Fig. 1

Diagnostic studies. (a) Periodic acid–Schiff (PAS) staining at a low magnification (× 100). All glomeruli exhibited lobular accentuation. (b–e) Glomerular images of (b) hematoxylin-eosin, (c) PAS, (d) Periodic acid–methenamine-silver, and (e) Masson’s trichrome staining (×400). Glomeruli show endocapillary hypercellularity with neutrophilic and eosinophilic infiltration. Scale bar: 100 μm (a) and 50 μm (b–e). (f) Immunofluorescence studies using frozen sections. Immunoglobulins were negative. C3 (1+) and C1q (2+) were positive on glomerular capillaries. (g) Electron microscopy image. Cross-sectional view of deposits with microtubular structures. The distribution of these structures was segmental. Scale bar: 200 nm. (h) IgG detection by paraffin-immunofluorescence following pronase pretreatment. The left panel is a glomerulus, and the right panel is a peritubular capillary. The positive signal in the microcapillary lumen was considered to be nonspecific staining for plasma components. (i) Immunofluorescence studies using anti-IgG (left panel, 55,144, MP Biomedicals) and anti-C4d (right panel) antibodies. IgG and C4d were positive on glomerular capillaries, corresponding to staining patterns for C3 and C1q