Figure 3
Photomicrograph of the renal biopsy with a hematoxylin and eosin stain ×400 magnification showing a pauci-immune, focal necrotizing glomerulonephritis with one small crescent consistent with anti-neutrophil cytoplasmic antibody-associated vasculitis. Red cell casts are present. There is an interstitial infiltrate of lymphocytes, macrophages and eosinophils which involves some tubules. Immunofluorescence staining revealed mild mesangial deposition of immunoglobulin M and traces of mesangial C3.