Fig. 7. BK virus nephropathy before and after viral clearance. Time of BK virus nephropathy diagnosis with >2 million viral copies/mL plasma. (A) There is severe inflammation in the interstitium (i3) and in tubules (t3, arrow). Necrotic desquamated tubular cells with cytopathic changes are in several tubules (arrowheads; H&E, ×200). (B) Simian virus 40 (SV40) immunohistochemical stain showing extensive infection of tubular cells (arrowheads; ×200). Kidney biopsy was done 3.5 months later, following treatment with reduced immunosuppression, intravenous immunoglobulin G, and leflunomide, with 13 viral copies/mL plasma. (C) There is mild inflammation in the interstitium (i1) and in tubules (t1; arrows; PAS, ×200). (D) SV40 immunohistochemical stain shows no infected tubular cells (×200).
