Clinical Features and Laboratory Findings of Hospitalized Children with Infectious Mononucleosis Caused by Epstein-Barr Virus from Croatia.

The aim of this retrospective 6-year study was to analyze demographic, laboratory and clinical features of 212 patients (<18 years of age) with EBV-associated infectious mononucleosis (IM) hospitalized in a tertiary clinical care center in southeastern Europe and to identify possible predictors of complications. The median patient age was 14.7 years (IQR 7.7-16.5 years), with 59.4% of patients aged between 13 and 18 years. A total of 51.2% of patients were hospitalized within 7 days following the onset of symptoms (median duration of hospitalization was 9 days, IQR 7-11 days). The most common symptoms included fever (97.16%), tonsillitis (87.3%), lymphadenopathy (79.2%), hepatomegaly (77.4%) and splenomegaly (73.1%). Symptom distribution, maximal fever and fever duration did not differ among different age groups. The most common complications included tonsillar hypertrophy, thrombocytopenia, anemia, neutropenia and leukopenia but all patients showed favorable outcomes. Patients who developed three or more complications and those presenting with thrombocytopenia showed significantly longer hospitalization durations. Platelet count, bilirubin, ESR and AST were identified as the most accurate predictors of hospitalization duration using multiple linear regression analysis. Therefore, our results suggest that clinical assessment of individual patients remains the most reliable parameter for patient management and that laboratory findings play only a supporting role.