Thick tubular basement membrane duplication. Thick tubular basement membrane duplication was defined as thickness of >10 μm (yellow arrows). (a and b) Patient number 883, periodic acid–methenamine silver (PAM) stain, 20× and 40× magnification, respectively. (c and d) Patient number 478, PAM stain, 20× and 40× magnification, respectively. (e and f) Patient number 896, PAM stain, 20× and 40× magnification, respectively. All slides were scanned on the NanoZoomer NDP system with 40× resolution (0.23 μm/pixel) (Hama-matsu Photonics, Hamamatsu-City, Japan).