Fig. 3. Morphologic features of BK virus nephropathy. (A) Sharply demarcated geographic inflammation associated with focally infected tubular cells (arrows; Jones methenamine silver, ×40). (B) Prominent medullary viral infection and inflammation with no cortical involvement. Note the arcuate artery (arrow) between the medulla to the right of the artery and cortex to the left of the artery (Jones methenamine silver, ×100). (C) Plasma cell-rich mixed inflammation in areas of viral infection (Jones methenamine silver, ×400). (D) Focal macrophage aggregation (arrow) around an injured tubule (PAS, ×600).
