Kawasaki disease (KD) is an acute systemic vasculitis that and a leading cause of acquired heart disease in children. In infants younger than 6 months, incomplete forms are frequent and are associated with a higher risk of coronary complications due to delayed diagnosis. We report the case of a 3-month-old infant presenting with prolonged high-grade fever, initially treated as a severe bacterial infection. Retrospective identification of transient mucocutaneous signs, together with persistent inflammatory syndrome and extreme thrombocytosis, led to further investigations. Echocardiography revealed multiple coronary aneurysms. A diagnosis of incomplete Kawasaki disease was established. Combined treatment with intravenous immunoglobulins, corticosteroid therapy, aspirin, and anticoagulation resulted in rapid improvement. This case highlights the diagnostic challenges of incomplete KD in young infants and shows that a favorable outcome with partial regression of coronary lesions can be achieved, even in the presence of a giant coronary aneurysm, when appropriate management is instituted.
Keywords: Kawasaki disease; coronary artery aneurysm; incomplete Kawasaki disease; infant; prolonged fever.
© The Author(s) 2026. Published by Oxford University Press.