Libman-Sacks endocarditis (LSE) is a rare non-bacterial thrombotic endocarditis (NBTE) characterised by sterile valvular vegetations. It is most associated with systemic lupus erythematosus (SLE), antiphospholipid syndrome (APS) and malignancy. Diagnosis remains challenging as LSE often remains asymptomatic until embolic complications occur.

This report presents the case of a woman in her 50s initially presenting with abdominal pain secondary to pancreatitis and persistent fevers of unknown origin. Despite extensive investigation, including multiple negative blood cultures, no infectious source was identified. Moreover, multiple courses of broad-spectrum antibiotics were producing no clinical improvement. Subsequent transthoracic echocardiography demonstrated a small, mobile, valvular vegetation suggestive of endocarditis, with further assessment producing a clinical diagnosis of the rare LSE subtype. Notably, the patient had no peripheral stigmata of endocarditis, and LSE represented the first manifestation of previously undiagnosed SLE in the context of an underlying connective tissue disorder.

During the hospital course, the patient developed additional manifestations of SLE, including cutaneous lupus erythematosus and lupus nephritis. Autoimmune serology was strongly supportive of SLE. Treatment consisted of corticosteroids, hydroxychloroquine and mycophenolate mofetil, resulting in clinical improvement.

This case is notable as LSE being a first presentation of previously undiagnosed SLE. It highlights the importance of having high suspicion for LSE in patients with culture-negative endocarditis, persistent unexplained fever, and a background of autoimmune disease.

Rafia Ayub achieved her MBBS and BSc with Honours at St George’s University of London. She has completed Foundation Training at Manchester University NHS Trust and is currently a Postgraduate Clinical Education Fellow at St Heliers & Epsom University NHS Trust. She has 3 publications and multiple impactful quality improvement projects within her portfolio, and is looking towards Internal Medicine Training, with aspirations to become a Geriatrician.