Correspondence and reprint requests to:
Dr. Masanori Kawataki
Department of Respiratory Medicine, Ohara Healthcare Foundation,
Kurashiki Central Hospital, 1-1-1 Miwa, Kurashiki, Okayama 710-8602,
Japan
E-mail:masanori19881027@gmail.comKeywords: Necrotizing soft tissue infection, Muscle necrosis
Key clinical message
Necrotizing Soft Tissue Infection can be challenging to differentiate
from abscesses based on computed tomography imaging findings only, so it
is crucial to perform surgical debridement as early as possible.
Case report
A 72-year-old male presented to our hospital with left hip joint pain
and general fatigue for four days. He had a medical history of
erythroderma and was taking prednisolone 5 mg. The examination revealed
pain in the left hip joint during passive movement. Contrast-enhanced
computed tomography (CT) showed low attenuation in the left adductor
muscle group. No fluid retention or increased fat tissue density was
observed (Figure 1). Intramuscular abscess was suspected, and surgical
debridement was performed. Surgical debridement revealed cloudy exudate
in the superficial fascia and synovial sac. The diagnosis of Necrotizing
Soft Tissue Infection (NSTI) was subsequently confirmed.
NSTI on CT show typically gas along the fascia plane, fat stranding,
increased density, edema and thickening of the fascia, obscure
appearance of the fascial surface, non-enhancement of fascia, and fluid
retention. Meanwhile, CT findings of muscle necrosis show low
attenuation and are also associated with muscle
edema1.
In the abscess, fluid attenuation on CT is a collection circumscribed by
an enhanced, irregular, thin wall. Moreover, the surrounding tissue can
develop edema and a low-density area1. Therefore, it
is difficult to distinguish an NSTI from an abscess based on CT imaging
findings alone when the findings are not typical.
Source control improves mortality in NSTI2, and
surgical findings can confirm the diagnosis3.
Conducting a surgical consultation as early as possible is critical if
the imaging findings are not typical. In this case,
Methicillin-resistant Staphylococcus aureus was detected in joint
fluid and tissue cultures. Antibiotic therapy was continued for
approximately 12 weeks, and he was transferred to another hospital for
rehabilitation.
References
- Chang CD, Wu JS. Imaging of Musculoskeletal Soft Tissue Infection.
Semin Roentgenol. 2017;52(1):55-62.
- MartÃnez ML, Ferrer R, Torrents E, et al. Impact of Source Control in
Patients With Severe Sepsis and Septic Shock. Crit Care Med.
2017;45(1):11-19.
- Pelletier J, Gottlieb M, Long B, Perkins JC Jr. Necrotizing Soft
Tissue Infections (NSTI): Pearls and Pitfalls for the Emergency
Clinician. J Emerg Med. 2022;62(4):480-491.
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