Necrotizing Fasciitis Extending from the Left Iliopsoas to the Left Thigh Due to Retroperitoneal Penetration of the Descending Colon: A Case Report

Our plain-English summary of Necrotizing Fasciitis Extending from the Left Iliopsoas to the Left Thigh Due to Retroperitoneal Penetration of the Descending Colon: A Case Report, by Y. Matsuo, N. Kawahara, S. Tanizawa, et al (Surgical Case Reports, 2026).

The study

• Authors: Y. Matsuo, N. Kawahara, S. Tanizawa, M. Kojima, K. Morishita
• Journal: Surgical Case Reports
• Published: 2026;12(1)
• Type of article: Case report
• Read it: PubMed · Publisher · Free full text

Abstract

Introduction: Necrotizing fasciitis is a severe soft tissue infection characterized by rapid destruction of the fascia and subcutaneous tissue, with a high mortality rate of 20%-40%. Although trauma and insect bites are common causes, gastrointestinal perforation as an etiology is exceedingly rare.

Case Presentation: We report the case of a 70-year-old man receiving combination immunotherapy with nivolumab and ipilimumab for malignant pleural mesothelioma. The patient had been taking 12.5 mg of prednisolone daily for 6 months to manage immunotherapy-induced adrenal insufficiency and enteritis. He presented with lower abdominal pain and chills and was diagnosed with septic shock upon hospital arrival. CT revealed extensive gas extending from the left abdominal wall to the retroperitoneum and left thigh, confirming necrotizing fasciitis. Emergency surgery revealed feculent fluid near the left iliopsoas muscle, indicating retroperitoneal perforation of the descending colon. The patient underwent a left hemicolectomy and double-barrel ileostomy, followed by multiple surgical debridement and drainage procedures. After infection control, he recovered and was transferred for rehabilitation.

Conclusions: Immunosuppressed patients receiving prolonged steroid therapy may be at a higher risk of developing necrotizing fasciitis due to gastrointestinal perforation. Timely infection control and aggressive surgical management are essential for improving patient outcomes.

© 2026 The Author(s). Published by Japan Surgical Society.

In plain English

This was a case report with a review of previously published cases. It described a 70-year-old man treated with the immunotherapy drugs nivolumab and ipilimumab for malignant pleural mesothelioma, who had taken the steroid prednisolone (12.5 mg daily) for 6 months. The article did not discuss asbestos. The patient arrived at hospital in septic shock. A CT scan showed gas spreading from the left abdominal wall and retroperitoneum to the left thigh muscles, and the diagnosis was necrotizing fasciitis, a severe soft tissue infection. Surgery found inflammation and adhesions consistent with the descending colon having penetrated into the retroperitoneum, and a left hemicolectomy was performed. A leak where the bowel had been rejoined, found 16 days after surgery, required a second operation. The patient was transferred to a rehabilitation facility on day 40. In a literature search, the authors found 34 reported cases of necrotizing fasciitis linked to retroperitoneal perforation or penetration, and at least 12 of those patients (35%) died. The authors concluded that immunotherapy, prolonged steroid therapy or treatment for chronic enteritis may raise the risk of this complication.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: case report with a review of published case reports
• Who was studied: one 70-year-old man receiving nivolumab and ipilimumab for malignant pleural mesothelioma
• Exposure: No asbestos exposure is reported. The treatments discussed were combination immunotherapy (nivolumab and ipilimumab) and prednisolone 12.5 mg daily for 6 months, taken for immunotherapy-related enteritis and adrenal insufficiency.
• Main results:
  • On arrival the patient had a systolic blood pressure of 50 mmHg and was diagnosed with septic shock
  • CT showed extensive gas from the left abdominal wall and retroperitoneum to the left thigh muscles
  • At surgery, the descending colon showed severe inflammation and dense adhesions consistent with retroperitoneal penetration
  • A left hemicolectomy with double-barrel ileostomy was performed
  • A CT scan on postoperative day 16 showed an anastomotic leak. This led to a second operation involving additional resection, drainage and a transverse colostomy.
  • The article refers to the operation for the leak as the 2nd operation
  • Examination of the removed colon showed transmural necrosis with dense neutrophilic infiltration at the perforation site. No specific pathological cause of the perforation (no malignancy or diverticular disease) was found.
  • The patient was transferred to a rehabilitation facility on postoperative day 40
  • The authors' PubMed search found 34 previously reported cases. At least 12 of those patients (35%) died of septic multi-organ failure, and a history of steroid use was reported in 2 cases (6%).
  • The authors suggested that immunosuppression from immunotherapy and steroid use may have contributed to bowel wall fragility in this patient
• The authors' conclusion: The authors concluded that patients receiving immunotherapy, prolonged steroid therapy, or treatment for chronic enteritis may have an increased risk of gastrointestinal wall compromise, predisposing them to retroperitoneal perforation and necrotizing fasciitis. They added that such cases require early recognition, prompt source control and aggressive surgery.

Topics

Medical terms in this study, explained in our Lexicon: Etiology, Immunotherapy, Nivolumab (Opdivo), Ipilimumab (Yervoy), Pleural Mesothelioma, Retroperitoneum.

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