case_images: PMC10328171_01
case_images: Timeline of the case report.
case_images: 10.1177_23247096231184770-fig1.jpg
case_images: PMC10328171_01_10.1177_23247096231184770-fig1.jpg
case_images: fig1-23247096231184770
case_images: A timeline of the case report is shown in Figure 1.
case_images: (A) Renal biopsy showing acute tubular injury with tubulointerstitial inflammation and viral cytopathic effect (arrow) (hematoxylin and eosin stain, original magnification 400x). (B) Renal biopsy showing tubular epithelial cells with focal positive simian virus 40 immunohistochemical stain for polyomavirus. An area of focal positive staining is denoted with an "*" (original magnification 100x).
case_images: 10.1177_23247096231184770-fig2.jpg
case_images: PMC10328171_01_10.1177_23247096231184770-fig2.jpg
case_images: fig2-23247096231184770
case_images: These findings were consistent with polyomavirus nephritis, class I (Figure 2).
case_images: Trend of the patient's serum creatinine and BK viral load over time during the preceding year. Day 0 represents baseline creatinine. The patient was diagnosed with unilateral hydronephrosis on day 115 and underwent unilateral ureteral stenting at that time. The patient underwent kidney biopsy and was diagnosed with BK nephropathy on day 240. Treatment was initiated at that time. Despite a reduction in immunosuppression and initiation of leflunomide, the viral load remained detectable with a nadir of 13 000 IU/mL, and the patient continued to have deteriorating renal function.
case_images: 10.1177_23247096231184770-fig3.jpg
case_images: PMC10328171_01_10.1177_23247096231184770-fig3.jpg
case_images: fig3-23247096231184770
case_images: BK viral load improved but remained detectable, dropping to 13 000 copies/mL 3 months after the initial reduction of immunosuppression and initiation of leflunomide (Figure 3).