Kidney histology in C4 dense deposit disease

Kidney histology in a patient with C4 dense deposit disease.
(Panels A and B) Light microscopy showing a membranoproliferative glomerulonephritis with mesangial hypercellularity, endocapillary proliferation, and thickened glomerular basement membranes (GBM). Note periodic acid Schiff (PAS)-positive thickened GBM in panel A (arrows point to positive thickened GBM) and B-silver methenamine stain in panel B.
(Panel C) Immunofluorescence microscopy showing bright staining for C4d along the capillary walls.
(Panel D) Electron microscopy showing dense osmiophilic deposits along the GBM (arrows point to the dense deposits).