Concurrent Immune-related Enteritis and Cytomegalovirus Enteritis during Immune Checkpoint Inhibitor Therapy.

Immune checkpoint inhibitors (ICIs) are widely used for advanced lung cancer; however, isolated ileitis and subsequent perforation are rare, particularly when complicated by cytomegalovirus (CMV) infection.A woman in her 50s with stage IV lung adenocarcinoma developed ICI-associated enteritis after atezolizumab-based therapy, which partially improved with corticosteroids and infliximab, but she later experienced ileal perforation following second-line chemotherapy. A histopathological examination revealed ICI-induced enteritis with cytomegalovirus (CMV) inclusions. Despite antiviral therapy with ganciclovir, the patient died. We present the first report of pathologically confirmed ICI-induced ileitis complicated by CMV enteritis in resected small bowel tissue.