The role of electron microscopy in renal allograft biopsy evaluation.

Purpose of review To review and discuss the use of electron microscopy in the examination of renal transplant biopsies, in particular its role in the diagnosis of glomerular disease and antibody-mediated rejection. Recent findings Electron microscopy can detect recurrent and de-novo glomerular disease at early stages, in particular for focal and segmental glomerulosclerosis and thrombotic microangiopathy. Ultrastructural features are an integral part of the Banff definition of chronic, active antibody-mediated rejection, which has been recently modified to include ultrastructural-only glomerular double contours. In addition, the threshold of peritubular capillary basement membrane multilayering diagnostic for chronic, active antibody-mediated rejection has been changed. As an area for further investigation, ultrastructural-only glomerular and peritubular capillary features could become tools in the early detection of antibody-mediated rejection. Summary Electron microscopy is important in the diagnosis of glomerular disease and chronic, active antibody-mediated rejection, both of which contribute to late graft loss. Early detection and treatment may help prolong graft survival. More data are needed on the early ultrastructural features of antibody-mediated injury, so that the usefulness of this technique can be compared with emerging technologies such as transcript analysis.