20.500.12556/DiRROS-30848 Case report: Late-onset BK polyomavirus-associated nephropathy in kidney transplant recipients two cases and insights into underlying mechanisms BK polyomavirus–associated nephropathy (BKPyVAN) results from primary infection or reactivation of BK polyomavirus (BKPyV) and remains a significant complication in kidney transplant recipients, contributing to allograft dysfunction and premature allograft loss. Most cases occur within the first 2 years post-transplant, when cell-mediated immunity is most suppressed due to induction immunosuppression. Here, we describe two unusual cases of late-onset BKPyVAN occurring in the absence of intensified immunosuppression and provide a review of potential mechanisms underlying its development in kidney transplant recipients. In the first patient, BKPyVAN developed 9 years after transplantation during maintenance dual immunosuppression with tacrolimus and mycophenolic acid, without prior rejection episodes or exposure to intensified immunosuppression. In the second patient, BKPyVAN first occurred 3 years post-transplant in the setting of concomitant cytomegalovirus colitis, also during dual immunosuppression with tacrolimus and mycophenolic acid. Despite reduction of immunosuppression, BKPyVAN persisted at 1-year follow-up and was associated with a gradual decline in allograft function. These cases highlight that late-onset BKPyVAN may develop even without intensified immunosuppression and can lead to significant allograft injury. Improved strategies are needed to identify patients at risk for late-onset BKPyVAN and to optimize therapeutic management. BK polyomavirus-associated nephropathy diagnosis immunosuppression kidney transplantation pathophysiology true false true Angleški jezik Ni določen Neznano 2026-07-07 10:47:32 2026-07-07 10:47:32 2026-07-17 03:43:14 0000-00-00 00:00:00 2026 0 0 Nasl. z nasl. zaslona; Opis vira z dne 7. 7. 2026; Str. 1-9 [article no.] 1799421 Vol. 13 2026 0000-00-00 Zaloznikova Objavljeno apc 0000-00-00 0000-00-00 0000-00-00 616.61 2296-858X 10.3389/fmed.2026.1799421 283840515 RAZ_Belcic_Mikic_Tanja_2026.pdf RAZ_Belcic_Mikic_Tanja_2026.pdf 1 B2281CA276D29F6FD4C40AB45721CA9C 40dced5db9df04cac65dfa304580f6a486ac64fe2717b00ffc8a45c589b7e6cd 6abd19aa-80d3-11f1-aa99-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=48066 https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2026.1799421/full 1 7f76de04-79e0-11f1-a65c-001a4af901a5 https://dirros.openscience.si/Dokument.php?lang=slv&id=47257 Univerzitetni klinični center Ljubljana 0 0 0