Premalignant conditions of the small intestine.

Cancer of the small intestine is rare compared with other sites in the gastrointestinal tract. Of the four major primary small-bowel tumors (adenocarcinomas, lymphomas, carcinoid, and leiomyosarcomas), adenocarcinomas and lymphomas are associated with diseases that seem to increase the risk of developing these malignancies. In the case of immunoproliferative small intestinal disease and celiac disease, both of which are thought to predispose patients to the development of primary lymphoma, treatment of the predisposing conditions seems to decrease the risk of developing subsequent malignancy. Recognition of the increased risk associated with other conditions, such as immunodeficiency syndromes, nodular lymphoid hyperplasia, Crohn's disease, the gastrointestinal polyposis syndromes, hereditary nonpolyposis colon cancer, neurofibromatosis, long-standing ileostomy, and urinary diversion procedures, may lead to early diagnosis and improved survival.