Benign acute childhood myositis.

Four school children, aged 6 to 9 years, had acute postinfectious myositis. The prodromal illness usually involved the upper respiratory tract, but gastrointestinal symptoms were also seen. Fever and nonspecific malaise were characteristic. After cessation of the illness, myalgia involved the calves and thighs. Arm and neck muscles were less frequently affected. Weakness was less marked than muscle pain. Serum creatine phosphokinase (CPK) was markedly increased in all cases. Myalgia and CPK levels subsided in less than a week, although one child was not back to normal for 4 weeks. Two children had electromyography, and patchy myopathic changes were found. Viral studies were not helpful in any of the cases.