Diagnose This (January 12, 2021)

What are the two major changes seen in this image from an allograft kidney and what are these findings concerning for?

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Answer: The light microscopic image of a glomerulus on silver stain demonstrates glomerulitis as characterized by capillary loop occlusion by mononuclear cells and neutrophils along with endothelial enlargement which is concerning for active antibody-mediated rejection. Other features used to diagnose antibody-mediated rejection, in this case, included severe peritubular capillaritis and diffusely positive C4d in peritubular capillaries.  The image also shows chronic changes of antibody-mediated rejection with multiple loops showing double contour formation. For more information on the Banff criteria for transplant rejection, see the following reference:

Reference: Loupy A, Haas M, Roufosse C, et al. The Banff 2019 Kidney Meeting Report (I): Updates on and clarification of criteria for T cell– and antibody-mediated rejection. Am J Transplant. 2020; 00: 1–14.