C3 Glomerular Disease or Post infectious GN?

On kidney biopsy, resolving post infectious can be sometimes a common finding and differentiating it from the novel entity of C3 glomerulonephritis might be necessary. A recent article in KI by Sethi et al nicely summarize the entity of MPGN and how that is going to be linked with C3 glomerular disease(C3GN).  As we have discussed in prior posts and concept maps that MPGN pattern of injury should prompt a secondary cause and this article nicely illustrates that. It also ties in the alternative pathway diseases such as C3GN and dense deposit disease.
In terms of differentiating from Post infectious GN. In light microscopy, once can see exudative neutrophilic endocapillary proliferation compared to C3GN which is usually MPGN pattern of injury but sometimes can be mesangial or proliferative. In PIGN, usually one sees IgG, kappa, lambda and C3 but in C3GN, there should be only C3 primarily.  In electron structure, PIGN is classic subepithelial humps and subendothelial deposits. In C3GN, there are mostly sub endothelial and mesangial deposits and fewer of subepithelial deposits. More common to see double contour in this entity than in PIGN.
Glad to see a better understanding of this entity(MPGN) that is an enigma in glomerular disease world.


Take a look at this mini review in KI.