RESUMO
Pyomyositis is a term used to denote primary pyogenic infection of a skeletal muscle. It is a rare disease that was first described in immunodeficient patients living in tropical climates. Lately, however, cases involving healthy children have been described in temperate climates. The origin of primary pyomyositis remains unclear, although it is thought to be caused by seeding from transient bacteremia. Onset of disease is insidious, therefore necessitating rapid diagnosis to successfully select appropriate antibiotic therapy and avoid complications. The signs and symptoms of pyomyositis are nonspecific, which highlights the importance of maintaining a broad differential diagnosis including disease entities such as osteomyelitis and septic arthritis. Magnetic resonance imaging is considered the best imaging modality for distinguishing pyomyositis from other potential etiologies. Here, we present two cases of primary pyomyositis of the lower limb muscles in an 8-year-old boy and in an 11-year-old girl.