Electron microscopy in renal pathology: overall applications and guidelines for tissue, collection, preparation, and stains

Electron microscopy is a mainstay in the analysis of renal biopsies, where it is typically employed in a correlative fashion along with light and immunofluorescence microscopy. Despite the development of a growing armamentarium of molecular and biochemical analytic methods as well as new immunostains with a widening panel of immunoreactants, electron microscopy remains crucial to the diagnosis of a number of disorders involving the renal glomerulus, vasculature, and tubulointerstitial compartment. The number of renal biopsies continues to grow and the indications for these biopsies continue expanding together with our understanding of disease processes. Proper collection of biopsies and careful analysis of data emanating from diagnostic modalities, clinical information, imaging, gross and microscopic tissue analysis, including a wide range of ancillary studies, represent the essential paradigm for generating detailed diagnoses with clinical significance. This communication offers a guide to the pre-analytic and analytic process for renal biopsy examination, discusses diagnostic keys and pitfalls for an important category of renal diseases (immune complex disorders), and provides an introduction to a useful adjunct diagnostic method (ultrastructural immunolabeling). Renal pathologists should render expert diagnoses that guide patient management, provide prognostic information and lead to targeted new therapeutic interventions that are currently available.