Small-Bowel Capsule Endoscopy in Immune-Mediated Enterocolitis: A Case Series of Four Patients

Immune checkpoint inhibitors (ICIs) have emerged as a cornerstone of cancer immunotherapy but are associated with immune-mediated adverse events (imAEs), including gastrointestinal toxicities. Among these, enteritis is a less common but clinically significant complication. However, small intestinal involvement remains under-recognized, and endoscopic findings are not well characterized. We report four cases of imAE enteritis in which small-bowel capsule endoscopy (SBCE) was performed. SBCE revealed variable mucosal abnormalities, including villous atrophy, aphthous ulcers, and extensive erosions; in one case, deep circumferential ulcers with stricture were observed. While one patient responded to corticosteroids, the other three required escalation to biologic therapy due to steroid-refractory disease. These findings suggest that SBCE may play a valuable role in assessing disease extent and predicting treatment responsiveness in imAE enteritis. Early utilization of SBCE could facilitate timely therapeutic decision-making in affected patients.