Unique clinical entity: Infective endocarditis with ruptured MCA mycotic aneurysm presented as fever of unknown origin: Case report and literature review

INTRODUCTION AND IMPORTANCE: Fever of unknown origin (FUO) in children poses a complex challenge for doctors. It involves a broad spectrum of potential diagnoses, with infectious diseases being the predominant culprits, followed by connective tissue disorders and malignancies. CASE PRESENTATION: A 4-year-old boy with a prior diagnosis of a congenital bicuspid aortic valve was admitted to our hospital after experiencing two months of intermittent high-grade fever, severe nighttime headaches, and episodes of nausea and vomiting. His condition deteriorated rapidly with a drop in hemoglobin, elevated inflammatory markers, and the discovery of a large intracerebral hematoma. Further evaluation revealed infective endocarditis and a ruptured cerebral mycotic aneurysm associated with the bicuspid aortic valve infection. The aneurysm was successfully treated through cerebral endovascular catheterization, and the patient received six weeks of intravenous antibiotics. Cardiac surgery for valve repair was planned for a later date. CLINICAL DISCUSSION: Among the infectious causes, infective endocarditis (IE) is a notable contributor, accounting for 1–5 % of all FUO cases. IE can lead to severe complications, with a small fraction of patients experiencing neurological issues such as stroke, encephalopathy, or the development of cerebral mycotic aneurysms. CONCLUSION: The presented case serves as a stark reminder that FUO can be caused by serious underlying conditions, such as infective endocarditis. The rapid progression from fever and neurological symptoms to a ruptured cerebral mycotic aneurysm highlights the potentially life-threatening nature of these cases.