Drug-induced mucosal injury (DIMI) of the gastrointestinal (GI) tract can be a major clinical challenge because most agents can cause a variety of clinical, endoscopic and histological patterns of damage while a recognisable pattern of GI injury is rarely specific for a particular drug. Furthermore, DIMI may mimic a variety of other GI diseases and consequently lead to the implementation of inappropriate treatment. In the lower GI tract, drug injury may mimic various colitides, including Inflammatory Bowel Disease (IBD). Therefore, knowledge of the range of patterns that each agent can cause and familiarity with contemporary approaches to the assessment and management of DIMI are important [1, 2]. A multidisciplinary approach increases the likelihood of accurate diagnosis because clinical history, laboratory tests, imaging, endoscopy and histopathology can all contribute to patient assessment.
Immune checkpoint inhibitors (ICI) are a relatively new group of anti-cancer drugs that are often highly effective at controlling advanced malignancy. ICIs induce various side effects, including an enterocolitis that ranges from mild to very severe. Close clinical and pathological mimicry of IBD is one of the manifestations of ICI GI toxicity. Other histological patterns include acute colitis, microscopic colitis, apoptosis and mixed patterns, while the clinical differential diagnosis is very broad (e.g. infection, other drugs, immune-related adverse events, diverticulosis and radiation damage) [3–6].
A joint ECCO Topical Review involving H-ECCO, Y-ECCO and EduCom is currently exploring DIMI, with a focus on IBD-like patterns. The working groups include expert representatives of gastroenterology, pathology, oncology and epidemiology. The review looks at the approaches to distinguishing DIMI from other causes of colitis and highlights the benefits of the interactions between clinicians and pathologists. There is an emphasis on ICI-induced colitis, including an update on risk factors, pathogenesis, diagnosis, assessment of severity and scoring schemes.
Over several consensus meetings, the group will discuss, agree on and formulate several ECCO clinical practice positions (CPPs). We believe that the CPPs and their accompanying texts will build on existing knowledge and help clinicians and pathologists to recognise and to manage effectively the relatively common scenario of drug-induced IBD-like enterocolitis.
