Abstract
Ipilimumab and nivolumab are immune checkpoint inhibitors that have recently been used in the treatment of metastatic melanoma and other cancers. Immune-mediated colitis is one of their adverse events that need to be differentiated from low-grade diarrhea as one of the most common side effects. A 51-year-old woman with relapsed metastatic melanoma presented with intractable diarrhea, nausea, vomiting, and generalized abdominal pain. The patient had been treated with ipilimumab and nivolumab in the past two months. The infectious workup was inconclusive. Colonoscopy demonstrated severe colitis, and biopsies were consistent with colitis. Combination chemotherapy was stopped. The patient was treated with intravenous and oral steroids, and her symptoms improved. A combination of ipilimumab and nivolumab increases the chance of immune-mediated colitis, and steroids should be started promptly to avoid complications such as bowel perforation and toxic megacolon.