Membranous glomerulonephritis: A morphometric study

Archival material from 45 renal biopsies with a diagnosis of idiopathic mem branous glomerulonephritis (MGN) were studied by computer-aided image analy sis in order to evaluate the prognostic significance of glomerular and inte rstitial morphometry in MGN. The control group consisted of thirty seven no rmal renal biopsy specimens. The surface area, the perimeter, the major axi s length and the shape factor of renal glomeruli as well as the percentage of the interstitial fibrosis were measured. All the morphometric parameters related to the size of glomeruli had signif icantly higher values in the patient group (p = 0.000 for all the parameter s). However, no significant difference of the glomerular size between diffe rent stages of MGN was observed. In contrast, the percentage of interstitia l fibrosis increased as the MGN stage rose (median values: 10.3% in stage 1 , 14.2% in stage II, 26.9% in stage III, 28.9% in stage IV and 34.2% in sta ge V, Kruskal-Wallis ANOVA H = 37.645, p = 0.000). In the multivariate anal ysis the percentage of interstitial fibrosis was the only independent progn ostic factor (p = 0.013). Our findings suggest that, in membraneous glomerulonephritis, the interstit ial fibrosis increases as the MGN stage progresses, while the size of renal glomeruli has increased at a very early stage of the disease. This fact ma y indicate that interstitial fibrosis, not glomerular lesions, is mainly re sponsible for the reduction of renal function.