PMC3292813_01
First renal biopsy specimen. On the first biopsy the glomerulus is globally hypercellular, with numerous intracapillary mononuclear cells. A small artery has intimal thickening with scattered infiltrating mononuclear cells, together with segmental medial disruption and perivascular fibrosis, indicating vasculitis (hematoxylin and eosin). This renal vasculitis is characterized by segmental fibrinoid necrosis associated with 35% crescents. Diffuse mesangial endocapillary proliferation and inflammatory cells infiltration is observed as well, consistent with crescentic glomerulonephritis.
1752-1947-6-39-1.jpg
PMC3292813_01_1752-1947-6-39-1.jpg
F1
Diffuse mesangial endocapillary proliferation and inflammatory cells infiltration were observed as well, consistent with cryoglobulinemic glomerulonephritis (Figure 1).
Second renal biopsy specimen. A second renal biopsy was performed at the end of the treatment (six months of antiviral therapy and 24 plasma exchange therapies). The immunofluorescence pattern shows intense massive staining of the deposits totally filling the capillary lumina. Faint and irregular parietal deposits also are present along peripheral glomerular loops. The components of mixed cryoglobulinemia immunoglobulin M, usually associated with C3, are the most frequently found immunoreactants.
1752-1947-6-39-2.jpg
PMC3292813_01_1752-1947-6-39-2.jpg
F2
I membranoproliferative glomerulonephritis (lobular mesangial proliferation, double-contours and persistence of inflammatory cells infiltration), finally confirming a diagnosis of MC vasculitis. Immunofluorescence staining showed IgM and C3 discontinuous granular deposits along the peripheral glomerular loops (Figure 2).