Inflammatory pathology of the distal small bowel is relatively common. Three major clinical situations can be considered: a normal-appearing ileum on endoscopy, isolated ileitis, and ileocolitis. Acute enteritis is usually infectious in origin. Histology is not the best method for the diagnosis of enteric infections, because most acute enteritides are non-specific histologically and stool cultures or stool examination has a higher diagnostic yield. Chronic enteritis is less common and most notably caused by chronic infections such as yersiniosis and tuberculosis, by drugs and, in the Western world, primarily by Crohn’s disease. Inflammation called “backwash ileitis” can be present in the terminal ileum in patients with UC. Terminal ileum endoscopy and biopsy are considered as the gold standard for the differential diagnosis of chronic enteritis. The presence of endoscopic lesions and/or a clinical presentation with inflammatory diarrhea are the major indications for a biopsy. As endoscopy is now more frequently performed, pathologists are more likely to receive small intestinal samples and have to know the different features and the possible differential diagnosis between these pathologies.
KeywordsIleitis Acute enteritis Chronic enteritis Isolated ileitis Ileocolitis Backwash ileitis Crohn ileitis Yersiniosis Tuberculosis
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