Successful treatment of infectious endocarditis associated glomerulonephritis mimicking c3 glomerulonephritis in a case with no previous cardiac disease

Abstract

We report a 42-year-old man with subacute infectious endocarditis (IE) with septic pulmonary embolism, presenting rapidly progressive glomerulonephritis and positive proteinase 3-anti-neutrophil cytoplasmic antibody (PR3-ANCA). He had no previous history of heart disease. Renal histology revealed diffuse endocapillary proliferative glomerulonephritis with complement 3- (C3-) dominant staining and subendothelial electron dense deposit, mimicking C3 glomerulonephritis. Successful treatment of IE with valve plastic surgery gradually ameliorated hypocomplementemia and renal failure; thus C3 glomerulonephritis-like lesion in this case was classified as postinfectious glomerulonephritis. IE associated glomerulonephritis is relatively rare, especially in cases with no previous history of valvular disease of the heart like our case. This case also reemphasizes the broad differential diagnosis of renal involvement in IE.

Figure 1

(a) Chest X-ray showing multiple bilateral nodular densities. (b) CT of the chest demonstrating bilateral multiple lung nodules, some of which are cavitated.

Figure 2

Transthoracic echocardiograph. Extensive bacterial vegetations are observed on the tricuspid (arrows) valves. RA: right atrium, RV: right ventricle.

Figure 3

Photomicrographs of renal tissue. (a) Light microscopy shows a diffuse endocapillary proliferative glomerulonephritis with lobular formation. PAS staining. Original magnification ×400. (b) Bright C3 staining along capillary walls by immunofluorescence. (c) Electron microscopy shows polymorphonuclear cells and monocyte infiltration in the capillary wall. Bar = 2.0 µm. (d) The area of the square in Figure 3(c) shows subendothelial deposits (arrows). Bar = 0.2 µm.

Figure 4

Clinical course after admission.