RESUMO
Myositis caused by mumps virus is very rare. Mumps virus has been suggested as a causative agent of inclusion body myositis, but there has been no definite evidence. We experienced a case of severe myositis associated with mumps virus infection. A 21-year old man was admitted because of myalgia, headache, fever, and chill for 2 months. The cerebrospinal fluid analysis performed at a local clinic showed findings compatible with viral meningitis. His blood chemistry results revealed elevated levels of serum creatine kinase, lactate dehydrogenase, and serum myoglobin. On the 5th day of admission, the patient showed pain and swelling of parotid gland and scrotum. Electromyography was compatible with inflammatory myopathy. Muscle biopsy of his calf muscle revealed necrotizing (leukocytoclastic) vasculitis and multifocal myolysis with multinucleation. We suspected mumps virus infection because of his symptoms of meningitis, epididymo-orchitis and parotitis. Mumps virus was isolated in throat culture. The past medical history of the patient's mumps virus vaccination was unclear. After 2 weeks of supportive treatment, the patient's condition was improved.