Mesangial Deposits

Electron microscopy of a biopsy specimen in a patient with IgA nephropathy. Electron dense deposits can be identified in the mesangium (black arrows), which on immunofluorescence would have predominant or co-dominant IgA staining. Note that although mesangial IgA deposits are classic in IgA nephropathy and IgA vasculitis (former Henoch-Schonlein purpura nephritis), they can be seen in other conditions including infection-associated glomerulonephritis, inflammatory bowel disease, malignancies, sarcoidosis, and certain dermatologic conditions. GBM; glomerular basement membrane. RBC; red blood cells. Mes; mesangium. CS; capillary space. Images courtesy of Patrick Walker, MD.

Tubuloreticular inclusions in SLE nephritis

Tubuloreticular inclusions in a patient with diffuse proliferative SLE nephritis (SLE class IV). These subcellular structures (dark circular clusters) on transmission electron microscopy are localized to the cytoplasm of endothelial cells, and thought to be formed in high interferon states. These are classic for SLE nephritis, but can be seen in other glomerular conditions as well including membranous nephropathy, ANCA-associated vasculitis, and infection-associated glomerulonephritis.