Comparison of Typical Endocapillary and Atypical Mesangial Proliferation in Postinfectious Glomerulonephritis

Background. There is a broad spectrum of glomerular histological findings in postinfectious glomerulonephritis (PIGN). We conducted this retrospective study to compare the clinicopathological features between two distinct morphology of PIGN. Methods. Thirteen patients with typical endocapillary proliferation and eight patients with atypical mesangial proliferation were enrolled in this study. The patients' records were reviewed with respect to clinical presentation, microbiology, serology, morphology of renal biopsy, and clinical course. Results. In comparison of histological parameters, glomerular neutrophil infiltration was more commonly present in typical endocapillary proliferation group (p = 0.018). Glomerular IgA dominant or co-dominant deposition was more frequently seen in atypical mesangial proliferation group (p = 0.032). In a comparison of clinical parameters, atypical mesangial proliferation group had lesser degrees of proteinuria, higher serum levels of complement, and higher rates of staphylococcal infection, although none of the differences was statistically significant. Glomerular morphology did not seem to affect the renal outcome. Moreover, our data suggested that the percentage of patients with atypical mesangial proliferation significantly increased over time (p < 0.001). Conclusions. Atypical mesangial proliferation may represent a resolution stage of PIGN. The nature of subclinical infection with a more protracted course may contribute to the increasing recognition of this resolving PIGN at the time of renal biopsy. Another possible explanation is that the atypical morphology may be a peculiar pattern of post-staphylococcal glomerulonephritis, which was increasingly identified in PIGN over the past 10 years.