Acute pyomyositis of the pelvis: the spectrum of clinical presentations and MR findings.

BACKGROUND

Acute pelvic pyomyositis is uncommon in non-tropical areas.

OBJECTIVE

To summarize the clinical and MR findings in children with acute pelvic pyomyositis.

MATERIALS AND

METHODS

We retrospectively identified 20 children (mean age 9.4 years) who were evaluated by MR and diagnosed with acute pelvis pyomyositis during the time period between January 2002 and June 2005. We reviewed clinical, laboratory, and imaging findings.

RESULTS

Fifteen of the 20 children had secondary pyomyositis associated with osteomyelitis (n=13), septic hip (n=4) or sacroiliitis (n=4); all were previously healthy except for one child with leukemia. Seven of the children with secondary pyomyositis underwent bone scintigraphy; three (43%) did not show pelvic abnormalities. Staphylococcus aureus was cultured in 13 of the 15 (87%) children. Five of the 20 children had primary pyomyositis. Three had underlying disease and two others were engaged in vigorous physical activity. Bone scintigraphies (n=2) were negative. Cultures were positive for S. aureus in three of the five (60%) children.

CONCLUSION

Septic hip should be the first diagnostic consideration in children with fever and acute hip pain. Pyomyositis should be considered if arthrocentesis is negative or there is clinical suspicion of infection outside the hip joint. MR is the preferred imaging modality for evaluating foci of pyomyositis, muscle abscesses, and additional foci of infection within the pelvis.