Pseudomembranous Colitis: Unveiling an Infrequent Culprit Beyond Clostridium difficile-A Case Report

Area of Science:

• Gastroenterology
• Oncology
• Immunology

Background:

• Immune checkpoint inhibitors (ICIs) are increasingly used for advanced malignancies.
• Immunotherapy-induced pseudomembranous colitis (PMC) is an uncommon but recognized adverse effect of ICIs.
• PMC diagnosis can be challenging due to overlapping features with other colitis types.

Purpose of the Study:

• To present a case of immunotherapy-induced PMC in a patient with gastric adenocarcinoma.
• To highlight the diagnostic difficulties associated with atypical, diffuse colonic involvement in immunotherapy-related colitis.
• To emphasize the need for increased clinical awareness and further research into immunotherapy-induced colitis (IMC).

Main Methods:

• Case report of a 68-year-old male with gastric adenocarcinoma receiving immunotherapy and chemotherapy.
• Exclusion of common etiologies, including Clostridium difficile infection (CDI).
• Diagnostic colonoscopy with biopsy, revealing findings consistent with PMC.
• Treatment with steroid therapy.

Main Results:

• The patient presented with symptoms consistent with PMC, and common causes were ruled out.
• Colonoscopy showed severe mucosal congestion and exudates, indicative of PMC.
• The patient responded well to steroid therapy, with gradual improvement.
• This case illustrates the diagnostic challenges of immunotherapy-induced PMC, especially with diffuse colonic involvement.

Conclusions:

• Immunotherapy-induced PMC requires heightened clinical suspicion, particularly in patients with advanced cancer receiving ICIs.
• The overlapping clinical, endoscopic, and histopathological findings with other colitis forms complicate timely diagnosis.
• Further research is essential to refine diagnostic criteria and management strategies for immunotherapy-induced colitis.