (SV40 status and rejection) may increase understanding of PVN and lead to development of more rational guidelines for follow-up.

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