RESUMO
BACKGROUND: Benign acute childhood myositis (BACM) is a transient condition mainly affecting children of school age characterized by muscle pain, typically localized to the calf muscle with symmetrical lower extremity pain and difficulty in walking. Usually, the symptomatology is preceded by a viral infection including influenza, parainfluenza, rotavirus, and mycoplasma. METHODS: The case series was conducted in four pediatric hospitals in Catania, Italy, over a 12-year observational period. Clinical examination, laboratory data, course, treatment, and complications of the affected children were extracted from electronic medical records of each hospital. RESULTS: For the case series, 50 children diagnosed with BACM were enrolled: the mean age of affected children was 5.35 years, 86% of were males, and in 56% the affections occurred during the winter. In the affected children, the clinical picture was characterized by previous fever and/or symptoms of inflammation of the upper airways, and followed by pain in the lower extremities up to uncoordinated gait. In 17 cases the etiological agent was isolated, including the influenza virus type B as the most frequent and influenza virus type A, Mycoplasma pneumoniae, beta-hemolytic streptococcus, and herpes simplex virus. Children were treated with supportive therapy. In all the children the muscular symptomatology had a good evolution with progressive marked reduction of pain and of the high level of CKemia. Neither clinical recurrences nor sequelae were reported. CONCLUSION: BACM shows to have in most of the cases a favorable evolution, a spontaneous remission of symptoms, and a good prognosis. However, the disorder generates parental distress for the acute presentation and the striking muscle dysfunction. It is worthy a rapid and early diagnosis to avoid unnecessary diagnostic investigations and a careful follow-up necessary to exclude persistence of symptoms or creatine kinase elevation.