Light microscopy, immunohistochemistry and electron microscopy of MPGN with intracapillary IgM thrombi with lambda light-chain restriction. (A) Periodic-acid Schiff (PAS) staining (400x) with numerous intracapillary PAS positive thrombi and prominent intracapillary and mesangial proliferation, (B) Silver staining with double contoured basement membranes as highlighted in the inlay (400x), (C) IgM immunohistochemistry with strong staining of the thrombi and basement membranes (400x). (D) CD68 immunohistochemistry showing dense mesangial and intracapillary infiltration of the glomeruli by monocytes/macrophages (400x). (E) lambda (400x) and (F) kappa (400x) light-chain immunohistochemistry with a lambda light-chain restriction in the thrombi. Inlays show thrombi (630x). (G) Electron microscopy showing a basement membrane with segmental cellular interposition and subendothelial and intramembranous electron-dense deposits as well as an intracapillary thrombus (3597x). (H) The electron-dense deposits show a granular structure. No tubulo-reticular structures are present (21560x, inlay 60000x). Magnifications are indicated as original magnifications.