Clinical Features and Laboratory Findings in Children Diagnosed with Benign Acute Childhood Myositis (BACM)

Abstract

Purpose: This study was performed to review the relationship between the clinical features and laboratory findings of patients suspected of benign acute childhood myositis (BACM) in children and adolescents with bilateral calf pain and gait disturbances. Methods: From January 1, 2010 to December 31, 2016, the clinical and laboratory findings of patients who visited Dongguk University Ilsan Hospital with the sudden onset fever and muscle pain were retrospectively examined. Results: The total number of patients was 29 (21 males and 8 females), and their mean age was 5.5 years. The mean duration of fever was 4.2 days. The mean duration from the onset of fever to show the symptom was 3.2 days. The mean recovery period from myositis was 2.4 days. The mean duration of hospitalization was 2.2 days. Fever and bilateral calf pain were the most common symptoms; however, cough, rhinorrhea, sore throat, headache, and abdominal pain were also observed. The causative agent of BACM was influenza B infection in 23 (79.3%) of the cases. Creatinine phosphokinase (CPK), myoglobin, aspartate aminotransferase (AST), and alanine transaminase (ALT) values were higher in the shorter duration of fever and were statistically significant. The following values were noted: CPK (r=- 0.472), myoglobin (r=-0.472), AST (r=-0.443), and ALT (r=-0.459). The longer the pain period, the lower the white blood cell (WBC) count (r=-0.655). Conclusion: BACM is mostly associated with the influenza B virus. Time to onset of symptoms after fever and WBC levels are related to muscle enzyme levels and duration of symptoms in BACM.