Primary pyomyositis of the forearm in a non-immunocompromised boy

Abstract

We present a previously healthy 5-year-old boy with primary pyomyositis of the right forearm due to methicillin-susceptible Staphylococcus aureus. He had no apparent portal of entry. He was cured after surgical drainage of the affected forearm along with a three-week course of sequential intravenous and oral antibiotics. Pyomyositis is a rare but serious bacterial infection of striated muscle that should be part of the differential diagnosis of any child with fever, localized extremity pain, and edema. It can advance to abscess formation in the affected muscle and have serious short- and long-term consequences. The vast majority of cases in both tropical and temperate regions are caused by S. aureus. Hence, empirical anti-staphylococcal therapy pending culture results is appropriate. MRI is the best imaging modality for diagnosis, while common laboratory tests like hemogram, ESR and CRP are useful for monitoring response to therapy. Early diagnosis, surgical drainage and lengthy treatment with appropriate antibiotics lead to clinical cure in most cases.