Delayed-Onset Isolated ICI (pembrolizumab)-Associated Gastritis with Concomitant Intussusception.

Immune checkpoint inhibitors are increasingly used in the treatment of a number of malignancies and carry a known risk of immune-related adverse events (irAEs). IrAEs cover a broad range of affected organ systems and presenting symptoms. While the gastrointestinal system is a commonly affected system, isolated gastritis is an uncommon diagnosis. We present a patient with isolated ICI-related gastritis presenting with concomitant intussusception caused by the anti-programmed cell death-1 antibody, pembrolizumab.