Fig. 1

Renal biopsy. a hematoxylin and eosin (H&E) staining shows glomerular morphology noting increased cellularity and mesangial expansion (b and c). High magnification of periodic acid methenamine silver (PAM) staining shows the double loop sign (b and c, white arrow) and bubbling appearance (e, black arrow). d Fluorescence immunostaining shows granular deposition of complement C3 on the glomerulocapillary wall. e Electron microscopy shows mesangial cell proliferation and expansion (e, star) and electron dense deposits (subepithelial immune deposits) on the glomerular basement membrane intercalated into the mesangial cells (f, black arrow)