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Endocarditis Vasculitis Mimic — SCE Rheumatology MCQ

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HardVasculitisEndocarditis Vasculitis MimicSCE Rheumatology

A 60-year-old man presents with 6 weeks of fever, weight loss and arthralgia. Examination shows splinter haemorrhages, tender finger-pad nodules, splenomegaly and a previously undocumented regurgitant murmur. Urinalysis demonstrates blood and protein, serum C3 is reduced, and PR3-ANCA is positive at low titre. He has no upper respiratory tract or pulmonary manifestations. Which is the most likely underlying diagnosis?

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Correct answer: E — Infective endocarditis

The correct answer is infective endocarditis. The prolonged fever, new regurgitant murmur, splinter haemorrhages, tender finger-pad nodules and splenomegaly are strongly suggestive. Endocarditis can produce ANCA positivity and glomerulonephritis, commonly with immune-complex deposition and hypocomplementaemia, thereby mimicking ANCA-associated vasculitis. Absence of ENT or pulmonary disease and reduced C3 make primary granulomatosis with polyangiitis less likely. Cholesterol embolisation usually follows vascular instrumentation and causes livedo, digital ischaemia and eosinophilia. Polyarteritis nodosa does not cause glomerulonephritis, while late-onset SLE would not explain the characteristic cardiac and peripheral signs. Blood cultures and echocardiography are essential before immunosuppression, as treating occult infection as primary vasculitis can be dangerous.

Reference: Van Gool IC et al. Antineutrophil cytoplasmic antibodies in infective endocarditis: a case report and systematic review of the literature. Clinical Rheumatology. 2022;41:2949–2960. https://pubmed.ncbi.nlm.nih.gov/35732985/