Abstract Introduction Necrotizing fasciitis (NF) is a rapidly progressive, life-threatening infection with mortality exceeding 30-40% when diagnosis or debridement is delayed (1). Streptococcus pyogenes (GAS) is a common monomicrobial cause of Type II NF but often lacks gas or abscess on imaging. Reliance on radiographic findings or the Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score can delay surgical intervention (2). We present a case in which the absence of gas and an intermediate LRINEC score masked early recognition of GAS NF. Case Description A 71-year-old woman with type 2 diabetes and obesity presented with three days of progressive right lower extremity pain, swelling, and bruising. She was afebrile with mild leukocytosis; imaging showed soft tissue swelling without gas, and venous Doppler was negative. She was discharged with a presumptive diagnosis of Achilles tendon rupture. Forty-eight hours later, she returned with worsening pain, bullae, and hypotension (BP 84/34 mmHg). Labs revealed marked leukocytosis with 21% bands and an LRINEC score of 5. Repeat CT again showed diffuse edema without gas or abscess. Given the low score and imaging findings, surgery deferred intervention; however, her condition deteriorated rapidly with progressive shock. Blood cultures grew GAS (4/4 bottles). Linezolid and piperacillin-tazobactam were initiated, but she required intubation and vasopressors. She was transferred to a tertiary center, where multiple debridements and free rectus abdominis flap reconstruction were performed. With multidisciplinary care, she achieved full hemodynamic recovery. Discussion This case illustrates that the absence of gas or a low-to-intermediate LRINEC score does not exclude GAS NF. GAS incidence continues to rise (3). Exotoxins SpeA and SpeB cause deep fascial necrosis with minimal gas formation, unlike polymicrobial infections (4). Free air is seen in up to 80% of polymicrobial cases versus 48% of monomicrobial disease (5). The LRINEC score also shows suboptimal diagnostic accuracy (sensitivity 40.8-68.2%) (2). Delay in surgery remains a key determinant of mortality; early exploration within six hours reduces death by about 40% (6). Clinicians must maintain high suspicion despite benign imaging, as prompt surgery and multidisciplinary care are vital for survival. References: 1. Stevens DL, Bryant AE. N Engl J Med. 2017;377:2253-2265. 2. Fernando SM et al. Ann Surg. 2019;269:58-65. 3. Gregory CJ et al. JAMA. 2025;333(17):1498-1507. 4. Matsen FA III et al. AJR Am J Roentgenol. 2015;205:W1-W8. 5. Trauma Surg Acute Care Open. 2021;6:e000745. 6. Nawijn F et al. World J Emerg Surg. 2020;15:4. This abstract is funded by: None
Anand et al. (Fri,) studied this question.
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