Importance of frequency and morphological characteristics of nodular diabetic glomerulosclerosis in diabetic nephropathy

The Renal Pathology Society proposed a pathological classification for diabetic nephropathy (DN) (RPS 2010). We retrospectively examined the renal structural-functional relationships using the RPS 2010 classification in 49 DN cases. We also evaluated the importance of the percentage of glomeruli with nodular diabetic glomerulosclerosis and their morphological characteristics (cellular, cellular and extracellular matrix [ECM] or ECM types) in the pathology of DN. The classes of DN (RPS 2010) were significantly correlated with the duration of diabetes mellitus (DM), degree of proteinuria, a decreased estimated glomerular filtration rate (eGFR), and the stages of Japanese clinical DM and chronic kidney disease (CKD). When the percentage of glomeruli with nodular glomerulosclerosis (IIIA <25%, IIIB 25-50%, IIIC 50-75%, and IIID >75%) was added to class III in this classification, the classes of DN had a greater correlation with the levels of proteinuria. The morphological characteristics of nodular glomerulosclerosis such as cellular, cellular and ECM, or ECM type were associated with several clinical parameters including the duration of DM, degree of proteinuria, a decreased eGFR, and/or the stages of clinical DM and CKD. Mesangial red blood cell fragments that is indicative of microvascular injury was found in cellular or cellular and ECM types of nodular glomerulosclerosis. The RPS 2010 classification is useful as a DN pathological classification that indicates a good correlation with the clinical characteristics of DN. In addition, the frequency and morphological characteristics of nodular diabetic glomerulosclerosis is important for the evaluation of the pathology in DN.