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.