Pyomyositis in a temperate climate is a rare condition in children according the number of reports. Most authors postulate trauma with simultaneous bacteriemia is the most likely mechanism.

We reviewed 8 cases, 4 boys and 4 girls. Their mean age was 9,2 y. ( 5 to 16 y.). Pain, tenderness, limp and fever were the most common signs. Duration of symptoms before initial evaluation was 8,1 d. (5 to 15 d.). 6 patients had fever (> 38,5°C), all had leukocytosis and a shift to the left in the WBC, and a elevated ESR 69,3 mm/h(32 to110), as well as an increased C-protein reactive (mean=10). All cases had radiographs, US in 6, CT scan in 6 and MRI in 5. These studies demonstrated involvement of psoas muscle in 4, obturator internus and externus in 3, and gluteal and quadratus femoris in 1. We found simultaneous involvement of ischiopubic ramus in 3, one iliac osteomyelitis, one piogenic sacro-ileitis, one supurative lymphadenitis and one resection for Crohn’s disease. Incision and drainage of muscular abcess (5 cases)plus IV antibiotics(8 cases) provided uneventfully resolution. 4 cultures were positive to Staf Aureus, 1 to E. Coli and 3 negatives.

In this series we found 87% of pelvic pyomyositis with simultaneous septic factors. We consider them more causative factors than predisponing, and pyomyositis as a secondary entity. Previous reports propose pyomyo-sitis as a primary condition after a speculative bacter-aemia with a muscle strain, as the likeliest cause. MRI could be helpful to determine bone involvement or other regional problems in pelvic pyomyositis.