35 yo female patient with history of IVDA presented with upper medial arm pain. She had recently had an I&D of a small left forearm abscess but now complained of severe pain and mild erythema of upper arm. On exam, her upper arm was tender, mildly erythematous, and indurated. EMBU showed findings concerning for what diagnosis?

The ultrasound shows cobblestoning and several pockets of subcutaneous air concerning for necrotizing fasciitis. CT scan confirmed the presence of subcutaneous air in the tissue. Surgery was consulted and took the patient to OR immediately for exploration and debridement.

The classic ultrasound finding of necrotizing fasciitis is air/gas in the subcutaneous tissue that appears as small echogenic foci (small bright white lines or spots) with posterior "dirty shadowing" (with an appearance similar to the shadowing behind the pleural lines on a lung ultrasound). You may also see fascial and subcutaneous tissue thickening or fluid accumulations in the deeper fascial levels. Utilize ultrasound early for evaluation of soft tissue infections - presence of subcutaneous air should prompt emergent surgery consultation.

-Allison Zanaboni, MD, Emergency Medicine Ultrasound Fellow

References

1. Yen, Zui‐Shen, et al. "Ultrasonographic Screening of Clinically‐suspected Necrotizing Fasciitis." Academic emergency medicine 9.12 (2002): 1448-1451.

2. Castleberg, E. (2014). Diagnosis of necrotizing fasciitis with bedside ultrasound: The STAFF exam. The Western Journal of Emergency Medicine., 15, 111-113.

3. Oelze, L. (2013). Emergency ultrasonography for the early diagnosis of necrotizing fasciitis: A case series from the ED. The American Journal of Emergency Medicine., 31, 632.e5-632.e7.

4. Tsai, Chih-Cheng, et al. "Early diagnosis of necrotizing fasciitis by utilization of ultrasonography." The Kaohsiung journal of medical sciences 12.4 (1996): 235-240.

5. Shyy, William ; Knight, Roneesha S. ; Goldstein, Ruth ; Isaacs, Eric D. ; Teismann, Nathan A. Journal of Ultrasound in Medicine, October 2016, Vol.35(10), pp.2273-2277

6.Wronski, M. (2011). Necrotizing fasciitis: Early sonographic diagnosis. Journal of Clinical Ultrasound., 39, 236-239.