Fig. 1

Patient renal biopsy findings. a Light microscopy showed some global sclerosis and segmental glomerular sclerosis along with focal tubular atrophy and interstitial inflammatory infiltration. (periodic methenamine silver and Masson trichrome staining, × 40). b Glomerular segmental sclerosis with cytoplasmic vacuolization of podocytes. (periodic acid-Schiff staining, × 200). c Cytoplasmic vacuolization and eosinophilic granules of proximal tubular epithelial cells. (hematoxylin and eosin, × 200). d The rod-like crystals in the cytoplasm of podocytes on EM (× 15,000). e Crystals in the proximal tubular epithelial cell on EM (× 12,000). f Immuno-electron microscopy (labeled by colloid gold particles with a diameter of 10 nm) indicated κ light chain deposition in the crystals without λ light chain (× 40,000)