Diffuse Metastatic Melanoma in the GI Lumen Following Immune Checkpoint Inhibitor Colitis Treatment.

We describe the unique case of a 73-year-old man who developed diffuse metastatic melanoma throughout the GI tract following potent immunosuppressive treatment for his immune-mediated colitis. Diagnosis of his metastatic GI luminal disease was confirmed with colonoscopy and EGD biopsies. Immunosuppressive therapy including corticosteroids and vedolizumab is the mainstay treatment for immune-mediated colitis and has generally been thought to have a safe toxicity profile. This unique case of diffuse luminal metastasis of melanoma after intensive immunosuppressant treatment raised the concern of their long-term safety on the cancer outcome and the need for safer alternatives.