Fever of Unknown Origin Among Children in Two Private, Urban, Tertiary Hospitals: A 27-year Retrospective Study

Introduction: Fever of unknown origin (FUO) is a problem commonly encountered by infectious disease specialists, and even general pediatricians, in spite of the improvement in diagnostic modalities. There is no local study on childhood FUO from a private hospital. Thus, there is a need to determine the etiology of FUO seen in private practice, which may be different from those encountered in government or teaching hospitals. Objectives: The purpose of this study is to identify the etiologies of childhood FUO from two private, urban, tertiary hospitals, as evaluated by a single pediatric infectious disease physician; and to discuss epidemiologic, clinical and diagnostic clues for the most common etiologies. Methods: Childhood FUO cases were compiled from 1993 to 2020. Each consecutive, inpatient, admission or referral of a patient, 18 years or younger, was logged into a personal computer, and the discharge diagnosis for the FUO was recorded. Clinical, epidemiologic, diagnostic and therapeutic data, relevant to the FUO diagnosis were likewise recorded. FUO was defined as daily fever of 380C for ten consecutive days, or more, with no etiology identified after being admitted for seven days. Results: Of 171 cases of childhood FUO, the etiology was an infection in 68%, collagen-vascular disease in 13%, miscellaneous cause in 8%, malignancy in 6%, and no diagnosis in 5%. The most common infections were Epstein Barr Virus (EBV) mononucleosis, tuberculosis, enteric fever, sinusitis, pneumonia and incomplete Kawasaki disease. The most common collagen vascular diseases were juvenile idiopathic arthritis and systemic lupus erythematosus. Hemophagocytic lymphohistiocytosis was the most common miscellaneous cause. Lymphoma was the most common malignancy. Conclusion: This study found EBV mononucleosis, sinusitis, pneumonia, incomplete Kawasaki disease, lymphoma, HLH and Kikuchi-Fujimoto disease to be FUO etiologies not reported previously in other local reports.