Immune-related colitis presenting with constipation

Anticancer immunotherapies modulate the body’s immune system to recognise and eradicate cancerous cells. However, stimulation of the body’s immune system can also lead to a number of adverse effects when those immune cells target non-cancerous cells in the form of autoimmunity. One relatively common example of this off-target action is colitis. We present three patients who presented atypically with colitis, consequently, leading to a delayed diagnosis. These cases highlight the diverse ways a relatively common immune-related adverse event can present.