CMV/BKVco-infection has been reported as an uncommon and severe complication, manifested as tubulointerstitial nephritis in KT. We report 2 cases 1-61yold male CRF2º to ADPK. KT DD on 02/2019.CMV pretx D+R+.Induction:antithym-globulin. Maintenance: Belatacept, mycophenolate MPT.2ºm post tx had asthenia, adinamia, painful ulcers in the jugular and lingual mucosa, neutropenia and anemia. CMV PCR 840 copies. Began treatment with valganciclovir. Mycophenolate was suspended BKV PCR (2m)45600. Given viral infection associated with renal dysfunction a renal tx biopsy was performed. OM:8 glomeruli 2 globally sclerosed. Permeable glomeruli showed expansion of mild-grade mesangial matrix. Interstitium showed mild inflammatory infiltrate 20% tubular atrophy and interstitial fibrosis. Tubules presented severe alterations at lining epithelium. Clear intranuclear inclusions, nuclear hypertrophy and nuclei surrounded by a clear circumferential halo (owl's eye) are recognized. Immunohistochemistry for CMV 20% and SV40 15%.C4d -IF: (5) glomeruli. No hierarchy deposits. EM:(3)glomeruli had focal fusion of the podocyte feet. Viral virions were observed at the level of the nuclei of the tubular cells. He was discharged with mTor/MTP/leflunomide and his allograft function improved. Valganciclovir was given for 4w till subsequent testing for CMVPCR was undetectable and BKVN was treated with IVIG and BKPCR was undetectable 3 m later. 2-38y old female Hypersensitized. KT DD 01/2019.CMV pretx was D+R+ Induction: antithymocyte globulin/ IVIG. Maintenance tacro/mycophenolate/MPT. Persistence of DGF a graft biopsy showed mixed rejection being treatment with PMF/IVIG improving renal function. 3 m postxt oral ulcers, diarrhea and febrile syndrome were compatible with CMV infection(54,281 copies) receiving valganciclovir and suspending mycophenolate. 60d later CMVPCR was -. When  mycophenolate was reincorporated, she presented CMV(285 copies) and BKV (4500 copies) reactivation. A renal biopsy was performed: OM:8 glomeruli. Interstitium with moderate infiltrate of plasma cells without tubulitis or capillarity. 35% tubular atrophy and interstitial fibrosis. Tubules presented clear intranuclear inclusions, nuclear hypertrophy and nuclei surrounded by circumferential clear halo. SV40 30% and 20% for CMV.C4d - IF: 7 glomeruli without deposits of hierarchy. EM: fusion of podocyte feet. Viral virions were observed in tubular cell nuclei. Mycophenolate were suspended switching to Tacro, MTP, leflunomide. 30d later she had graft dysfunction (cr 5.1) a biopsy showed: ACCR IFTA 40% C4d-.S he received 3 MTP pulses and reduced cr at 2,3mg/dl.BKPCR was undetectable 2m later while CMVPCR persisted +(440 copies).
Conclusion: Reactivation of CMV and BK can result in virus-associated tubulointerstitial nephritis in renal allografts and could be an important cause of graft dysfunction. The gold standard for the diagnosis is identification of inclusions or BK/CMV-specific immunohistochemistry staining on histopathology.