Pathology of the kidney allograft

The kidney biopsy still represents the best approach to diagnose renal transplant complications. It is considered the gold standard in the diagnosis of rejection and non-rejection complications. Although invasive, it is a safe procedure with a very low complication rate. With adequate sampling, changes related to antibody-mediated rejection (ABMR) and T-cell mediated rejection (TCMR) can be identified. However, the pathologist needs to be aware of the many other complications, not related to rejection, that can affect the allograft function. Examples include viral infections, drug toxicity, systemic diseases such as hypertension and diabetes, and recurrent or de novo glomerulopathy, among others. In this article, we review the recent classification of pathology of the kidney allograft, with reference to recent consensus reached at the most recent Banff renal allograft classification meetings, and also highlight common non-rejection complications of the kidney transplant.