Tumorous Lesions of the Small Bowel

Abstract

Small bowel tumors are relatively rare. They can be classified as epithelial, mesenchymal, lymphoproliferative, or metastatic tumors. Endoscopic differential diagnosis usually starts with observation of the overlying epithelial layer. Neuroendocrine tumors, stromal tumors, hamartomas, lipomas, lymphangiomas, and inflammatory fibroid polyps are usually covered with normal epithelial layers. Stromal tumors, neuroendocrine tumors, and inflammatory fibroid polyps are usually firm, while most hamartomas, lipomas, and lymphangiomas are relatively soft. Yellowish adipose tissue in lipomas and clear fluid in lymphangiomas can be seen though the overlying mucosa. Stromal tumors and neuroendocrine tumors often present with surface ulcers. Unlike the above subepithelial lesions, the surface epithelium of adenoma and adenocarcinoma can be well discriminated from the surrounding normal mucosa. The epithelial layer of lymphomas and metastatic tumors also changes when tumor cells infiltrate the mucosal layer. Malignant lymphoma and gastrointestinal stromal tumors are thought to be the most common tumors in the small bowel.