[Pathomorphological differential diagnosis of glomerular lesions in diabetics]

In renal biopsy specimens taken from 165 diabetics 3 cases with amyloidosis and 25 with glomerulonephritis (GN) were found. Among these were 13 cases with membranous and 10 with mesangial proliferative GN. This remarkably high rate may be partly due to selection, but, it can also be explained by the techniques of investigation because most of the GN cases were diagnosed by semithin sections and/or immune histology, respectively. In paraffin sections these alterations may be misinterpreted as diffuse glomerulosclerosis (GS), borderline lesions or normal findings. This is understandable because in mesangial proliferative GN, as well as in diffuse GS, the mesangium is broadened; similarly the spike formation or basement membrane doubling of membranous GN may simulate a thickening of the basement membrane. In addition, the differential diagnosis between GS and other diseases/lesions is discussed. We conclude that the examination of specimens by adequate methods will reveal "nondiabetic" glomerular lesions in diabetics more frequently than previously reported in the literature.