The human immunodeficiency virus and the enteroviruses occasionally cause myositis. Many other viruses have been rarely reported to cause myositis. The pathogenesis of this entity varies by the virus causing the infection.
The influenza virus may be isolated from muscle tissue on biopsy. For other viruses, the virus may not be found in the muscle tissue, and in those cases, the myositis is felt to be immune- or cytokine-mediated.
Laboratory testing reveals an elevated creatinine kinase level. Treatment is symptomatic.
M60.9 – Myositis, unspecified
240105009 – Viral myositis