Classification Systems in Renal Pathology: Promises and Problems

Kidney diseases are morphologically heterogeneous. Pathologic classifications of renal disease permit standardization of diagnosis and may identify clinical-pathologic subgroups with different outcomes and/or responses to treatment. To date, classifications have been proposed for lupus nephritis, allograft rejection, IgA nephropathy, focal segmental glomerulosclerosis, antineutrophil cytoplasmic antibody -related glomerulonephritis, and diabetic glomerulosclerosis. These classifications share several limitations related to lack of specificity, reproducibility, validation, and relevance to clinical practice. They offer a standardized approach to diagnosis, however, which should facilitate communication and clinical research.