Endocarditis-associated rapidly progressive glomerulonephritis mimicking vasculitis: a diagnostic and treatment challenge

Abstract

Background: Infective endocarditis (IE)-associated rapidly progressive glomerulonephritis (RPGN) is rarely reported. Sporadic case reports have noted the diagnostic and therapeutic challenge in IE-associated glomerulonephritis because it may masquerade as idiopathic vasculitis.

Methods: Patients with clinical diagnosis of IE-related RPGN in a tertiary hospital in China between January 2004 and May 2021 were identified and retrospectively reviewed.

Results: Twenty-four patients with IE-associated RPGN were identified. All patients presented with fever and multiorgan system involvement on top of heart and kidneys, spleen (79%, 19/24), skin (63%, 15/24), lung (33%, 8/24) and nervous system (17%, 4/24). Six of the 24 patients (25%) were initially suspected to have ANCA-associated or IgA vasculitis. Forty-five percent of patients are seropositive for ANCA. Renal histology showed mesangial and/or endocapillary hypercellularity with extensive crescents in most patients. C3-dominant deposition was the predominant pattern on immunofluorescence and pauci-immune necrotising crescentic glomerulonephritis was observed in one case. All patients received antibiotics with or without surgery. Six patients received immunosuppressive therapy before antibiotics due to misdiagnosis and seven patients received immunosuppressive therapy after antibiotics due to persistence of renal failure. Three of the 24 patients died due to severe infection. All the surviving patients had partial or complete recovery of renal function.

Conclusion: IE-associated RPGN is rare and the differential diagnosis from idiopathic vasculitis can be challenging due to overlaps in clinical manifestations, ANCA positivity and absence of typical presentations of IE. The prognosis is generally good if antibiotics and surgery are not delayed. The decision on introducing immunoruppressive treatment should be made carefully on a case by case basis when kidney function does not improve appropriately after proper anti-infective therapy.Key messagesInfective endocarditis associated RPGN is rare and differentiating it from idiopathic vasculitis can be challenging due to overlap in clinical manifestations, ANCA positivity and occasional absence of typical manifestations of infective endocarditis.Kidney function usually responds to antibiotic therapy alone.Immunosuppressive therapy may be beneficial in carefully selected patients whose kidney function does not improve with antibiotics alone.

Keywords: Infective endocarditis; RPGN; immunosuppressive therapy; vasculitis.

Figure 1.

Representative light microscopy findings. (A) Large global cellular crescent (periodic acid-silver methenamine × 200). (B) Small cellular crescent (periodic acid-silver methenamine × 200). (C) Glomerulus with necrotising crescent (periodic acid-silver methenamine × 200). (D) Mesangial and endothelial hypercellularity (haematoxylin and eosin × 400). (E) Mesangial hypercellularity (haematoxylin and eosin × 400). (F) Endocapillary proliferative glomerulonephritis (periodic acid-silver methenamine × 400).

Figure 2.

Representative immunofluorescence microscopy findings. (A) Glomerulus with predominantly mesangial staining by C3. (reprinted from Am J Med. 2021;134(12):1539-1545.e1, with permission from Elsevier) (B) Glomerulus with mesangial and capillary wall staining by C3.

Figure 3.

Representative electron microscopy findings. (A) Subendothelial electron-dense deposits (arrow). (B) Mesangial electron-dense deposits (arrow).

Figure 4.

Changes of serum creatinine (SCr) in patients with rapidly progressive glomerulonephritis. D0 indicates the day of commencing antibiotics. Last FU indicates the last follow up. (A) Changes of SCr in 10 surviving patients without immunosuppressive therapy. (B) Changes of SCr in 11 surviving patients with immunosuppressive therapy.