Clinical characteristics in hospitalized children with infectious mononucleosis in Shanghai China: a single-center retrospective study

To investigate clinical features and peripheral blood inflammatory markers in children with Epstein-Barr virus (EBV)-induced infectious mononucleosis (IM), analyze their correlation with disease severity, enable early identification of severe cases, and provide a theoretical basis for early clinical intervention. A retrospective analysis was performed on 156 hospitalized children with EBV-related IM (January 2019-December 2024). EBV nucleic acid was detected via real-time PCR. Patients were grouped by blood EBV-DNA load (positive/negative). Demographics, clinical manifestations, laboratory findings, and liver/spleen/lymph node imaging were collected and analyzed. Among 156 pediatric IM patients (mean age 7 years), IM occurred predominantly in spring (28.20%) and autumn (28.21%), with children aged ≥ 7 years identified as the high-risk group. EBV-DNA positivity was higher in summer and winter. EBV-DNA positivity correlated with disease severity, as evidenced by longer hospitalization (9 vs. 7 days, P = 0.038), elevated inflammatory markers (LDH, ALT, AST), coagulation abnormalities (D-dimer; P < 0.05), and altered immune profiles (elevated CD3+CD8+ T cells and reduced NK cells; P < 0.05). Receiver operating characteristic (ROC) analysis identified CD3+ T cells (AUC = 0.664) and D-dimer (AUC = 0.692) as primary predictors biomarkers for IM, with CD8+ T cells, LDH, and ALT as supportive biomarkers. Biomarker combination boosted predictive accuracy (AUC = 0.713, 72.1% sensitivity, 62% specificity), demonstrating key synergistic diagnostic value in EBV pathogenesis. EBV infection is prevalent among school-aged children in Shanghai, causing significant cellular and humoral immune dysfunction. Longitudinal monitoring of immunological parameters is crucial. EBV-DNA load is a valuable prognostic biomarker for severe IM; elevated inflammatory markers and immune dysregulation in EBV-DNA-positive children are critical for severity assessment.