Influenza-Associated Benign Acute Childhood Myositis During the 2024–2025 Season

Background : The aim of this study was to describe the clinical and laboratory characteristics of hospitalized pediatric influenza cases during the 2024-2025 season in Northwestern Greece, with a focus on influenza-associated benign acute childhood myositis (BACM). Methods : We conducted a retrospective observational study of children aged 0-16 years hospitalized with laboratory-confirmed influenza between October 2024 and May 2025 at two pediatric departments. BACM was diagnosed based on calf pain, difficulty walking, elevated creatine kinase (CK), and symptom resolution without other causes. Results : A total of 113 children (mean age 7.0 ± 4.2 years; 50.4% male) were included; 61.1% had influenza A and 38.9% influenza B. None had received influenza vaccination. BACM was identified in 37 children (32.7%), who were significantly older than patients without myositis (9.3 ± 2.7 vs. 6.0 ± 4.5 years, p 2 (1) = 22.7, p Conclusions : In our hospitalized cohort, BACM was observed relatively frequently (32.7%), particularly in children with influenza B; however, this proportion reflects hospitalized cases and does not indicate the true incidence in the general pediatric population. Despite high CK levels, outcomes were favorable with supportive care. These findings underscore the importance of clinician awareness to avoid unnecessary investigations and hospitalizations

Creatine kinase · Incidence (geometry · Multicenter study · Myopathy · Myositis · Observational study · Pediatric intensive care unit · Retrospective cohort study · Rhabdomyolysis · Inflammatory Myopathies and Dermatomyositis · Muscle and Compartmental Disorders