Case report: necrotizing fasciitis with ascending mediastinal emphysema secondary to anastomotic perforation after stapled hemorrhoidopexy

Introduction Necrotizing fasciitis (NF) is a life-threatening soft-tissue infection that progresses rapidly, most commonly secondary to surgery or trauma. Stapled hemorrhoidopexy (Procedure for Prolapse and Hemorrhoids, PPH) is a minimally invasive procedure for mixed hemorrhoids; however, anastomotic leakage resulting from a staple-line defect and plausibly related to staple tension or impaired local perfusion can rarely induce enterogenic NF, with ascending mediastinal emphysema being uncommon as a co-presentation with surgically confirmed NF. Case presentation A 37-year-old previously healthy male developed severe perianal pain and a high fever (39.3 °C) on postoperative day 2 after PPH, followed by subcutaneous crepitus with clinical deterioration on postoperative day 3, which prompted transfer to our hospital. CT showed widespread gas spreading from the perianal and ischiorectal fossae through the pelvic and retroperitoneal fascia to the posterior mediastinum and cervical fascial spaces, demonstrating gas tracking along necrotizing fasciitis of the perianal, perineal, ischiorectal, pelvic, and retroperitoneal compartments—subsequently confirmed at surgery—together with radiologically demonstrated ascending mediastinal emphysema; no mediastinal collection or abscess was seen. Emergency transverse colostomy, extensive fascial debridement, broad-spectrum antibiotic therapy, and supportive care were performed. The patient recovered fully, with no recurrence at the 1-year follow-up. Discussion This case highlights the unique fascial plane of spread of the infection and demonstrates a continuous anatomic progression pathway as its core finding: a small posterior post-PPH staple-line defect localized by digital rectal examination and directly measured at surgery, which progresses to rapidly progressive, surgically confirmed perineal, ischiorectal, and retroperitoneal necrotizing fasciitis, with extensive cephalad gas tracking into the posterior mediastinum and cervical spaces (no mediastinal collection) identified on CT. Early CT is pivotal for diagnosing extensive involvement, whereas prompt surgical source control and multidisciplinary collaboration are central to the favorable outcome. The multimodal regimen applied in this case aligns with established principles for necrotizing soft-tissue infections, and the independent contribution of any single intervention cannot be definitively concluded. Conclusion Post-PPH patients with disproportionate pain or crepitus require high clinical suspicion of NF and urgent CT. The present observation adds to the documented anatomic pattern of cephalad gas tracking and underscores the need to distinguish radiologic gas tracking from surgically confirmed necrotizing infection; it does not establish that any particular intervention altered survival.