| [ Summary ] |
The incidence of neoplasms in the small intestine accounts for less than 5 % of all gastrointestinal neoplasms. Various kinds of tumors are identified in the small intestine and two thirds are found to be malignant. The comparatively frequent types of benign lesions observed are leiomyomas, lipomas, vascular tumors, neurogenic tumors, adenomas and lymphangiomas. Most (90 %) of malignant lesions are categorized as adenocarcinomas, carcinoid tumors, malignant lymphomas, or GISTs（gastrointestinal stromal tumors） . The prognosis for malignancy in the small intestine is poor because of the advanced stage at which they are often initially observed. It is expected that in the future prognoses related to malignant diseases in the small intestine will be improved through early diagnosis, thanks to recent progress in procedures for detecting disease in the small intestine. |