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. Image courtesy of Joseph Gaut, MD, PhD.