A total of 126 children were enrolled; 60 were girls and 66 were boys. The mean age was 6.7 years old. Infection accounted for 27.0% of cases, followed by undiagnosed cases (23.8%), miscellaneous etiologies (19.8%), malignancies (16.6%), and autoimmune disorders (12.7%). Epstein-Barr virus (EBV) and cytomegalovirus (CMV) were the most commonly found pathogens for infectious disease, and Kawasaki disease (KD) was the top cause of miscellaneous diagnosis.