Atypical Kawasaki disease with giant coronary artery aneurysms in a 2-month-old boy: a case report.

Background: Kawasaki disease is an acute inflammatory disorder primarily affecting medium-sized blood vessels, especially in infants and young children under 5 years old, characterized by inflammation of the arterial walls, including coronary arteries. While predominantly affecting young children, rarely Kawasaki disease is seen in adults. Reporting this case is crucial due to the patient's very young age and the disease's unusual presentation following vaccination, contributing to the limited literature on Kawasaki disease in very young infants.

Case presentation: A full-term, 2-month-and-10-day-old Iranian boy presented with persistent fever unresponsive to treatment, beginning 5 days after receiving the 5-in-1 vaccine. Although physical examination results were normal, his medical history included maternal hypothyroidism during pregnancy and neonatal jaundice that did not require hospitalization. Initial laboratory tests revealed bicytopenia, thrombocytosis on the complete blood count, and elevated erythrocyte sedimentation rate and C-reactive protein levels. Echocardiography identified giant coronary artery aneurysms. The patient was diagnosed with atypical Kawasaki disease and treated with intravenous immunoglobulin, methylprednisolone, infliximab, and aspirin, which resolved his fever.

Conclusions: This case emphasizes the importance of considering Kawasaki disease as a differential diagnosis in infants with persistent, treatment-resistant fever and abnormal complete blood count findings. Early diagnosis and timely intervention are essential to prevent severe complications, such as coronary artery aneurysms and possible mortality. It underscores the need for heightened awareness and vigilance among healthcare providers in similar clinical scenarios.