TABLE 4.
Consensus recommendations: pathology
| • We recommend that in the context of detectable BKPyV-DNAemia, a kidney biopsy be performed as clinically indicated (eg, rise in serum creatinine, proteinuria, hematuria; strong, A) |
| • We suggest that in the context of detectable BKPyV-DNAemia and stable renal function, a kidney biopsy should be considered for patients at high immunological risk or high virologic risk (weak, D) |
| • We suggest that kidney transplant biopsies be interpreted in the context of clinical, laboratory, and virologic data and prior biopsy findings (weak, C) |
| • We recommend reporting the semiquantitative PyVL score to enable the classification into the Banff Working Group proposal (strong, C) |
| • We recommend the parallel reporting of the classification of the American Society of Transplantation (AST-PyVAN) using the 5 strata of PyVAN-A, -B1, -B2, -B3, and -C to accommodate inflammation and tubulitis (strong, C) |
| • We recommend that antibody-mediated rejection be diagnosed in a patient with detectable BKPyV-DNAemia if Banff diagnostic criteria are met (strong, C) |
| • We recommend that concomitant interstitial TCMR (Banff grade IA/B) is not diagnosed on the basis of inflammation and tubulitis; instead, an explanatory diagnostic comment incorporating interdisciplinary discussion should be used (strong, B) |
| • We recommend immunohistochemistry (clone PAb 416 against SV40 large T-antigen) for confirming the diagnosis of biopsy-proven PyVAN (strong, A) |
| • We recommend routine SV40 (LTag) immunohistology in patients with detectable BKPyV-DNAemia (strong, B) |
| • We suggest to use SV40 (LTag) immunohistology in patients with unknown BKPyV-DNAemia status with inflammatory changes in the biopsy (weak, D) |
| • We suggest to not use routine SV40 (LTag) immunohistology staining in patients with undetectable BKPyV-DNAemia (weak, C) |
| • We suggest to not perform an allograft biopsy during the course or resolution of BKPyV-DNAemia/-nephropathy unless rejection or another renal disease is a matter of concern and its detection will alter management (weak, D) |
| Future directions |
| ➢ Standardize immunohistochemistry protocols that can distinguish between different polyomaviruses, such as BKPyV, JCPyV, and other PyVs, including SV40 |
| ➢ Compare Banff PyVL and AST-PyVAN staging for capturing concurrent kidney allograft failure and predicting treatment response and allograft survival |
| ➢ Define clinically actionable thresholds of molecular tests of allograft biopsy viral loads that justify reduction in immunosuppression |
| ➢ Investigate how to best combine results from BKPyV-specific cell-mediated immunity with BKPyV-DNAemia and biopsy findings to optimize adjusting immunosuppression |
| ➢ Develop noninvasive assays that provide information equivalent to a kidney biopsy for staging BKPyV-nephropathy and forms of acute or chronic active rejection |
AST-PyVAN, American Society of Transplantation-polyomavirus-associated nephropathy; BKPyV, BK polyomavirus; JCPyV, JC polyomavirus; LTag, large tumor antigen; PyAN, polyomavirus-associated nephropathy; PyV, polyomavirus; PyVL, polyoma tissue viral load; SV40, simian virus 40; TCMR, T cell–mediated rejection.