MPGN is a rare type of glomerulonephritis with typical immunohistochemical findings. This histomorphological classification is almost abandoned in favor of the more pathophysiologically oriented classification as C3 glomerulopathy in which the abnormal activation of the alternative complement pathway plays a crucial role. In connection with such pathophysiological considerations molecular genetic diagnosis gains importance.
Discrete immune complex deposition in the mesangium and subendothelial space with secondary activation of the classical complement pathway.
Continuous, electron-dense, ribbon-like, C3-rich deposition along glomerular basement membrane, tubular basement membrane, and Bowman's capsule. The cause is an over-activation of the alternative complement pathway.
Burkholder variant: Multiple subepithelial and subendothelial deposits.
Strife and Anders variant: Predominantly intramembranous deposits and disruption of the glomerular basement membrane.