Case Report: Immune checkpoint inhibitor-induced gastrointestinal toxicity: the diagnostic challenge of sequential ileus and colitis

The article describes a case of a patient with metastatic esophageal mucosal melanoma who developed sequential gastrointestinal complications following treatment with combination ipilimumab and nivolumab (immune checkpoint inhibitors). The patient initially developed intractable nausea, vomiting, and constipation, with CT imaging demonstrating small bowel dilatation without a mechanical obstruction point, suggesting immune-mediated ileus. Despite intravenous corticosteroid treatment, the clinical presentation evolved into high-frequency diarrhea with signs of enterocolitis. Initial response to prolonged corticosteroid therapy was followed by recurrent diarrhea, which ultimately improved after infliximab treatment. The case emphasizes that intestinal pseudo-obstruction is an important but often overlooked immune-related adverse event and that gastrointestinal dysmotility may precede, coexist with, or be masked by more familiar immune-mediated colitis.