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Abstract

The authors describe four cases of obturator internus muscle (OIM) abscess in children, including their clinical presentations and treatment. This was a retrospective chart review. Children and adolescents younger than 18 years discharged between July 1, 1985, and September 30, 1998, from Brenner Children's Hospital with the diagnosis of muscle abscess or pelvic abscess were identified. A total of 56 patients were identified with the diagnosis of muscle abscess or pelvic abscess. OIM abscess was defined by radiologic findings of an inflammatory process with fluid collection in the OIM, along with the clinical findings suggestive of an OIM abscess. Four of the patients met the definition of OIM muscle abscess. The common presenting features were fever, limp, and hip pain. Computed tomography or magnetic resonance imaging was diagnostic in all four patients, and Staphylococcus aureus was the causative agent in each. All the patients recovered, one after surgical drainage and the other three after antimicrobial therapy alone or with needle aspiration. The presentation of OIM pyomyositis is similar to that of psoas muscle pyomyositis and other infectious processes of the pelvis and hip. The S. aureus is the most common etiologic agent but not the only one reported. Most patients can be managed without open surgical drainage, but needle aspirations may be helpful both therapeutically and diagnostically.

Obturator externus abscess in a 9-year-old child

“…[2,4,11,12,15–25,27,29–31] Methicillin-resistant Staphylococcus aureus (11.5%) [9,11,23,30] or Streptococcus group A (6.5%) [11,28,29] have also been implicated. However, Pannaraj et al [3] report the emergence of methicillin-resistant Staphylococcus aureus in pediatric musculoskeletal infections, especially in the United States, since 2000.…”

“…In 80% of cases, blood cultures are usually sufficient to identify the pathogen. [2,9–12,15–17,19–25,27–30] In cases of negative blood cultures, classical isolation methods yield to pathogen identification in abscess specimens most of the time (22.5%). [4,11,23,25,30,31] …”

Primary obturator internus and obturator externus pyomyositis

“…Pyomyositis is an acute infection of striated muscle that manifests as a localized abscess or an aggressive myonecrotic process [1]. It can be primary or secondary to neighboring or remote infection.…”

“…Primary pyomyositis is a rare condition and usually affects children and adolescents, with a majority of cases involving large skeletal muscles of the lower limbs that may rarely affect the peristatic muscles [2]. It is common in many parts of Africa and the South Pacific; hence, it earned the name tropical pyomyositis [1]. It occurs more frequently in immune compromised patients, or it can be related to factors affecting the muscle itself (strenuous exercise, direct muscle trauma, viral or parasitic myositis) [3,4].…”

“…The most common causative organism (70–90%) is Staphylococcus aureus . Other causative organisms include Streptococcus pyogenes, Neisseria gonorrhoeae, Enterococcus faecalis, Escherichia coli, Salmonella enteritidis and Mycobacterium tuberculosis [1,4,7]. …”