Abstract: PUB172
Infective Endocarditis-Associated Crescentic Glomerulonephritis Masquerading as Drug-Induced Vasculitis: A Case Report
Session Information
Category: Glomerular Diseases
- 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics
Authors
- Itchon, Samantha J., Henry Ford St John Hospital, Detroit, Michigan, United States
- Peniston, Michael J., Henry Ford St John Hospital, Detroit, Michigan, United States
- Topf, Joel M., Henry Ford St John Hospital, Detroit, Michigan, United States
- Henderson, Heather Lynn, Henry Ford St John Hospital, Detroit, Michigan, United States
- Bellovich, Keith A., Henry Ford St John Hospital, Detroit, Michigan, United States
Introduction
Infection-associated glomerulonephritis (IAGN) due to infective endocarditis (IE) can mimic ANCA-associated vasculitis due to overlapping serologic and histopathologic findings. Distinguishing these entities is critical, as management strategies diverge significantly.
Case Description
A 59-year-old male with bicuspid aortic valve presented with dyspnea, 30-lb weight loss, and anemia. Evaluation revealed acute kidney injury, proteinuria (UACR 355 mg/g), and hypocomplementemia. Echocardiography demonstrated severe aortic stenosis with a mobile valvular mass, and blood cultures grew Streptococcus mutans, confirming IE.
Serologic workup showed dual ANCA positivity (PR3 and MPO), raising concern for drug-induced ANCA-associated vasculitis despite no identifiable drug exposure. Due to wrsening renal function and atypical features, kidney biopsy was performed and demonstrated crescentic glomerulonephritis with full-house immunofluorescence. The patient was treated with antibiotics, corticosteroids and subsequent aortic valve replacement. Renal function improved with creatinine decreasing to 1.13 mg/dL on follow-up, although ANCA titers remained elevated.
Discussion
ANCA positivity has been reported in up to 40% of IE-associated GN cases and may occur with crescentic histology, closely resembling pauci-immune vasculitis. PR3 positivity is more commonly reported than MPO or dual-positive serologies. However, findings such as hypocomplementemia and active infection favor IAGN. Misdiagnosis may lead to inappropriate immunosuppression and worsening infection.
Full-house pattern immunofluorescence is a biopsy finding classically associated with lupus nephritis. Non-lupus full house nephropathy has been identified as a distinct clinical syndrome in which kidney biopsy reveals full-house immunofluorescence resembling lupus nephritis, but without clinical or serological evidence of systemic lupus erythematosus. IAGN has been reported as a secondary cause of non-lupus full house nephropathy in various case reports, including this particular case.
IE-associated GN should be strongly considered in patients with ANCA positivity and concurrent infection. This case underscores the importance of clinicopathologic correlation to avoid misdiagnosis and to guide appropriate, and often competing, therapeutic strategies.