Yamashita M, Lin MY, Hou J, Ren KYM, Haas M: The Continuing Need for Electron Microscopy in Examination of Medical Renal Biopsies: Examples in Practice. Glomerular Diseases DOI 10.1159/000516831
Transmission electron microscopy (TEM) is often performed as a routine part of the pathologic examination of native kidney biopsies and also kidney transplant biopsies. However, this evaluative method is not generally available in many countries of the world and tissue specimen limitations may impact upon the ability to perform TEM in every case. Thus, it is important to understand the degree to which an accurate diagnosis of kidney disease is impaired when TEM is lacking.
Yamashita and coworkers have addressed this conundrum by describing 6 examples where TEM played a vital and irreplaceable role in determining an accurate diagnosis in a kidney biopsy. Minimal change disease, early membranous nephropathy, Alport syndrome, infection-related glomerulonephritis, immunotactoid glomerulonephritis, and collagen III glomerulopathy were the chosen examples. In each case the TEM findings were essential in making a correct diagnosis.
While this case-oriented paper makes a very good point, many other examples of the crucial value of TEM could have been included, such as the evaluation of the degree of foot process effacement in lesion of FSGS, the detection of “footprint” deposits pathognomonic of lupus nephritis, and the characteristic lesions by TEM in certain genetic diseases. Perhaps in the future the need for TEM studies will be diminished; for example, by expanded use of serum biomarkers such as DNAJB9 (for fibrillary GN) and panels of anti-podocyte antibodies for study of serum and immunofluorescence microscopy in membranous nephropathy. For the present, the recommendation to collect appropriately preserved specimens for future TEM in all cases of native and transplant kidney biopsies is good advice, when the prospect of immediate TEM is not feasible.