Fig. 1

Representative findings of tubulointerstitial changes in MCNS patients. a-f Vacuoles (a, arrow heads), hyaline droplets (b, arrow heads) and proteinaceous casts (b, asterisks) are observed in tubules. Tubular simplification, including loss of brush-border of the proximal tubule (b, arrow) and dilated tubule with flattening of tubular epithelium, is also observed. c Tubular necrosis is focally observed in a patient in the AKI group (asterisk). d Severe interstitial edema due to the expansion of intertubular spaces and dilated peritubular capillaries with tubular collapses is noted. H & E staining (e) and Masson’s trichrome staining (f) in consecutive sections. Tubules with tubular simplification (e) are situated on the thin tubular basement membrane that appears to be normal and is not surrounded by an accumulation of collagen fibres, as assessed by Masson’s trichrome-positivity (g: glomeruli; a-d, PAS staining; original magnification ×200).