Development of Crohn's disease following anti-tumour necrosis factor therapy (etanercept).

Inhibition of tumour necrosis factor (TNF)-alpha is effective in the treatment of rheumatoid arthritis and other inflammatory rheumatic diseases. Anti-TNF antibodies such as infliximab, etanercept and adalimumab are commonly used. There are structural and functional differences among these agents. We describe development of Crohn's disease in a patient with ankylosing spondylitis receiving anti-TNF therapy. This case suggests that the appearance of gastrointestinal symptoms in patients on anti-TNF therapy must be evaluated to find out whether this is a new onset or an exacerbation of underlying inflammatory bowel disease.