Fig. 1

Findings in the first (a-f) and second biopsy (g-l), which is summarized in m. a Prominent endocapillary hypercellularity with infiltrating leukocytes. Arteriolitis in the glomerular hilus (indicated by circle) (El-M staining, magnification × 400). b Neutrophil infiltration and fibrosis in the interstitium. PTCitis included abundant neutrophils (indicated and zoomed by box) (HE staining, magnification × 100). c Weak fine granular C3c deposition was observed in the capillary wall. d Diffuse endocapillary proliferation and mesangiolysis was observed. Neither hump lesions nor apparent electron dense deposit was observed. Foot process effacement of the epithelial cells was globally observed (magnification × 2000). e NAPlr deposition was observed in the mesangium, subendothelial area and neutrophils. f Plasmin activity was distributed the same as in e. Both findings in e and f were limited in the tuft area and negative at the arteriole in hilus of glomerulus (indicated by circle). g Disappearance of endocapillary proliferation. Shrinking and double contour of capillary wall was globally apparent (El-M staining, magnification × 200). h Massive diffuse interstitial fibrosis and tubular atrophy. There were no findings of active arteritis. (El-M staining, magnification × 40). i C3c deposition was observed predominantly in the mesangial area. j Large subepithelial electron-dense deposits regarded as hump lesions were observed with various densities (indicated by arrowhead). None of them contained an organized structure (indicated and zoomed by box) (magnification × 1500). k NAPlr deposition was faded out and localized segmentally. l Plasmin activity was faded out the same as in k. m Summary of pathologic findings. HE: Hematoxylin eosin, PAM: Periodic acid-methenamine silver, PAS: Periodic acid-Schiff, El-M: Elastic-Masson