(A) Pathology of MGRS lesions with nonorganized deposits: MIDD. (a-f): Patient's kidney biopsy, light chain deposition disease. Glomeruli show mild mesangial sclerosis, with thickened capillary walls and Bowman's capsule membrane (a, PAS stain,  × 400). Mildly thickened tubular basement membranes show Congo red negative deposits (not shown) (b, trichrome stain,  × 400). On immunofluorescence, diffuse linear deposits of kappa light chains are seen in the mesangium, around capillary walls, and in the tubular basement membranes (c,  × 400), whereas no staining is observed for lambda light chain (d,  × 400). On EM, linear “powdery punctuate” deposits are visible on the outer aspect of tubular basement membranes (e,  × 10 000) and on the inner aspect of glomerular basement membranes (f,  × 15 000). LCDD: typical pattern of nodular glomerulosclerosis with aneurysmal dilatation of glomerular capillary loops (g, PAS stain,  × 400). LCDD: EM showing linear glomerular deposits stained with a gold conjugated anti-kappa light chain antibody (h,  × 30 000), without significant staining for lambda light chain (i,  × 10 000).