CASE 14345 Published on 23.01.2017

Gas within the bone: Emphysematous Osteomyelitis

Section

Musculoskeletal system

Case Type

Clinical Cases

Authors

Dayananda Sagar G, Rajesh Lavakumar, Sunita Gopalan, Vidhya Rani R

Department of Radiology, Columbia Asia Referral Hospital, Bengaluru, India 560055 Email:dayananda.s@columbiaasia.com
Patient

66 years, female

Categories
Area of Interest Musculoskeletal system, Musculoskeletal soft tissue ; Imaging Technique CT
Clinical History
A female patient with type II diabetes and chronic kidney disease presented with complaints of fever and altered sensorium. Plain-CT performed for suspected urosepsis demonstrated an incidental finding. She continued to deteriorate during the hospital stay. Blood cultures revealed E-coli. She was discharged against medical advice and was lost for follow up.
Imaging Findings
Plain CT demonstrated multiple pockets of gas within the right pubic bone, pubic symphysis and adjacent Pectineus muscle. Imaging findings were consistent with emphysematous osteomyelitis of the right pubic bone
Discussion
Presence of intraosseous air in the absence of direct contact between bone and air such as compound fracture or recent surgery is pathognomonic of emphysematous osteomyelitis [1, 2].
Ram et al. first described intraosseous gas as a new sign of osteomyelitis in 1981 [3]. About 25 cases of emphysematous osteomyelitis are documented in literature until 2012, [4] followed by few case reports to date. It is a rare form of osteomyelitis, potentially life threatening, the early diagnosis of which is of paramount importance in patient management.
Luey and colleagues, in their extensive review of 25 case reports have documented that the median age of presentation was 51 years with no sex predilection [4]. Underlying co-morbidity such as diabetes or malignancy is a strong predisposing factor. Majority of infections are acquired through haematogenous route [4]. However, few cases of emphysematous osteomyelitis following spread from intra-abdominal source, abdominal or spinal surgery, or from soft tissue infections are also documented [4, 5]. The infection can be either monomicrobial or polymicrobial, with the most commonly isolated organism being either an anaerobe or a member of the enterobacteriaceae family [4].
Radiologically emphysematous osteomyelitis is characterized by the presence of locules of gas within bone and adjacent soft tissues. In advanced cases, intraosseous or soft tissue abscesses may be found. Such findings may be difficult to detect on plain radiographs, especially in earlier stages. CT is excellent in detection of early signs of infection such as gas, with MRI adding the benefit of better depiction of marrow signal abnormalities and soft tissue changes.
The important radiological differential is vacuum phenomenon seen in degenerative conditions of the spine, less commonly with osteonecrosis, vertebral collapse or malignancy. This differentiation is crucial because vertebral involvement in emphysematous osteomyelitis is most common, followed by pelvis and lower extremity bones [4]. Feng et al. have described some of the features that differentiates vacuum phenomenon from infective gas in the spine [6]. The distribution of gas is linear, well demarcated, band-like or triangular in non-infective conditions whereas in infective conditions the distribution of gas is uneven, bubbly with extension into adjacent soft tissue [6]. On the other hand, presence of intraosseous gas in appendicular skeleton is pathognomonic of emphysematous osteomyelitis.
Emphysematous osteomyelitis is associated with significant morbidity and mortality especially in diabetic patients. The presence of intraosseous gas is an alarming sign that the reporting radiologist must recognize to institute timely surgical or antimicrobial therapy.
Differential Diagnosis List
Emphysematous osteomyelitis of right pubic bone
1. Vacuum phenomenon
2. Intraosseous pneumocysts
3. Osteonecrosis
Final Diagnosis
Emphysematous osteomyelitis of right pubic bone
Case information
URL: https://www.eurorad.org/case/14345
DOI: 10.1594/EURORAD/CASE.14345
ISSN: 1563-4086
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