Fig. 1

a and b Light microscopy demonstrated diffuse membranous thickening within the glomerulus with abundant optically clear intracytoplasmic vacuoles, which ranged from predominantly large and coarse to fine, involving both the proximal tubular epithelial cells. The vacuoles appeared empty with all routine stains (including hematoxylin and eosin. Hematoxylin and eosin, original magnification × 40 for panel (a) and × 100 for panel (b). Scale bars 100 μm (a) and 20 μm (b). c Immunoflorescencent stain revealed diffuse global granular capillary loop staining for IgG. Scale bars 20 μm. The immunofluorescence stain was illustrated by Leica DM2500, Germany (d) Immunohistochemical stain revealed granular staining along basement membrane for PLA2R. Scale bars 20 μm. The light microscopy and immunohistochemical stain were illustrated by Nikon E600, Japan