Updates on the diagnosis and management of cryptogenic multifocal ulcerative stenosing enteropathy (CMUSE) and non-steroidal enteropathy

Crohn's disease and coeliac disease are well-known to induce ulcerations in the small-bowel. However, there is a group of very rare chronic ulcerative conditions of the small intestine that has emerged from the intestinal black box nearly 70 years ago, and that has gained interest with the advent of small-bowel capsule endoscopy and device-assisted enteroscopy. These distinct ulcerative enteropathies have come to our attention, and continue to reveal their aetiology and treatment options. Two distinct entities, called cryptogenic multifocal ulcerative stenosing enteritis/enteropathy (CMUSE) and chronic nonspecific multiple ulcers of the small intestine (CNSU) are gaining more clinical attention. CMUSE was first reported in Europe, whereas CNSU was exclusively diagnosed in Japanese patients. With the identification of susceptibility genes impacting prostaglandin metabolism, CMUSE and CNSU have become two distinct pathologies within the group of prostaglandin-associated enteropathies, to be differentiated from medication-induced enteropathies, especially non-steroidal anti-inflammatory drugs (NSAID)-induced enteropathy with similar intestinal ulcerations due to interference with prostaglandin metabolism. The current review provides an historical overview of CMUSE and CNSU publications, in addition to the currently available diagnostic and treatment options, and how to differentiate these rare enteropathies from NSAID-induced enteropathy.