Renal biopsy. A, B, C: Active diffuse proliferative lupus glomerulonephritis with cellular crescents (*) in 15 of 18 glomeruli, marked inflammation of the interstitium and signs of acute tubular necrosis (+). Please note that there is no chronic damage in the kidney. In Figure 1C also markedly thickened, stiff appearing glomerular basement membranes due to intramembranous and subepithelial immune deposits (arrow) are seen. Light microscopy, PAS Stain. Magnifications x 10 (A), x 20(B), x 40(C).