Febre de etiologia indeterminada: encruzilhada de diagnósticos

background: the most common causes of fever of unknown origin are infectious diseases, rheumatologic or immunologic diseases, and malignancies. case report: the case of a four years old male child with fever, neck pain and limping gait is presented. he was anemic and had elevated inflammatory markers. he developed gradual pallor, maculopapular rash appearing with fever peaks, and cervical lymphadenopathy. echocardiographic documentation of coronary artery ectasia, lead to intravenous immunoglobulin (ivig) therapy for suspected atypical kawasaki disease (akd). the most probable diagnosis of systemic-onset juvenile idiopathic arthritis (sjia) was made after fever maintenance. discussion: it is difficult to differentiate between akd and sjia because there are no specific findings. the suspicion of akd should lead to ivig therapy, but failure to respond is not an exclusion criterion (10% of patients are refractory cases). systemic inflammatory disorders, like sjia, may be associated with coronary artery dilation. this finding supports a diagnosis of akd but is not specific for the condition.