Fig. 1.

Light microscopy findings in renal biopsy (patient 1). Most glomeruli show diffuse endocapillary hypercellularity and neutrophilic infiltration with cellular crescents. Tubulointerstitial changes are mild (periodic acid-Schiff [PAS]) (A). In high-power views, the glomerulus shows a cellular crescent as well as endocapillary hypercellularity (PAS) (B), diffuse mesangial and endocapillary hypercellularity (methenamine silver) (C), and subepithelial, 'hump'-like deposits (arrow) (Masson's trichrome) (D).