Fulminant truncal necrotizing fasciitis of perianal origin with mediastinal extension: a case report

Necrotizing fasciitis (NF) is a rare but life-threatening soft-tissue infection characterized by rapidly progressive necrosis of the fascia and subcutaneous tissue. Early manifestations are often nonspecific, and delayed diagnosis is associated with substantial mortality. Early recognition and immediate intervention are critical to improving outcomes.

A 34-year-old man presented with progressive left lower abdominal pain and persistent perianal discomfort 5 days after radical drainage of a perianal abscess combined with internal hemorrhoid ligation. Despite initial treatment with antibiotics, glycemic control, and fluid resuscitation, his condition continued to deteriorate, and he was subsequently transferred to our hospital for definitive treatment. Emergency debridement demonstrated extensive spread of infection from the ischiorectal fossa through the obturator and abdominal fascial planes to the contralateral gluteal region and mediastinal/para-mediastinal fascial planes. Microbiological cultures confirmed type I polymicrobial infection involving Escherichia coli, Enterococcus raffinosus, and Candida albicans. Postoperatively, the patient developed early hypoxemic respiratory failure requiring invasive mechanical ventilation. The lowest documented PaO₂/FiO₂ ratio was 98.6 mmHg, and oxygenation improved after ventilatory optimization, increased PEEP, fluid restriction, and diuretic therapy. He was successfully extubated on postoperative day 3 and subsequently transitioned to high-flow nasal oxygen. Following combined anti-infective therapy, organ support, and nutritional management, the patient recovered and was discharged.

NF can affect any body region, with the perineum, lower limbs, and postoperative wounds being most common. The disease can rapidly progress to systemic infection, sepsis, and multiple organ dysfunction syndrome. Early diagnosis, urgent surgical intervention, and multidisciplinary management are crucial for favorable outcomes.