Review of Children Diagnosed with Acute Myositis of Calves Admitted to a Regional Hospital in Hong Kong in the Period 2003-2012 CO SHAM, K TSE

Objective: To investigate the clinical features, management and outcome of all children admitted to a regional hospital in Hong Kong from 2003 to 2012 because of benign acute childhood myositis. Method: A retrospective study was conducted in a regional hospital. Hospital records of children admitted from year 2003 to 2012 with diagnostic coding of myositis, rhabdomyolysis and myalgia were reviewed. Those presented with acute onset of pain in the calves, preceded by a febrile episode, and with raised serum creatine kinase level were included. Data including gender, age, causative agent and outcome were analysed. Those with myositis of calves associated with influenza were compared with a comparative sample of influenza A and influenza B patients obtained randomly from the electronic medical record system. The age, sex and length of hospitalisation of this group of patients were compared with all patients with influenza admitted in the study period. Results: Seventy-one cases fulfilled our search criteria. Thirty-five cases were excluded for various reasons and the remaining cases were evaluated. The median age at presentation was 6-year-old and 75% of the affected patients were boys. The median length of hospitalisation was 3 days. Sixty percent of the cases were associated with influenza B virus. All patients well recovered with no mortality. The level of serum creatine kinase level at presentation did not correlate with length of stay in hospital. There was no statistically significant difference in length of hospital stay between the 24 cases of influenza associated acute myositis of calves and the 24 randomly selected cases of influenza without myositis for comparison. Conclusions: Patients with benign acute childhood myositis carried good prognosis. Unnecessary diagnostic investigations could be avoided with careful history and physical examination.