Fever of Unknown Origin in Young Children: Think Kawasaki

Background: Kawasaki disease (KD), a vasculitis of unknown etiology, is an important cause of prolonged fever in childhood. Fever lasting more than five days and at least four signs of mucocutaneous inflammation characterize it. It’s main complication are coronary artery aneurysms being the primary cause of acquired heart disease in children in developed countries.

Case-report: A 22-month-old girl is admitted to our hospital with a persistent fever for eight days accompanied by a generalized maculo-papular exanthema that affected palms, to which bilateral cervical adenopathies are associated at the sixth day of disease. The serial investigational tests performed revealed leukocytosis with neutrophilia and a reactive-C protein maximum 26,5 mg/dL and she was medicated with amoxicillin for the suspicion of an occult bacteremia, without improvement. At admission she fulfilled three clinical criteria for KD and the remainder laboratory results supported the diagnosis: a normocytic normochromic anemia (minimum of 7,4 g/dL) and hypoalbuminemia (minimum of 2,8 g/dL). The urinary exam, chest radiography and blood cultures were negative. An echocardiogram was performed revealing a dilation of the anterior descendent coronary artery (Z-score +2,35). She was administered intravenous immunoglobulin (IVIG) in a single dose of 2g/kg and initiated aspirin in an anti-inflammatory dosage. After the initial clinical improvement the fever reappeared in two days. She repeated the administration of IVIG without improvement. At the tenth day of hospitalization she initiated methylprednisolone pulses for three days, with resolution of the fever and progressive clinical improvement. She was discharged with an overlapping echocardiographic assessment and antiplatelet dosage aspirin.

Conclusion: The diagnosis of incomplete KD may be a clinical challenge especially in the first 24 months of life. With this report we aim to alert to the differential diagnosis of a child with fever of unknown origin and the importance of the echocardiographic assessment in the diagnostic evaluation.