Myositis during acute viral infections, also known as acute benign myositis of childhood (MBAI), is a clinical picture well described in the literature. Influenza virus (A and B) is one of the most common viral etiologies. The diagnosis is clinical, based on symptoms such as lower extremity pain with limitation of walking, and is combined with laboratory data such as elevation of blood creatine kinase (CK). Identifying patients who develop a myositis picture in the course of influenza infection is important not only for proper management of those, albeit rare, cases that may go on to complications, but also because of the need to reassure the family about the almost certainly benign evolution of the condition. During the 2023-2024 winter season, the association between influenza virus infection and myositis appeared particularly frequent; here we describe its clinical aspects and main pathogenetic hypotheses.
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