Advanced precancerous lesions in the small bowel mucosa

The small intestine has comparatively low rates of epithelial cancers and is, for the most part, inaccessible to ordinary endoscopic visualization. As a result, few solid data are available on the pathological, clinical, and therapeutic aspects of epithelial dysplasia in the small intestine. In this review, we discuss the duodenal adenoma, the most readily visualized dysplastic lesion of the small intestine and the only one that can be detected in an early phase and resected endoscopically before it progresses to high-grade or invasive carcinoma. Particular emphasis is placed on the relationship between duodenal adenoma and colon neoplasia. Because of their different behaviour, detection and management of ampullary adenomas is discussed separately. Even if the absolute risk remains small, the incidence of adenocarcinoma in the small bowel is increased 32-fold in patients with ileal Crohn's disease. Therefore, the follow up and management of these patients is discussed with particular emphasis on the occurrence of dysplasia in the small bowel mucosa of the post-restorative proctocolectomy patients.