Paediatric Myositis Linked to Influenza B Infection: A Case Report

Objective: To report a rare case of myositis associated with Influenza B infection in a pediatric patient, emphasizing the clinical presentation, diagnostic challenges, and management strategies. Case: We present the case of a 9-year-old male who developed acute myositis following an Influenza B infection, characterized by severe muscle pain, difficulty walking, and an exceptionally high Creatine Phosphokinase (CPK) level of 33,256 U/L. Despite initial negative results for Influenza B, subsequent testing confirmed the infection, leading to a prompt and successful treatment with intravenous hydration and oseltamivir. Conclusion: Myositis associated with Influenza B, although rare, should be considered in pediatric patients presenting with sudden muscle pain and gait disturbances, particularly during influenza season. Early diagnosis and intervention are crucial in preventing complications such as rhabdomyolysis and acute renal failure.