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

Abstract

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.

Benign acute childhood myositis: an alarming condition with an excellent prognosis!

“…Most commonly occur after influenza B and occasionally influenza A infection, but parainfluenza, adenovirus, herpes simplex, Epstein-Barr, Coxsackie, rotavirus, and M pneumoniae have also been implicated [1][2][3][5][6][7][8][9][10], as found in our study. As evidenced, key elements in the diagnosis are a preceding upper respiratory infection followed by the acute onset of typical myositis clinical findings, predominantly affecting gastrocnemius-soleus muscles.…”

“…Benign acute childhood myositis is a rare disorder and continues to lead physicians into unnecessary workup when they are unfamiliar with its presentation [1][2][3][4][5]. Most commonly occur after influenza B and occasionally influenza A infection, but parainfluenza, adenovirus, herpes simplex, Epstein-Barr, Coxsackie, rotavirus, and M pneumoniae have also been implicated [1][2][3][5][6][7][8][9][10], as found in our study.…”

“…Transient hematological abnormalities (mild leukopenia, neutropenia, and thrombocytopenia) are also seen [1,3,[8][9][10]. Erythrocyte sedimentation rate and CRP are usually normal but may be mildly elevated [1][2][3]5,6]. Patients with this typical clinical presentation can be treated as an outpatient [1,5].…”

“…As evidenced, key elements in the diagnosis are a preceding upper respiratory infection followed by the acute onset of typical myositis clinical findings, predominantly affecting gastrocnemius-soleus muscles. Further clinical features include school-aged boys and late winter-early spring predominance, elevated CK, and aminotransferase levels (especially AST) [1][2][3][4][5][6][7][8][9][10]. Transient hematological abnormalities (mild leukopenia, neutropenia, and thrombocytopenia) are also seen [1,3,[8][9][10].…”

“…Further clinical features include school-aged boys and late winter-early spring predominance, elevated CK, and aminotransferase levels (especially AST) [1][2][3][4][5][6][7][8][9][10]. Transient hematological abnormalities (mild leukopenia, neutropenia, and thrombocytopenia) are also seen [1,3,[8][9][10]. Erythrocyte sedimentation rate and CRP are usually normal but may be mildly elevated [1][2][3]5,6].…”