Pneumococcal pyomyositis: A patient with diagnostic problems and complications

Pyomyositis is an uncommon condition that may present a difficult problem i n diagnosis. We report the development of Streptococcus pneumoniae pyomyosi tis involving the iliacus, iliopsoas, and gluteus muscles in a patient with elevated serum levels of antinuclear and antiphospholipid antibodies but w ithout clinical evidence of connective tissue disease. Magnetic resonance i maging demonstrated rapid evolution of the infection, with progression from muscle edema to abscess formation over a period of 10 days. The diagnosis was initially missed, and osteomyelitis and sacroiliitis developed. Pyomyos itis should be suspected in patients with the acute onset of severe, locali zed muscle pain and fever. As in this case, failure to promptly diagnose an d treat this infection can result in significant morbidity.