Renal tubular nuclear inclusions have a ground-glass appearance with irregular central clearing, or a coarse, vesicular appearance. Distal tubules are involved more often than proximal tubules. There may be only medullary involvement in early stages, and parietal epithelial cells may be involved in later stages of the infection. Infected epithelial cell nuclei stain with antibody to the large T antigen of the SV40 virus, which serves as a surrogate marker of human polyomavirus infection. [from
HPO]