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

Native and prosthetic valve infective endocarditis complicated by rapidly progressive glomerulonephritis and its diagnostic challenges and therapeutic implications

Key Clinical Message

Concomitant native and prosthetic valve infective endocarditis (IE) is very rare, and both can rarely be complicated by rapidly progressive glomerulonephritis (RPGN). This diagnosis has therapeutic implications, as not all RPGN need immunosuppression therapy.

Abstract

Native and prosthetic valve infective endocarditis (IE) may be rarely complicated by rapidly progressive glomerulonephritis (RPGN). The diagnosis of IE as a cause of RPGN may be missed, and patients may be subjected to inappropriate immune suppressive therapy. Moreover, IE involving multi-valves has rarely been described, and there are only few case reports of simultaneous native and prosthetic valve endocarditis. Here, we present a case of 34-year-old female patient who has RPGN and whose initial workup missed IE. However, further workup revealed a diagnosis of native and prosthetic valve IE and our patient, who would have been subjected to inappropriate immune suppressive therapy, was treated with intravenous antibiotics alone and discharged with improvement.

Proteinase‑3‑antineutrophil cytoplasmic antibody‑associated vasculitis secondary to subacute infective endocarditis: A case report

A 58-year-old male patient was admitted to Peking University First Hospital (Beijing, China) due to recurrent hematuria, proteinuria and kidney dysfunction. The patient was positive for proteinase-3 (PR3)-antineutrophil cytoplasmic antibody (ANCA). Pathology of the kidney showed focal proliferative necrotizing glomerulonephritis with crescent formation and immune complex-mediated glomerulonephritis. The patient was diagnosed with PR3-ANCA-associated vasculitis (AAV), received intensive immunosuppressive therapy and experienced two relapses within 1 year. After admission, aortic valve vegetation was observed via echocardiography. The patient subsequently received antibiotic treatment and valve replacement, and achieved complete remission of kidney and cardiac function. The present case emphasized the importance of identifying secondary reasons for ANCA formation, especially infective endocarditis in patients with PR3-AAV.

Vaskulitis mimics

Idiopathische Vaskulitiden sind seltene entzündliche Systemerkrankungen, die nach der Chapel-Hill Konsensus-Nomenklatur nach der Größe der prädominant betroffenen Gebiete von Blutgefäßen (große, mittelgroße, kleine Gefäße und Gefäße variabler Größe) eingeteilt werden. Vaskulitis mimics sind Syndrome, die ein ähnliches klinisches Bild hervorrufen oder leicht mit einer idiopathischen Vaskulitis verwechselt werden und teils sogar ein Krankheitsbild, das klinisch und histologisch einer Vaskulitis gleicht, auslösen können. Die Zahl der Vaskulitis mimics ist groß, je nach betroffenem Gefäßgebiet kommen hereditäre Erkrankungen des Bindegewebes, genetisch bedingte Immundefekt- und Autoinflammationssyndrome, infektiöse Erkrankungen, seltene entzündliche Systemerkrankungen, Tumorerkrankungen, medikamenteninduzierte Syndrome und zahlreiche weitere infrage. In diesem Review wird eine Auswahl klassischer Imitatoren von Vaskulitiden, orientiert an der Größe der betroffenen Blutgefäße präsentiert und Konstellationen, die typische „Fallstricke“ in der klinischen Abklärung darstellen können, diskutiert.

Characteristics and Diagnostic Challenge of Antineutrophil Cytoplasmic Antibody Positive Infective Endocarditis

OBJECTIVE

Antineutrophil cytoplasmic antibody (ANCA) has been reported in patients with infective endocarditis. Whether ANCA is associated with certain characteristics of infective endocarditis is unclear. The principal aim of this study is to investigate the clinical implications of ANCA in infective endocarditis and highlight the diagnostic challenge in ANCA-positive patients with infective endocarditis.

METHODS

A retrospective study was conducted in a tertiary hospital in China from August 2012 to December 2021. Patients with a diagnosis of infective endocarditis and available ANCA results were included in the study. The clinical and pathological characteristics were compared between ANCA-positive and ANCA-negative patients.

RESULTS

A total of 237 patients were included. Forty three (18.1%) were ANCA-positive, predominantly c-ANCA/anti-PR3. Compared to ANCA-negative patients, ANCA-positive patients had longer disease duration (P = .004), more frequent purpura (P = .015), macrohematuria (P = .002), proteinuria (P = .043), acute kidney injury (P = .004), and rapidly progressive glomerulonephritis (P = .010). Histologic findings of 8 patients with infective endocarditis-associated glomerulonephritis were reviewed. Two ANCA-positive patients with infective endocarditis presented with pauci-immune necrotizing and crescentic glomerulonephritis. A total of 18.6% of ANCA-positive patients with infective endocarditis were misdiagnosed as ANCA-associated vasculitis.

CONCLUSIONS

ANCA is detected in a substantial proportion of patients with infective endocarditis. The presence of ANCA in infective endocarditis is associated with longer disease duration, more frequent purpura, and kidney involvement. ANCA-positive infective endocarditis may mimic ANCA-associated vasculitis, and the differential diagnosis is challenging. Whether ANCA is pathogenic in infective endocarditis-associated small vessel vasculitis requires further study.