Few studies of pediatric Epstein-Barr virus (EBV)-associated infectious mononucleosis (IM) have been conducted in Korea. We evaluated the clinical features of children with IM to define differences according to age.

We conducted retrospective chart reviews of 68 children aged 0 to 15 years who were diagnosed by EBV-associated IM with EBV-Viral Capsid Antigen(VCA) IgM at laboratory test and were admitted between 2010 and 2014. The children were classified into four age groups: aged 0–3, 4–6, 7–9, and 10–15 years.

The age distribution of patients was as follows: 19 (27.9%) 0–3, 25 (36.8%) 4–6, 13 (19.1%) 7–9, and 11 (16.2%) 10–15. Fever was the most common presentation regardless of age. It was more common in the 0–3 group than the 4–6 group (P = 0.018). Pharyngitis was more common in the 7–9 group than the 0–3 group (P = 0.048), and myalgia was more common in the 10–15 group than the 0–3 group (P = 0.007). Pharyngitis was accompanied by lymphadenopathy, protracted fever, and rash. In the 0–3 age group, the prevalence of rash was higher while the percentage of atypical lymphocytes was lower, but there was no statistical support for this tendency. There were no differences in the frequency of hepatosplenomegaly or laboratory findings between age groups.

IM is not uncommon in young children and its clinical presentation varies with age. Therefore, IM should be suspected in young febrile children with pharyngitis and rash despite low percentages of atypical lymphocytes.