A case of benign acute childhood myositis associated with influenza A (H1N1) virus infection.

Benign acute childhood myositis (BACM) is a rare transient condition usually occurring at the early convalescent phase of a viral upper respiratory tract illness, normally influenza A, and, more frequently, influenza B infection. It is characterized by acute-onset difficulty in walking as a result of severe bilateral calf pain and by elevated muscle enzymes including creatinine kinase. It is self-limiting because there is rapid full recovery usually within 1 week. We describe the first case of BACM in association with the new pandemic influenza A (H1N1) virus infection in an 11-year-old boy from Cyprus. The child had the typical clinical and laboratory characteristics of this clinical syndrome. Prompt diagnosis of this clinical entity is essential to prevent unnecessary investigations and therapeutic interventions and to reassure the patient and parents of the excellent prognosis.