Flexible Sigmoidoscopy Rather than Colonoscopy Is Adequate for the Diagnosis of Ipilimumab-Associated Colitis.

Objectives: Treatment with ipilimumab, a cytotoxic T lymphocyte antigen-4 approved for metastatic melanoma can result in clinically significant immune-mediated drug injury in the form of colitis. Timely diagnosis and response are essential for optimal management. The aims of our study were to determine the percentage of our patients with ipilimumab-associated colitis in which the colitis could be diagnosed by flexible sigmoidoscopy only and to describe the variations in endoscopic and histologic findings as well as the patients' clinical courses. Methods: We retrospectively reviewed 244 patients with metastatic melanoma, treated them with ipilimumab, and characterized the endoscopic and histologic features for those who developed colitis. Results: Of the 68 patients who presented with diarrhea, 33 were diagnosed as having ipilimumab-associated colitis. Endoscopically, all of them had involvement of the left side of the colon; none of the patients were noted to have isolated right colon involvement. Conclusions: Ipilimumab-associated colitis can be diagnosed with a flexible sigmoidoscopy alone, obviating the need for full colonoscopy.