RESUMEN
AIM: We conducted a prospective study to evaluate the causes and outcome in children with fever of unknown origin (FUO). METHODS: From 1990 to 1999, 185 children with FUO were evaluated. Initial evaluation included routine haematological analysis, Epstein-Barr virus (EBV) serology, urine, stool or blood cultures, chest X-ray and tuberculin probe. RESULTS: In 131 (70%) patients diagnosis was established, and 70 (37.8%) had infectious disease. EBV infection was the most common infection followed by visceral leishmaniasis (VL), urinary tract infection (UTI) and tuberculosis. Autoimmune disorders were diagnosed in 24 (12.9%), Kawasaki disease in 12 (6.4%), malignant diseases in 12 (6.4%) and miscellaneous conditions in 15 (8.1%) patients. In the remaining 54 (30%) patients, diagnosis was not established and most of them had self-limited disease. During the investigation, 26 (14%) patients developed serious organ dysfunction and five patients (two with virus-associated haemophagocytic syndrome, one with VL and two unknown) died. CONCLUSION: The most important infectious causes of FUO in our study were EBV infection and VL. Kawasaki disease represented a significant cause of FUO at the beginning of our study because it was not recognized by primary-care physicians. We report myelodysplastic syndrome as another emerging cause of paediatric FUO. Repeated clinical examination and careful use of specific laboratory examinations, invasive diagnostic procedures or imaging are crucial in approaching paediatric FUO.